Without exaggeration, the international experimental thermonuclear reactor ITER can be called the most significant research project of our time. In terms of the scale of construction, it will easily outshine the Large Hadron Collider, and if successful, it will mark a much bigger step for all of humanity than a flight to the Moon. Indeed, potentially controlled thermonuclear fusion is an almost inexhaustible source of unprecedentedly cheap and clean energy.
This summer there were several good reasons to brush up on the technical details of the ITER project. Firstly, a grandiose undertaking, the official start of which is considered to be the meeting between Mikhail Gorbachev and Ronald Reagan back in 1985, is taking on material embodiment before our eyes. Designing a new generation reactor with the participation of Russia, the USA, Japan, China, India, South Korea and the European Union took more than 20 years. Today ITER is no longer kilograms technical documentation, and 42 hectares (1 km by 420 m) of a perfectly flat surface of one of the world's largest man-made platforms, located in the French city of Cadarache, 60 km north of Marseille. As well as the foundation of the future 360,000-ton reactor, consisting of 150,000 cubic meters of concrete, 16,000 tons of reinforcement and 493 columns with rubber-metal anti-seismic coating. And, of course, thousands of sophisticated scientific instruments and research facilities scattered across universities around the world.
March 2007. First photo of the future ITER platform from the air.
Production of key reactor components is well underway. In the spring, France reported the production of 70 frames for D-shaped toroidal field coils, and in June, winding of the first coils of superconducting cables, received from Russia from the Institute of Cable Industry in Podolsk, began.
The second good reason to remember ITER right now is political. The new generation reactor is a test not only for scientists, but also for diplomats. This is such an expensive and technically complex project that no country in the world can undertake it alone. The ability of states to reach agreement among themselves both in the scientific and financial spheres determines whether the matter will be completed.
March 2009. 42 hectares of leveled site are awaiting the start of construction of a scientific complex.
The ITER Council was scheduled for June 18 in St. Petersburg, but the US State Department, as part of sanctions, banned American scientists from visiting Russia. Taking into account the fact that the very idea of a tokamak (a toroidal chamber with magnetic coils, which is the basis of ITER) belongs to the Soviet physicist Oleg Lavrentiev, the project participants treated this decision as a curiosity and simply moved the meeting to Cadarache on the same date. These events once again reminded the whole world that Russia (along with South Korea) is most responsible for fulfilling its obligations to the ITER project.
February 2011. More than 500 holes were drilled in the seismic isolation shaft, all underground cavities were filled with concrete.
Scientists burn
The phrase “fusion reactor” makes many people wary. The associative chain is clear: a thermonuclear bomb is more terrible than just a nuclear one, which means that a thermonuclear reactor is more dangerous than Chernobyl.
In fact, nuclear fusion, on which the operating principle of the tokamak is based, is much safer and more efficient than nuclear fission used in modern nuclear power plants. Fusion is used by nature itself: the Sun is nothing more than a natural thermonuclear reactor.
The ASDEX tokamak, built in 1991 at Germany's Max Planck Institute, is used to test various reactor front wall materials, particularly tungsten and beryllium. The plasma volume in ASDEX is 13 m 3, almost 65 times less than in ITER.
The reaction involves nuclei of deuterium and tritium - isotopes of hydrogen. The deuterium nucleus consists of a proton and a neutron, and the tritium nucleus consists of a proton and two neutrons. Under normal conditions, equally charged nuclei repel each other, but at very high temperatures they can collide.
Upon collision, the strong interaction comes into play, which is responsible for combining protons and neutrons into nuclei. The nucleus of a new chemical element—helium—emerges. In this case, one free neutron is formed and a large amount of energy is released. The strong interaction energy in the helium nucleus is less than in the nuclei of the parent elements. Due to this, the resulting nucleus even loses mass (according to the theory of relativity, energy and mass are equivalent). Recalling the famous equation E = mc 2, where c is the speed of light, one can imagine the colossal energy potential nuclear fusion contains.
August 2011. The pouring of a monolithic reinforced concrete seismic isolating slab began.
To overcome the force of mutual repulsion, the initial nuclei must move very quickly, so temperature plays a key role in nuclear fusion. At the center of the Sun, the process occurs at a temperature of 15 million degrees Celsius, but it is facilitated by the colossal density of matter due to the action of gravity. The colossal mass of the star makes it an effective thermonuclear reactor.
It is not possible to create such a density on Earth. All we can do is increase the temperature. For hydrogen isotopes to release the energy of their nuclei to earthlings, a temperature of 150 million degrees is required, that is, ten times higher than on the Sun.
No solid material in the Universe can come into direct contact with such a temperature. So just building a stove to cook helium won’t work. The same toroidal chamber with magnetic coils, or tokamak, helps solve the problem. The idea of creating a tokamak dawned on the bright minds of scientists from different countries in the early 1950s, while the primacy is clearly attributed to the Soviet physicist Oleg Lavrentyev and his eminent colleagues Andrei Sakharov and Igor Tamm.
A vacuum chamber in the shape of a torus (a hollow donut) is surrounded by superconducting electromagnets, which create a toroidal magnetic field in it. It is this field that holds the plasma, hot up to ten times the sun, at a certain distance from the walls of the chamber. Together with the central electromagnet (inductor), the tokamak is a transformer. By changing the current in the inductor, they generate a current flow in the plasma - the movement of particles necessary for synthesis.
February 2012. 493 1.7-meter columns with seismic isolating pads made of rubber-metal sandwich were installed.
The Tokamak can rightfully be considered a model of technological elegance. The electric current flowing in the plasma creates a poloidal magnetic field that encircles the plasma cord and maintains its shape. Plasma exists under strictly defined conditions, and at the slightest change, the reaction immediately stops. Unlike a nuclear power plant reactor, a tokamak cannot “go wild” and increase the temperature uncontrollably.
In the unlikely event of destruction of the tokamak, there is no radioactive contamination. Unlike a nuclear power plant, a thermonuclear reactor does not produce radioactive waste, and the only product of the fusion reaction - helium - is not a greenhouse gas and is useful in the economy. Finally, the tokamak uses fuel very sparingly: during synthesis, only a few hundred grams of substance are contained in the vacuum chamber, and the estimated annual supply of fuel for an industrial power plant is only 250 kg.
April 2014. Construction of the cryostat building was completed, the walls of the 1.5-meter thick tokamak foundation were poured.
Why do we need ITER?
Tokamaks of the classical design described above were built in the USA and Europe, Russia and Kazakhstan, Japan and China. With their help, it was possible to prove the fundamental possibility of creating high-temperature plasma. However, building an industrial reactor capable of delivering more energy than it consumes is a task of a fundamentally different scale.
In a classic tokamak, the current flow in the plasma is created by changing the current in the inductor, and this process cannot be endless. Thus, the lifetime of the plasma is limited, and the reactor can only operate in pulsed mode. Ignition of plasma requires colossal energy - it’s no joke to heat anything to a temperature of 150,000,000 °C. This means that it is necessary to achieve a plasma lifetime that will produce energy that pays for ignition.
The fusion reactor is an elegant technical concept with minimal negative side effects. The flow of current in the plasma spontaneously forms a poloidal magnetic field that maintains the shape of the plasma filament, and the resulting high-energy neutrons combine with lithium to produce precious tritium.
For example, in 2009, during an experiment on the Chinese tokamak EAST (part of the ITER project), it was possible to maintain plasma at a temperature of 10 7 K for 400 seconds and 10 8 K for 60 seconds.
To hold the plasma longer, additional heaters of several types are needed. All of them will be tested at ITER. The first method - injection of neutral deuterium atoms - assumes that the atoms will enter the plasma pre-accelerated to kinetic energy at 1 MeV using an additional accelerator.
This process is initially contradictory: only charged particles can be accelerated (they are affected by an electromagnetic field), and only neutral ones can be introduced into the plasma (otherwise they will affect the flow of current inside the plasma cord). Therefore, an electron is first removed from deuterium atoms, and positively charged ions enter the accelerator. The particles then enter the neutralizer, where they are reduced to neutral atoms by interacting with the ionized gas and introduced into the plasma. The ITER megavoltage injector is currently being developed in Padua, Italy.
The second heating method has something in common with heating food in the microwave. It involves exposing the plasma to electromagnetic radiation with a frequency corresponding to the speed of particle movement (cyclotron frequency). For positive ions this frequency is 40−50 MHz, and for electrons it is 170 GHz. To create powerful radiation of such a high frequency, a device called a gyrotron is used. Nine of the 24 ITER gyrotrons are manufactured at the Gycom facility in Nizhny Novgorod.
The classical concept of a tokamak assumes that the shape of the plasma filament is supported by a poloidal magnetic field, which is itself formed when current flows in the plasma. This approach is not applicable for long-term plasma confinement. The ITER tokamak has special poloidal field coils, the purpose of which is to keep the hot plasma away from the walls of the reactor. These coils are among the most massive and complex structural elements.
In order to be able to actively control the shape of the plasma, promptly eliminating vibrations at the edges of the cord, the developers provided small, low-power electromagnetic circuits located directly in the vacuum chamber, under the casing.
Fuel infrastructure for thermonuclear fusion is a separate interesting topic. Deuterium is found in almost any water, and its reserves can be considered unlimited. But the world's reserves of tritium amount to tens of kilograms. 1 kg of tritium costs about $30 million. For the first launches of ITER, 3 kg of tritium will be needed. By comparison, about 2 kg of tritium per year is needed to maintain the nuclear capabilities of the United States Army.
However, in the future, the reactor will provide itself with tritium. The main fusion reaction produces high-energy neutrons that are capable of converting lithium nuclei into tritium. The development and testing of the first lithium reactor wall is one of ITER's most important goals. The first tests will use beryllium-copper cladding, the purpose of which is to protect the reactor mechanisms from heat. According to calculations, even if we transfer the entire energy sector of the planet to tokamaks, the world's lithium reserves will be enough for a thousand years of operation.
Preparing the 104-kilometer ITER Path cost France 110 million euros and four years of work. The road from the port of Fos-sur-Mer to Cadarache was widened and strengthened so that the heaviest and largest parts of the tokamak could be delivered to the site. In the photo: a transporter with a test load weighing 800 tons.
From the world via tokamak
Precision control of a fusion reactor requires precise diagnostic tools. One of the key tasks of ITER is to select the most suitable of the five dozen instruments that are currently being tested, and to begin the development of new ones.
At least nine diagnostic devices will be developed in Russia. Three are at the Moscow Kurchatov Institute, including a neutron beam analyzer. The accelerator sends a focused stream of neutrons through the plasma, which undergoes spectral changes and is captured by the receiving system. Spectrometry with a frequency of 250 measurements per second shows the temperature and density of the plasma, the strength of the electric field and the speed of particle rotation - parameters necessary to control the reactor for long-term plasma containment.
The Ioffe Research Institute is preparing three instruments, including a neutral particle analyzer that captures atoms from the tokamak and helps monitor the concentration of deuterium and tritium in the reactor. The remaining devices will be made at Trinity, where diamond detectors for the ITER vertical neutron chamber are currently being manufactured. All of the above institutes use their own tokamaks for testing. And in the thermal chamber of the Efremov NIIEFA, fragments of the first wall and the diverter target of the future ITER reactor are being tested.
Unfortunately, the fact that many of the components of a future mega-reactor already exist in the metal does not necessarily mean that the reactor will be built. Over the past decade, the estimated cost of the project has grown from 5 to 16 billion euros, and the planned first launch has been postponed from 2010 to 2020. The fate of ITER depends entirely on the realities of our present, primarily economic and political. Meanwhile, every scientist involved in the project sincerely believes that its success can change our future beyond recognition.
Fusion power plant.
Currently, scientists are working on the creation of a thermonuclear power plant, the advantage of which is to provide humanity with electricity for an unlimited time. A thermonuclear power plant operates on the basis of thermonuclear fusion - the reaction of synthesis of heavy hydrogen isotopes with the formation of helium and the release of energy. The thermonuclear fusion reaction does not produce gaseous or liquid radioactive waste and does not produce plutonium, which is used to produce nuclear weapons. If we also take into account that the fuel for thermonuclear stations will be the heavy hydrogen isotope deuterium, which is obtained from simple water - half a liter of water contains fusion energy equivalent to that obtained by burning a barrel of gasoline - then the advantages of power plants based on thermonuclear reactions become obvious .
During a thermonuclear reaction, energy is released when light atoms combine and transform into heavier ones. To achieve this, it is necessary to heat the gas to a temperature of over 100 million degrees - much higher than the temperature at the center of the Sun.
Gas at this temperature turns into plasma. At the same time, atoms of hydrogen isotopes merge, turning into helium atoms and neutrons and releasing a large amount of energy. A commercial power plant operating on this principle would use the energy of neutrons moderated by a layer of dense material (lithium).
Compared to a nuclear power plant, a fusion reactor will leave behind much less radioactive waste.
International thermonuclear reactor ITER
Participants in the international consortium to create the world's first thermonuclear reactor, ITER, signed an agreement in Brussels, giving the start practical implementation project.
Representatives of the European Union, the United States, Japan, China, South Korea and Russia intend to begin construction of the experimental reactor in 2007 and complete it within eight years. If everything goes according to plan, then by 2040 a demonstration power plant operating on the new principle could be built.
I would like to believe that the era of environmentally hazardous hydroelectric and nuclear power plants will soon end, and the time will come for a new power plant - a thermonuclear one, the project of which is already being implemented. But, despite the fact that the ITER (International Thermonuclear Reactor) project is almost ready; Despite the fact that already at the first operating experimental thermonuclear reactors a power exceeding 10 MW was obtained - the level of the first nuclear power plants, the first thermonuclear power plant will not start working earlier than in twenty years, because its cost is very high. The cost of the work is estimated at 10 billion euros - this is the most expensive international power plant project. Half of the costs of constructing the reactor are covered by the European Union. Other consortium participants will allocate 10% of the estimate.
Now the plan for the construction of the reactor, which will become the most expensive joint scientific project ever, must be ratified by parliamentarians of the consortium member countries.
The reactor will be built in the southern French province Provence, in the vicinity of the city of Cadarache, where the French nuclear research center is located.
The second half of the 20th century was a period of rapid development of nuclear physics. It became clear that nuclear reactions could be used to produce enormous energy from tiny amounts of fuel. From the explosion of the first nuclear bomb Only nine years passed before the first nuclear power plant, and when the hydrogen bomb was tested in 1952, there were predictions that thermonuclear power plants would come into operation in the 1960s. Alas, these hopes were not justified.
Thermonuclear reactions Of all the thermonuclear reactions, only four are of interest in the near future: deuterium + deuterium (products - tritium and proton, released energy 4.0 MeV), deuterium + deuterium (helium-3 and neutron, 3.3 MeV), deuterium + tritium (helium-4 and neutron, 17.6 MeV) and deuterium + helium-3 (helium-4 and proton, 18.2 MeV). The first and second reactions occur in parallel with equal probability. The resulting tritium and helium-3 “burn” in the third and fourth reactions
The main source of energy for humanity today is the combustion of coal, oil and gas. But their supplies are limited, and combustion products pollute the environment. A coal power plant produces more radioactive emissions than a nuclear power plant of the same power! So why haven't we switched to nuclear energy sources yet? There are many reasons for this, but the main one is Lately became radiophobia. Despite the fact that a coal-fired power plant, even during normal operation, harms the health of many more people than emergency emissions at a nuclear power plant, it does so quietly and unnoticed by the public. Accidents at nuclear power plants immediately become the main news in the media, causing general panic (often completely unfounded). However, this does not mean that nuclear energy does not have objective problems. Radioactive waste causes a lot of trouble: technologies for working with it are still extremely expensive, and the ideal situation when all of it will be completely recycled and used is still far away.
Of all the thermonuclear reactions, only four are of interest in the near future: deuterium + deuterium (products - tritium and proton, released energy 4.0 MeV), deuterium + deuterium (helium-3 and neutron, 3.3 MeV), deuterium + tritium (helium -4 and neutron, 17.6 MeV) and deuterium + helium-3 (helium-4 and proton, 18.2 MeV). The first and second reactions occur in parallel with equal probability. The resulting tritium and helium-3 “burn” in the third and fourth reactions.
From fission to fusion
A potential solution to these problems is the transition from fission reactors to fusion reactors. While a typical fission reactor contains tens of tons of radioactive fuel, which is converted into tens of tons of radioactive waste containing a wide variety of radioactive isotopes, a fusion reactor uses only hundreds of grams, maximum kilograms, of one radioactive isotope of hydrogen, tritium. In addition to the fact that the reaction requires an insignificant amount of this least dangerous radioactive isotope, its production is also planned to be carried out directly at the power plant in order to minimize the risks associated with transportation. The synthesis products are stable (non-radioactive) and non-toxic hydrogen and helium. In addition, unlike a fission reaction, a thermonuclear reaction immediately stops when the installation is destroyed, without creating the danger of a thermal explosion. So why has not a single operational thermonuclear power plant been built yet? The reason is that the listed advantages inevitably entail disadvantages: creating the conditions for synthesis turned out to be much more difficult than initially expected.
Lawson criterion
For a thermonuclear reaction to be energetically favorable, it is necessary to ensure a sufficiently high temperature of the thermonuclear fuel, a sufficiently high density and sufficiently low energy losses. The latter are numerically characterized by the so-called “retention time”, which is equal to the ratio of the thermal energy stored in the plasma to the energy loss power (many people mistakenly believe that the “retention time” is the time during which hot plasma is maintained in the installation, but this is not so) . At a temperature of a mixture of deuterium and tritium equal to 10 keV (approximately 110,000,000 degrees), we need to obtain the product of the number of fuel particles in 1 cm 3 (i.e., plasma concentration) and the retention time (in seconds) of at least 10 14. It does not matter whether we have a plasma with a concentration of 1014 cm -3 and a retention time of 1 s, or a plasma with a concentration of 10 23 and a retention time of 1 ns. This criterion is called the Lawson criterion.
In addition to the Lawson criterion, which is responsible for obtaining an energetically favorable reaction, there is also a plasma ignition criterion, which for the deuterium-tritium reaction is approximately three times greater than the Lawson criterion. “Ignition” means that the fraction of thermonuclear energy that remains in the plasma will be enough to maintain required temperature, and additional heating of the plasma will no longer be required.
Z-pinch
The first device in which it was planned to obtain a controlled thermonuclear reaction was the so-called Z-pinch. In the simplest case, this installation consists of only two electrodes located in a deuterium (hydrogen-2) environment or a mixture of deuterium and tritium, and a battery of high-voltage pulse capacitors. At first glance, it seems that it makes it possible to obtain compressed plasma heated to enormous temperatures: exactly what is needed for a thermonuclear reaction! However, in life, everything turned out, alas, to be far from so rosy. The plasma rope turned out to be unstable: the slightest bend leads to a strengthening of the magnetic field on one side and a weakening on the other; the resulting forces further increase the bending of the rope - and all the plasma “falls out” onto the side wall of the chamber. The rope is not only unstable to bending, the slightest thinning of it leads to an increase in the magnetic field in this part, which compresses the plasma even more, squeezing it into the remaining volume of the rope until the rope is finally “squeezed out.” The compressed part has a high electrical resistance, so the current is interrupted, the magnetic field disappears, and all the plasma dissipates.
The principle of operation of the Z-pinch is simple: an electric current generates an annular magnetic field, which interacts with the same current and compresses it. As a result, the density and temperature of the plasma through which the current flows increases.
It was possible to stabilize the plasma bundle by applying a powerful external magnetic field to it, parallel to the current, and placing it in a thick conductive casing (as the plasma moves, the magnetic field also moves, which induces an electric current in the casing, tending to return the plasma to its place). The plasma stopped bending and pinching, but it was still far from a thermonuclear reaction on any serious scale: the plasma touches the electrodes and gives off its heat to them.
Modern work in the field of Z-pinch fusion suggests another principle for creating fusion plasma: a current flows through a tungsten plasma tube, which creates powerful X-rays that compress and heat the capsule with fusion fuel located inside the plasma tube, just as it does in a thermonuclear bomb. However, these works are purely research in nature (the mechanisms of operation of nuclear weapons are studied), and the energy release in this process is still millions of times less than consumption.
The smaller the ratio of the large radius of the tokamak torus (the distance from the center of the entire torus to the center of the cross-section of its pipe) to the small one (the cross-section radius of the pipe), the greater the plasma pressure can be under the same magnetic field. By reducing this ratio, scientists moved from a circular cross-section of the plasma and vacuum chamber to a D-shaped one (in this case, the role of the small radius is played by half the height of the cross-section). All modern tokamaks have exactly this cross-sectional shape. The limiting case was the so-called “spherical tokamak”. In such tokamaks, the vacuum chamber and plasma are almost spherical in shape, with the exception of a narrow channel connecting the poles of the sphere. The conductors of magnetic coils pass through the channel. The first spherical tokamak, START, appeared only in 1991, so this is a fairly young direction, but it has already shown the possibility of obtaining the same plasma pressure with a three times lower magnetic field.
Cork chamber, stellarator, tokamak
Another option for creating the conditions necessary for the reaction is the so-called open magnetic traps. The most famous of them is the “cork cell”: a pipe with a longitudinal magnetic field that strengthens at its ends and weakens in the middle. The field increased at the ends creates a “magnetic plug” (hence the Russian name), or “magnetic mirror” (English - mirror machine), which keeps the plasma from leaving the installation through the ends. However, such retention is incomplete; some charged particles moving along certain trajectories are able to pass through these jams. And as a result of collisions, any particle will sooner or later fall on such a trajectory. In addition, the plasma in the mirror cell also turned out to be unstable: if in some place small area As the plasma moves away from the installation axis, forces arise that eject the plasma onto the chamber wall. Although the basic idea of the mirror cell was significantly improved (which made it possible to reduce both the instability of the plasma and the permeability of the mirrors), in practice it was not even possible to approach the parameters necessary for energetically favorable synthesis.
Is it possible to make sure that the plasma does not escape through the “plugs”? It would seem that the obvious solution is to roll the plasma into a ring. However, then the magnetic field inside the ring is stronger than outside, and the plasma again tends to go to the chamber wall. Way out of this difficult situation also seemed quite obvious: instead of a ring, make a “figure eight”, then in one section the particle will move away from the axis of the installation, and in another it will return back. This is how scientists came up with the idea of the first stellarator. But such a “figure of eight” cannot be made in one plane, so we had to use the third dimension, bending the magnetic field in the second direction, which also led to a gradual movement of the particles from the axis to the chamber wall.
The situation changed dramatically with the creation of tokamak-type installations. The results obtained at the T-3 tokamak in the second half of the 1960s were so stunning for that time that Western scientists came to the USSR with their measuring equipment to verify the plasma parameters themselves. The reality even exceeded their expectations.
These fantastically intertwined tubes are not an art project, but a stellarator chamber bent into a complex three-dimensional curve.
In the hands of inertia
In addition to magnetic confinement, there is a fundamentally different approach to thermonuclear fusion - inertial confinement. If in the first case we try to keep the plasma at a very low concentration for a long time (the concentration of molecules in the air around you is hundreds of thousands of times higher), then in the second case we compress the plasma to a huge density, an order of magnitude higher than the density of the most heavy metals, in the expectation that the reaction will have time to complete a short time, before the plasma had time to scatter to the sides.
Originally, in the 1960s, the plan was to use a small ball of frozen fusion fuel, uniformly irradiated from all sides by multiple laser beams. The surface of the ball should have instantly evaporated and, expanding evenly in all directions, compressed and heated the remaining part of the fuel. However, in practice, the irradiation turned out to be insufficiently uniform. In addition, part of the radiation energy was transferred to the inner layers, causing them to heat up, which made compression more difficult. As a result, the ball compressed unevenly and weakly.
There are a number of modern stellarator configurations, all of which are close to a torus. One of the most common configurations involves the use of coils similar to the poloidal field coils of tokamaks, and four to six conductors twisted around a vacuum chamber with multidirectional current. The complex magnetic field created in this way allows the plasma to be reliably contained without requiring a ring electric current to flow through it. In addition, stellarators can also use toroidal field coils, like tokamaks. And there may be no helical conductors, but then the “toroidal” field coils are installed along a complex three-dimensional curve. Recent developments in the field of stellarators involve the use of magnetic coils and a vacuum chamber of a very complex shape (a very “crumpled” torus), calculated on a computer.
The problem of unevenness was solved by significantly changing the design of the target. Now the ball is placed inside a special small metal chamber (it is called “holraum”, from the German hohlraum - cavity) with holes through which laser beams enter inside. In addition, crystals are used that convert IR laser radiation into ultraviolet. This UV radiation is absorbed the thinnest layer hohlraum material, which is heated to enormous temperatures and emits in the soft x-ray region. In turn, X-ray radiation is absorbed by a thin layer on the surface of the fuel capsule (ball with fuel). This also made it possible to solve the problem of premature heating of the internal layers.
However, the power of the lasers turned out to be insufficient for a noticeable portion of the fuel to react. In addition, the efficiency of the lasers was very low, only about 1%. For fusion to be energetically beneficial at such a low laser efficiency, almost all of the compressed fuel had to react. When trying to replace lasers with beams of light or heavy ions, which can be generated with much greater efficiency, scientists also encountered a lot of problems: light ions repel each other, which prevents them from focusing, and are slowed down when colliding with residual gas in the chamber, and accelerators It was not possible to create heavy ions with the required parameters.
Magnetic prospects
Most of the hope in the field of fusion energy now lies in tokamaks. Especially after they opened a mode with improved retention. A tokamak is both a Z-pinch rolled into a ring (a ring electric current flows through the plasma, creating a magnetic field necessary to contain it), and a sequence of mirror cells assembled into a ring and creating a “corrugated” toroidal magnetic field. In addition, a field perpendicular to the torus plane, created by several individual coils, is superimposed on the toroidal field of the coils and the plasma current field. This additional field, called poloidal, strengthens the magnetic field of the plasma current (also poloidal) from the outside of the torus and weakens it from inside. Thus, the total magnetic field on all sides of the plasma rope turns out to be the same, and its position remains stable. By changing this additional field, it is possible to move the plasma bundle inside the vacuum chamber within certain limits.
A fundamentally different approach to synthesis is proposed by the concept of muon catalysis. A muon is an unstable elementary particle that has the same charge as an electron, but 207 times more mass. A muon can replace an electron in a hydrogen atom, and the size of the atom decreases by a factor of 207. This allows one hydrogen nucleus to move closer to another without expending energy. But to produce one muon, about 10 GeV of energy is spent, which means it is necessary to perform several thousand fusion reactions per muon to obtain energy benefits. Due to the possibility of a muon “sticking” to the helium formed in the reaction, more than several hundred reactions have not yet been achieved. The photo shows the assembly of the Wendelstein z-x stellarator at the Max Planck Institute for Plasma Physics.
An important problem of tokamaks for a long time was the need to create a ring current in the plasma. To do this, a magnetic circuit was passed through the central hole of the tokamak torus, the magnetic flux in which was continuously changed. The change in magnetic flux generates a vortex electric field, which ionizes the gas in the vacuum chamber and maintains current in the resulting plasma. However, the current in the plasma must be maintained continuously, which means that the magnetic flux must continuously change in one direction. This, of course, is impossible, so the current in tokamaks could only be maintained for a limited time (from a fraction of a second to several seconds). Fortunately, the so-called bootstrap current was discovered, which occurs in a plasma without an external vortex field. In addition, methods have been developed to heat the plasma, simultaneously inducing the necessary ring current in it. Together, this provided the potential for maintaining hot plasma for as long as desired. In practice, the record currently belongs to the Tore Supra tokamak, where the plasma continuously “burned” for more than six minutes.
The second type of plasma confinement installation, which has great promise, is stellarators. Over the past decades, the design of stellarators has changed dramatically. Almost nothing remained of the original “eight”, and these installations became much closer to tokamaks. Although the confinement time of stellarators is shorter than that of tokamaks (due to the less efficient H-mode), and the cost of their construction is higher, the behavior of the plasma in them is calmer, which means a longer life of the first inner wall of the vacuum chamber. For the commercial development of thermonuclear fusion, this factor is of great importance.
Selecting a reaction
At first glance, it is most logical to use pure deuterium as a thermonuclear fuel: it is relatively cheap and safe. However, deuterium reacts with deuterium a hundred times less readily than with tritium. This means that to operate a reactor on a mixture of deuterium and tritium, a temperature of 10 keV is sufficient, and to operate on pure deuterium, a temperature of more than 50 keV is required. And the higher the temperature, the higher the energy loss. Therefore, at least for the first time, thermonuclear energy is planned to be built on deuterium-tritium fuel. Tritium will be produced in the reactor itself due to irradiation with the fast lithium neutrons produced in it.
"Wrong" neutrons. In the cult film "9 Days of One Year" main character, while working at a thermonuclear installation, received a serious dose of neutron radiation. However, it later turned out that these neutrons were not produced as a result of a fusion reaction. This is not the director’s invention, but a real effect observed in Z-pinches. At the moment of interruption of the electric current, the inductance of the plasma leads to the generation of a huge voltage - millions of volts. Individual hydrogen ions, accelerated in this field, are capable of literally knocking neutrons out of the electrodes. At first, this phenomenon was indeed taken as a sure sign of a thermonuclear reaction, but subsequent analysis of the neutron energy spectrum showed that they had a different origin.
Improved retention mode. The H-mode of a tokamak is a mode of its operation when, with a high power of additional heating, plasma energy losses sharply decrease. The accidental discovery of the enhanced confinement mode in 1982 is as significant as the invention of the tokamak itself. There is no generally accepted theory of this phenomenon yet, but this does not prevent it from being used in practice. All modern tokamaks operate in this mode, as it reduces losses by more than half. Subsequently, a similar regime was discovered in stellarators, indicating that this is a general property of toroidal systems, but confinement is only improved by about 30% in them.
Plasma heating. There are three main methods of heating plasma to thermonuclear temperatures. Ohmic heating is the heating of plasma due to the flow of electric current through it. This method is most effective in the first stages, since as the temperature increases, the electrical resistance of the plasma decreases. Electromagnetic heating uses electromagnetic waves with a frequency that matches the frequency of rotation around the magnetic field lines of electrons or ions. By injecting fast neutral atoms, a stream of negative ions is created, which are then neutralized, turning into neutral atoms that can pass through the magnetic field to the center of the plasma to transfer their energy there.
Are these reactors? Tritium is radioactive, and powerful neutron irradiation from the D-T reaction creates induced radioactivity in the reactor design elements. We have to use robots, which complicates the work. At the same time, the behavior of a plasma of ordinary hydrogen or deuterium is very close to the behavior of a plasma from a mixture of deuterium and tritium. This led to the fact that throughout history, only two thermonuclear installations fully operated on a mixture of deuterium and tritium: the TFTR and JET tokamaks. At other installations, even deuterium is not always used. So the name “thermonuclear” in the definition of a facility does not at all mean that thermonuclear reactions have ever actually occurred in it (and in those that do occur, pure deuterium is almost always used).
Hybrid reactor. The D-T reaction produces 14 MeV neutrons, which can even fission depleted uranium. The fission of one uranium nucleus is accompanied by the release of approximately 200 MeV of energy, which is more than ten times the energy released during fusion. So existing tokamaks could become energetically beneficial if they were surrounded by a uranium shell. Compared to fission reactors, such hybrid reactors would have the advantage of preventing an uncontrolled chain reaction from developing in them. In addition, extremely intense neutron fluxes should convert long-lived uranium fission products into short-lived ones, which significantly reduces the problem of waste disposal.
Inertial hopes
Inertial fusion is also not standing still. Over the decades of development of laser technology, prospects have emerged to increase the efficiency of lasers by approximately ten times. And in practice, their power has been increased hundreds and thousands of times. Work is also underway on heavy ion accelerators with parameters suitable for thermonuclear use. In addition, the concept of “fast ignition” has been a critical factor in the progress of inertial fusion. It involves the use of two pulses: one compresses the thermonuclear fuel, and the other heats up a small part of it. It is assumed that the reaction that begins in a small part of the fuel will subsequently spread further and cover the entire fuel. This approach makes it possible to significantly reduce energy costs, and therefore make the reaction profitable with a smaller fraction of reacted fuel.
Tokamak problems
Despite the progress of installations of other types, tokamaks at the moment still remain out of competition: if two tokamaks (TFTR and JET) back in the 1990s actually produced a release of thermonuclear energy approximately equal to the energy consumption for heating the plasma (even though such a mode lasted only about a second), then nothing similar could be achieved with other types of installations. Even a simple increase in the size of tokamaks will lead to the feasibility of energetically favorable fusion in them. Currently under construction in France international reactor ITER, which will have to demonstrate this in practice.
However, tokamaks also have problems. ITER costs billions of dollars, which is unacceptable for future commercial reactors. No reactor has operated continuously for even a few hours, let alone for weeks and months, which again is necessary for industrial applications. There is no certainty yet that the materials of the inner wall of the vacuum chamber will be able to withstand prolonged exposure to plasma.
The concept of a tokamak with a strong field can make the project less expensive. By increasing the field by two to three times, it is planned to obtain the required plasma parameters in a relatively small installation. This concept, in particular, is the basis for the Ignitor reactor, which, together with Italian colleagues, is now beginning to be built at TRINIT (Trinity Institute for Innovation and Thermonuclear Research) near Moscow. If the engineers’ calculations come true, then at a cost many times lower than ITER, it will be possible to ignite plasma in this reactor.
Forward to the stars!
The products of a thermonuclear reaction fly away in different directions at speeds of thousands of kilometers per second. This makes it possible to create ultra-efficient rocket engines. Their specific impulse will be higher than that of the best electric jet engines, and their energy consumption may even be negative (theoretically, it is possible to generate, rather than consume, energy). Moreover, there is every reason to believe that making a thermonuclear rocket engine will be even easier than a ground-based reactor: there is no problem with creating a vacuum, with thermal insulation of superconducting magnets, there are no restrictions on dimensions, etc. In addition, the generation of electricity by the engine is desirable, but It’s not at all necessary, it’s enough that he doesn’t consume too much of it.
Electrostatic confinement
The concept of electrostatic ion confinement is most easily understood through a setup called a fusor. It is based on a spherical mesh electrode, to which a negative potential is applied. Ions accelerated in a separate accelerator or by the field of the central electrode itself fall inside it and are held there by an electrostatic field: if an ion tends to fly out, the electrode field turns it back. Unfortunately, the probability of an ion colliding with a network is many orders of magnitude higher than the probability of entering into a fusion reaction, which makes an energetically favorable reaction impossible. Such installations have found application only as neutron sources.
In an effort to make a sensational discovery, many scientists strive to see synthesis wherever possible. There have been numerous reports in the press regarding various options so-called “cold fusion”. Synthesis was discovered in metals “impregnated” with deuterium when an electric current flows through them, during the electrolysis of deuterium-saturated liquids, during the formation of cavitation bubbles in them, as well as in other cases. However, most of these experiments have not had satisfactory reproducibility in other laboratories, and their results can almost always be explained without the use of synthesis.
Continuing the “glorious tradition” that began with the “philosopher’s stone” and then turned into a “perpetual motion machine”, many modern scammers are offering to buy from them a “cold fusion generator”, “cavitation reactor” and other “fuel-free generators”: about the philosophical Everyone has already forgotten the stone, they don’t believe in perpetual motion, but nuclear fusion now sounds quite convincing. But, alas, in reality such energy sources do not exist yet (and when they can be created, it will be in all news releases). So be aware: if you are offered to buy a device that generates energy through cold nuclear fusion, then they are simply trying to “cheat” you!
According to preliminary estimates, even with the current level of technology it is possible to create a thermonuclear rocket engine for a flight to the planets of the solar system (with appropriate funding). Mastering the technology of such engines will increase the speed of manned flights tenfold and will make it possible to have large reserve fuel reserves on board, which will make flying to Mars no more difficult than working on the ISS now. Speeds of 10% of the speed of light will potentially become available for automatic stations, which means it will be possible to send research probes to nearby stars and obtain scientific data during the lifetime of their creators.
The concept of a thermonuclear rocket engine based on inertial fusion is currently considered the most developed. The difference between an engine and a reactor lies in the magnetic field, which directs the charged reaction products in one direction. The second option involves using an open trap, in which one of the plugs is deliberately weakened. The plasma flowing from it will create a reactive force.
Thermonuclear future
Mastering thermonuclear fusion turned out to be many orders of magnitude more difficult than it seemed at first. And although many problems have already been solved, the remaining ones will be enough for the next few decades of hard work of thousands of scientists and engineers. But the prospects that the transformations of hydrogen and helium isotopes open up for us are so great, and the path taken is already so significant that it makes no sense to stop halfway. No matter what numerous skeptics say, the future undoubtedly lies in synthesis.
How did it all start? The “energy challenge” arose as a result of a combination of the following three factors:
1. Humanity now consumes a huge amount of energy.
Currently, the world's energy consumption is about 15.7 terawatts (TW). Dividing this value by the world population, we get approximately 2400 watts per person, which can be easily estimated and visualized. The energy consumed by every inhabitant of the Earth (including children) corresponds to the round-the-clock operation of 24 hundred-watt electric lamps. However, the consumption of this energy across the planet is very uneven, as it is very large in several countries and negligible in others. Consumption (in terms of one person) is equal to 10.3 kW in the USA (one of the record values), 6.3 kW in the Russian Federation, 5.1 kW in the UK, etc., but, on the other hand, it is equal only 0.21 kW in Bangladesh (only 2% of US energy consumption!).
2. World energy consumption is increasing dramatically.
According to the International Energy Agency (2006), global energy consumption is expected to increase by 50% by 2030. Developed countries could, of course, do just fine without additional energy, but this growth is necessary to lift people out of poverty in developing countries, where 1.5 billion people suffer from severe power shortages.
3. Currently, 80% of the world's energy comes from burning fossil fuels(oil, coal and gas), the use of which:
a) potentially poses a risk of catastrophic environmental changes;
b) inevitably must end someday.
From what has been said, it is clear that now we must prepare for the end of the era of using fossil fuels
Currently, nuclear power plants produce energy released during fission reactions of atomic nuclei on a large scale. The creation and development of such stations should be encouraged in every possible way, but it must be taken into account that the reserves of one of the most important materials for their operation (cheap uranium) can also be completely used up within the next 50 years. The possibilities of nuclear fission-based energy can (and should) be significantly expanded through the use of more efficient energy cycles, allowing the amount of energy produced to almost double. To develop energy in this direction, it is necessary to create thorium reactors (the so-called thorium breeder reactors or breeder reactors), in which the reaction produces more thorium than the original uranium, as a result of which the total amount of energy produced for a given amount of substance increases by 40 times . It also seems promising to create plutonium breeders using fast neutrons, which are much more efficient than uranium reactors and can produce 60 times more energy. It may be that to develop these areas it will be necessary to develop new, non-standard methods for obtaining uranium (for example, from sea water, which seems to be the most accessible).
Fusion power plants
The figure shows a schematic diagram (not to scale) of the device and operating principle of a thermonuclear power plant. In the central part there is a toroidal (donut-shaped) chamber with a volume of ~2000 m3, filled with tritium-deuterium (T–D) plasma heated to a temperature above 100 M°C. The neutrons produced during the fusion reaction (1) leave the “magnetic bottle” and enter the shell shown in the figure with a thickness of about 1 m.
Inside the shell, neutrons collide with lithium atoms, resulting in a reaction that produces tritium:
neutron + lithium → helium + tritium
In addition, competing reactions occur in the system (without the formation of tritium), as well as many reactions with the release of additional neutrons, which then also lead to the formation of tritium (in this case, the release of additional neutrons can be significantly enhanced, for example, by introducing beryllium atoms into the shell and lead). The general conclusion is that this facility could (at least theoretically) undergo a nuclear fusion reaction that would produce tritium. In this case, the amount of tritium produced should not only meet the needs of the installation itself, but also be even somewhat larger, which will make it possible to supply new installations with tritium. It is this operating concept that must be tested and implemented in the ITER reactor described below.
In addition, neutrons must heat the shell in so-called pilot plants (in which relatively “ordinary” construction materials will be used) to approximately 400°C. In the future, it is planned to create improved installations with a shell heating temperature above 1000°C, which can be achieved through the use of the latest high-strength materials (such as silicon carbide composites). The heat generated in the shell, as in conventional stations, is taken by the primary cooling circuit with a coolant (containing, for example, water or helium) and transferred to the secondary circuit, where water steam is produced and supplied to the turbines.
1985 - The Soviet Union proposed the next generation Tokamak plant, using the experience of four leading countries in creating fusion reactors. The United States of America, together with Japan and the European Community, put forward a proposal for the implementation of the project.
Currently, in France, construction is underway on the international experimental thermonuclear reactor ITER (International Tokamak Experimental Reactor), described below, which will be the first tokamak capable of “igniting” plasma.
In the most advanced existing installations The Tokamak type has long reached temperatures of the order of 150 M°C, close to the values required for the operation of a thermonuclear station, but the ITER reactor should become the first large-scale power plant designed for long-term operation. In the future, it will be necessary to significantly improve its operating parameters, which will require, first of all, increasing the pressure in the plasma, since the rate of nuclear fusion at a given temperature is proportional to the square of the pressure. The main scientific problem in this case is related to the fact that when the pressure in the plasma increases, very complex and dangerous instabilities arise, that is, unstable operating modes.
Why do we need this?
The main advantage of nuclear fusion is that it requires only very small amounts of substances that are very common in nature as fuel. The nuclear fusion reaction in the described installations can lead to the release of enormous amounts of energy, ten million times higher than the standard heat released during conventional chemical reactions (such as the combustion of fossil fuels). For comparison, we point out that the amount of coal required to power a thermal power plant with a capacity of 1 gigawatt (GW) is 10,000 tons per day (ten railway cars), and a fusion plant of the same power will consume only about 1 kilogram of the D+T mixture per day .
Deuterium is a stable isotope of hydrogen; In about one out of every 3,350 molecules of ordinary water, one of the hydrogen atoms is replaced by deuterium (a legacy from the Big Bang). This fact makes it easy to organize enough cheap to receive the required amount of deuterium from water. It is more difficult to obtain tritium, which is unstable (half-life is about 12 years, as a result of which its content in nature is negligible), however, as shown above, tritium will appear directly inside the thermonuclear installation during operation, due to the reaction of neutrons with lithium.
Thus, the initial fuel for a fusion reactor is lithium and water. Lithium is a common metal widely used in household appliances (cell phone batteries, etc.). The installation described above, even taking into account non-ideal efficiency, will be able to produce 200,000 kWh of electrical energy, which is equivalent to the energy contained in 70 tons of coal. The amount of lithium required for this is contained in one computer battery, and the amount of deuterium is in 45 liters of water. The above value corresponds to the current electricity consumption (calculated per person) in the EU countries over 30 years. The very fact that such an insignificant amount of lithium can ensure the generation of such an amount of electricity (without CO2 emissions and without the slightest air pollution) is a fairly serious argument for the fastest and most vigorous development of thermonuclear energy (despite all the difficulties and problems) and even without one hundred percent confidence in the success of such research.
Deuterium should last for millions of years, and reserves of easily mined lithium are sufficient to supply needs for hundreds of years. Even if lithium in rocks runs out, we can extract it from water, where it is found in concentrations high enough (100 times the concentration of uranium) to make its extraction economically viable.
An experimental thermonuclear reactor (International thermonuclear experimental reactor) is being built near the city of Cadarache in France. The main goal of the ITER project is to implement a controlled thermonuclear fusion reaction on an industrial scale.
Per unit weight of thermonuclear fuel, about 10 million times more energy is obtained than when burning the same amount of organic fuel, and about a hundred times more than when splitting uranium nuclei in the reactors of currently operating nuclear power plants. If the calculations of scientists and designers come true, this will give humanity an inexhaustible source of energy.
Therefore, a number of countries (Russia, India, China, Korea, Kazakhstan, USA, Canada, Japan, European Union countries) joined forces in creating the International Thermonuclear Research Reactor - a prototype of new power plants.
ITER is a facility that creates conditions for the synthesis of hydrogen and tritium atoms (an isotope of hydrogen), resulting in the formation of a new atom - a helium atom. This process is accompanied by a huge burst of energy: the temperature of the plasma in which the thermonuclear reaction occurs is about 150 million degrees Celsius (for comparison, the temperature of the Sun’s core is 40 million degrees). In this case, the isotopes burn out, leaving virtually no radioactive waste.
The scheme of participation in the international project provides for the supply of reactor components and financing of its construction. In exchange for this, each of the participating countries receives full access to all technologies for creating a thermonuclear reactor and to the results of all experimental work on this reactor, which will serve as the basis for the design of serial power thermonuclear reactors.
A reactor based on the principle of thermonuclear fusion does not have radioactive radiation and completely safe for the environment. It can be located almost anywhere in the world, and the fuel for it is ordinary water. Construction of ITER is expected to last about ten years, after which the reactor is expected to be in use for 20 years.
Russia's interests in the Council of the International Organization for the Construction of the ITER Thermonuclear Reactor in the coming years will be represented by Corresponding Member of the Russian Academy of Sciences Mikhail Kovalchuk - Director of the Kurchatov Institute, Institute of Crystallography of the Russian Academy of Sciences and Scientific Secretary of the Presidential Council on Science, Technology and Education. Kovalchuk will temporarily replace academician Evgeniy Velikhov in this post, who was elected chairman of the ITER International Council for the next two years and does not have the right to combine this position with the duties of an official representative of a participating country.
The total cost of construction is estimated at 5 billion euros, and the same amount will be required for trial operation of the reactor. The shares of India, China, Korea, Russia, the USA and Japan each account for approximately 10 percent of the total value, 45 percent comes from the countries of the European Union. However, the European states have not yet agreed on how exactly the costs will be distributed between them. Because of this, the start of construction was postponed to April 2010. Despite the latest delay, scientists and officials involved in ITER say they will be able to complete the project by 2018.
The estimated thermonuclear power of ITER is 500 megawatts. Individual magnet parts reach a weight of 200 to 450 tons. To cool ITER, 33 thousand cubic meters of water per day will be required.
In 1998, the United States stopped funding its participation in the project. After the Republicans came to power and rolling blackouts began in California, the Bush administration announced increased investment in energy. The United States did not intend to participate in the international project and was engaged in its own thermonuclear project. In early 2002, President Bush's technology adviser John Marburger III said that the United States had changed its mind and intended to return to the project.
In terms of the number of participants, the project is comparable to another major international scientific project - the International Space Station. The cost of ITER, which previously reached 8 billion dollars, then amounted to less than 4 billion. As a result of the withdrawal of the United States from participation, it was decided to reduce the reactor power from 1.5 GW to 500 MW. Accordingly, the price of the project has also decreased.
In June 2002, the symposium “ITER Days in Moscow” was held in the Russian capital. It discussed the theoretical, practical and organizational problems of reviving the project, the success of which can change the fate of humanity and give it a new type of energy, comparable in efficiency and economy only to the energy of the Sun.
In July 2010, representatives of the countries participating in the ITER international thermonuclear reactor project approved its budget and construction schedule at an extraordinary meeting held in Cadarache, France. The meeting report is available here.
At the last extraordinary meeting, project participants approved the start date for the first experiments with plasma - 2019. Full experiments are planned for March 2027, although the project management asked technical specialists to try to optimize the process and begin experiments in 2026. The meeting participants also decided on the costs of constructing the reactor, but the amounts planned to be spent on creating the installation were not disclosed. According to information received by the editor of the ScienceNOW portal from an unnamed source, by the time experiments begin, the cost of the ITER project could reach 16 billion euros.
The meeting in Cadarache also marked the first official working day for the new project director, Japanese physicist Osamu Motojima. Before him, the project had been led since 2005 by the Japanese Kaname Ikeda, who wished to leave his post immediately after the budget and construction deadlines were approved.
The ITER fusion reactor is a joint project of the European Union, Switzerland, Japan, USA, Russia, South Korea, China and India. The idea of creating ITER has been under consideration since the 80s of the last century, however, due to financial and technical difficulties, the cost of the project is constantly growing, and the construction start date is constantly being postponed. In 2009, experts expected that work on creating the reactor would begin in 2010. Later, this date was moved, and first 2018 and then 2019 were named as the launch time of the reactor.
Thermonuclear fusion reactions are reactions of fusion of nuclei of light isotopes to form a heavier nucleus, which are accompanied by a huge release of energy. In theory, fusion reactors can produce a lot of energy at low cost, but at the moment scientists spend much more energy and money to start and maintain the fusion reaction.
Thermonuclear fusion is a cheap and environmentally friendly way to produce energy. Uncontrolled thermonuclear fusion has been occurring on the Sun for billions of years - helium is formed from the heavy hydrogen isotope deuterium. This releases a colossal amount of energy. However, people on Earth have not yet learned to control such reactions.
The ITER reactor will use hydrogen isotopes as fuel. During a thermonuclear reaction, energy is released when light atoms combine into heavier ones. To achieve this, the gas must be heated to a temperature of over 100 million degrees - much higher than the temperature at the center of the Sun. Gas at this temperature turns into plasma. At the same time, atoms of hydrogen isotopes merge, turning into helium atoms with the release of a large number of neutrons. A power plant operating on this principle will use the energy of neutrons slowed down by a layer of dense material (lithium).
Why did the creation of thermonuclear installations take so long?
Why have such important and valuable installations, the benefits of which have been discussed for almost half a century, not yet been created? There are three main reasons (discussed below), the first of which can be called external or social, and the other two - internal, that is, determined by the laws and conditions of the development of thermonuclear energy itself.
1. For a long time, it was believed that the problem of the practical use of thermonuclear fusion energy did not require urgent decisions and actions, since back in the 80s of the last century, fossil fuel sources seemed inexhaustible, and environmental problems and climate change did not concern the public. In 1976, the U.S. Department of Energy's Fusion Energy Advisory Committee attempted to estimate the time frame for R&D and a demonstration fusion power plant under various research funding options. At the same time, it was discovered that the volume of annual funding for research in this direction is completely insufficient, and if the existing level of appropriations is maintained, the creation of thermonuclear installations will never be successful, since the allocated funds do not correspond even to the minimum, critical level.
2. A more serious obstacle to the development of research in this area is that a thermonuclear installation of the type under discussion cannot be created and demonstrated on a small scale. From the explanations presented below, it will become clear that thermonuclear fusion requires not only magnetic confinement of the plasma, but also sufficient heating of it. The ratio of expended and received energy increases at least in proportion to the square of the linear dimensions of the installation, as a result of which the scientific and technical capabilities and advantages of thermonuclear installations can be tested and demonstrated only at fairly large stations, such as the mentioned ITER reactor. Society was simply not ready to finance such major projects, there was not yet sufficient confidence in success.
3. The development of thermonuclear energy has been very complex, however (despite insufficient funding and difficulties in selecting centers for the creation of JET and ITER installations), clear progress has been observed in recent years, although an operating station has not yet been created.
The modern world is facing a very serious energy challenge, which can more accurately be called an “uncertain energy crisis.” The problem is related to the fact that reserves of fossil fuels may run out in the second half of this century. Moreover, burning fossil fuels may result in the need to somehow sequester and “store” the carbon dioxide released into the atmosphere (the CCS program mentioned above) to prevent major changes in the planet’s climate.
Currently, almost all the energy consumed by humanity is created by burning fossil fuels, and the solution to the problem may be associated with the use of solar energy or nuclear energy (the creation of fast breeder reactors, etc.). Global problem, driven by the growing population of developing countries and their need to improve living standards and increase the amount of energy produced, cannot be solved only on the basis of the approaches considered, although, of course, any development attempts should be encouraged alternative methods energy production.
Strictly speaking, we have a small choice of behavioral strategies and the development of thermonuclear energy is extremely important, even despite the lack of a guarantee of success. The Financial Times newspaper (dated January 25, 2004) wrote about this:
“Even if the costs of the ITER project significantly exceed the original estimate, they are unlikely to reach the level of $1 billion per year. This level of expenditure should be considered a very modest price to pay for a very reasonable opportunity to create a new source of energy for all of humanity, especially given the fact that already in this century we will inevitably have to give up the habit of wasteful and reckless burning of fossil fuels.”
Let's hope that there will be no major and unexpected surprises on the path to the development of thermonuclear energy. In this case, in about 30 years we will be able to supply electric current from it to energy networks for the first time, and in just over 10 years the first commercial thermonuclear power plant will begin to operate. It is possible that in the second half of this century, nuclear fusion energy will begin to replace fossil fuels and gradually begin to play an increasingly important role in providing energy to humanity on a global scale.
There is no absolute guarantee that the task of creating thermonuclear energy (as an effective and large-scale source of energy for all humanity) will be completed successfully, but the likelihood of success in this direction is quite high. Considering the enormous potential of thermonuclear stations, all costs for projects for their rapid (and even accelerated) development can be considered justified, especially since these investments look very modest against the backdrop of the monstrous global energy market ($4 trillion per year8). Meeting humanity's energy needs is a very serious problem. As fossil fuels become less available (and their use becomes undesirable), the situation is changing, and we simply cannot afford not to develop fusion energy.
To the question “When will thermonuclear energy appear?” Lev Artsimovich (a recognized pioneer and leader of research in this field) once responded that “it will be created when it becomes truly necessary for humanity”
ITER will be the first fusion reactor to produce more energy than it consumes. Scientists measure this characteristic using a simple coefficient they call "Q." If ITER achieves all its scientific goals, it will produce 10 times more energy than it consumes. The last device built, the Joint European Torus in England, is a smaller prototype fusion reactor that, in its final stages of scientific research, achieved a Q value of almost 1. This means that it produced exactly the same amount of energy as it consumed. ITER will go beyond this by demonstrating energy creation from fusion and achieving a Q value of 10. The idea is to generate 500 MW from an energy consumption of approximately 50 MW. Thus, one of the scientific goals of ITER is to prove that a Q value of 10 can be achieved.
Another scientific goal is that ITER will have a very long "burn" time - a pulse of extended duration up to one hour. ITER is a research experimental reactor that cannot produce energy continuously. When ITER starts operating, it will be on for one hour, after which it will need to be turned off. This is important because until now the standard devices we have created have been capable of having a burning time of several seconds or even tenths of a second - this is the maximum. The "Joint European Torus" reached its Q value of 1 with a burn time of approximately two seconds with a pulse length of 20 seconds. But a process that lasts a few seconds is not truly permanent. By analogy with starting a car engine: briefly turning on the engine and then turning it off is not yet real operation of the car. Only when you drive your car for half an hour will it reach a constant operating mode and demonstrate that such a car can actually be driven.
That is, from a technical and scientific point of view, ITER will provide a Q value of 10 and an increased burn time.
The thermonuclear fusion program is truly international and broad in nature. People are already counting on the success of ITER and are thinking about the next step - creating a prototype of an industrial thermonuclear reactor called DEMO. To build it, ITER needs to work. We must achieve our scientific goals because this will mean that the ideas we put forward are entirely feasible. However, I agree that you should always think about what comes next. In addition, as ITER operates for 25-30 years, our knowledge will gradually deepen and expand, and we will be able to more accurately outline our next step.
Indeed, there is no debate about whether ITER should be a tokamak. Some scientists pose the question quite differently: should ITER exist? Experts in different countries, developing their own, not so large-scale thermonuclear projects, argue that such a large reactor is not needed at all.
However, their opinion should hardly be considered authoritative. Physicists who have been working with toroidal traps for several decades were involved in the creation of ITER. The design of the experimental thermonuclear reactor in Karadash was based on all the knowledge gained during experiments on dozens of predecessor tokamaks. And these results indicate that the reactor must be a tokamak, and a large one at that.
JET At the moment, the most successful tokamak can be considered JET, built by the EU in the British town of Abingdon. This is the largest tokamak-type reactor created to date, the large radius of the plasma torus is 2.96 meters. The power of the thermonuclear reaction has already reached more than 20 megawatts with a retention time of up to 10 seconds. The reactor returns about 40% of the energy put into the plasma.
It is the physics of plasma that determines the energy balance,” Igor Semenov told Infox.ru. MIPT associate professor described what energy balance is with a simple example: “We have all seen a fire burn. In fact, it is not wood that burns there, but gas. The energy chain there is like this: the gas burns, the wood heats, the wood evaporates, the gas burns again. Therefore, if we throw water on a fire, we will abruptly take energy from the system for the phase transition of liquid water into a vapor state. The balance will become negative and the fire will go out. There is another way - we can simply take the firebrands and spread them in space. The fire will also go out. It’s the same in the thermonuclear reactor we are building. The dimensions are chosen to create an appropriate positive energy balance for this reactor. Sufficient to build a real nuclear power plant in the future, solving at this experimental stage all the problems that currently remain unresolved.”
The dimensions of the reactor were changed once. This happened at the turn of the 20th-21st centuries, when the United States withdrew from the project, and the remaining members realized that the ITER budget (by that time it was estimated at 10 billion US dollars) was too large. Physicists and engineers were required to reduce the cost of installation. And this could only be done due to size. The “redesign” of ITER was led by the French physicist Robert Aymar, who previously worked on the French Tore Supra tokamak in Karadash. The outer radius of the plasma torus has been reduced from 8.2 to 6.3 meters. However, the risks associated with the reduction in size were partly compensated for by several additional superconducting magnets, which made it possible to implement the plasma confinement mode, which was open and studied at that time.
Everyone has heard something about thermonuclear energy, but few can remember the technical details. Moreover, a short survey shows that many are confident that the very possibility of thermonuclear energy is a myth. I will give excerpts from one of the Internet forums, where a discussion suddenly broke out.
Pessimists:
“You can compare this to communism. There are more problems in this area than obvious solutions...”;
“This is one of the favorite topics for writing futuristic articles about a bright future...”
Optimists:
“This will happen because everything incredible turned out to be either initially impossible, or something whose progress was a critical factor for the development of technology...”;
“Thermonuclear energy is, guys, our inevitable future, and there’s no escape from it...”
Let's define the terms
– What is controlled thermonuclear fusion?
Elena Koresheva: Controlled thermonuclear fusion (CTF) is a field of research whose goal is the industrial use of the energy of thermonuclear fusion reactions of light elements.
Scientists around the world began this research when thermonuclear fusion in its uncontrolled stage was demonstrated during the explosion of the world's first hydrogen bomb near Semipalatinsk. The project of such a bomb was developed in the USSR in 1949 by Andrei Sakharov and Vitaly Ginzburg - the future Nobel laureates from FIAN - Physical Institute named after. P. N. Lebedev of the USSR Academy of Sciences, and on May 5, 1951, a decree of the Council of Ministers of the USSR was issued on the development of work on the thermonuclear program under the leadership of I. V. Kurchatov.
Unlike a nuclear bomb, the explosion of which releases energy as a result of fission atomic nucleus, in a hydrogen bomb a thermonuclear reaction occurs, the main energy of which is released during the combustion of a heavy isotope of hydrogen - deuterium.
Necessary conditions for starting a thermonuclear reaction are: heat(~100 million °C) and high fuel density - in a hydrogen bomb are achieved through the explosion of a small-sized nuclear fuse.
To implement the same conditions in the laboratory, that is, to move from uncontrolled thermonuclear fusion to controlled, FIAN scientists, academician N. G. Basov, laureate Nobel Prize 1964, and Academician O.N. Krokhin proposed using laser radiation. It was then, in 1964, at the Physical Institute. P. N. Lebedev, and then in other scientific centers of our country, research on CTS in the field of inertial plasma confinement was started. This direction is called inertial thermonuclear fusion, or ITS.
The classical fuel target used in ITS experiments is a system of nested spherical layers, the simplest version of which is an outer polymer shell and a cryogenic fuel layer formed on its inner surface. The basic idea of ITS is to compress five milligrams of a spherical fuel target to densities that are more than a thousand times the density of a solid.
Compression is carried out by the outer shell of the target, the substance of which, intensively evaporating under the influence of super-powerful laser beams or beams of high-energy ions, creates reactive recoil. The non-evaporated part of the shell, like a powerful piston, compresses the fuel located inside the target, and at the moment of maximum compression, the converging shock wave raises the temperature in the center of the compressed fuel so much that thermonuclear combustion begins.
It is assumed that targets will be injected into the ITS reactor chamber at a frequency of 1-15 Hz to ensure their continuous irradiation and, accordingly, a continuous sequence of thermonuclear microexplosions that provide energy. It's like an engine running internal combustion, only in such a process we can obtain many orders of magnitude more energy.
Another approach in CTS is associated with magnetic plasma confinement. This direction is called magnetic thermonuclear fusion (MTF). Research in this direction started ten years earlier, in the early 1950s. Institute named after I. V. Kurchatova is a pioneer of this research in our country.
– What is the ultimate goal of these studies?
Vladimir Nikolaev: The ultimate goal is the use of thermonuclear reactions in the production of electrical and thermal energy at modern high-tech, environmentally friendly generation facilities that use practically inexhaustible energy resources - inertial thermonuclear power plants. This new type of power plants should eventually replace the thermal power plants (TPPs) that we are used to using hydrocarbon fuels (gas, coal, fuel oil), as well as nuclear power plants(NPP). When will this happen? According to Academician L.A. Artsimovich, one of the leaders of CTS research in our country, thermonuclear energy will be created when it becomes truly necessary for humanity. This need becomes more and more urgent every year, and for the following reasons:
1. According to forecasts made in 2011 by the International Energy Agency (IEA), global annual electricity consumption between 2009 and 2035 will increase by more than 1.8 times - from 17,200 TWh per year to more than 31,700 TWh per year, with an annual growth rate of 2.4 percent.
2. The measures taken by humanity aimed at saving energy, the use of various kinds of energy-saving technologies in production and at home, alas, do not produce tangible results.
3. More than 80 percent of the world's energy consumption now comes from burning fossil fuels - oil, coal and natural gas. The predicted depletion of reserves of this fossil fuel in fifty to a hundred years, as well as the uneven location of deposits of these fossils, the remoteness of these deposits from power plants, requiring additional costs for transporting energy resources, the need in some cases to incur additional very significant costs for enrichment and for preparing fuel for burning.
4. The development of renewable energy sources based on solar energy, wind energy, hydropower, biogas (currently these sources account for about 13-15 percent of energy consumed in the world) is limited by such factors as dependence on the climatic characteristics of the location of the power plant, dependence on time of year and even time of day. Here we should also add the relatively small nominal capacities of wind turbines and solar stations, the need to allocate significant areas for wind farms, the instability of wind and solar power plants, creating technical difficulties in integrating these objects into the operating mode of the electric power system, etc.
– What are the forecasts for the future?
Vladimir Nikolaev: The main candidate for a leading position in the energy sector of the future is nuclear energy - the energy of nuclear power plants and the energy of controlled thermonuclear fusion. If currently about 18 percent of the energy consumed in Russia is the energy of nuclear power plants, then controlled thermonuclear fusion has not yet been implemented on an industrial scale. An effective solution to the practical use of CTS will allow you to master an environmentally friendly, safe and practically inexhaustible source of energy.
Where is the real implementation experience?
– Why does TTS wait so long for its implementation? After all, the first work in this direction was carried out by Kurchatov back in the 1950s?
Vladimir Nikolaev: For a long time, it was generally believed that the problem of the practical use of thermonuclear fusion energy did not require urgent solutions, since back in the 80s of the last century, fossil fuel sources seemed inexhaustible, and environmental problems and climate change were not as pressing as they are now.
In addition, mastering the problem of CTS initially required the development of completely new scientific directions - physics of high-temperature plasma, physics of ultra-high energy densities, physics of anomalous pressures. It required the development of computer technology and the development of a number of mathematical models behavior of matter when starting thermonuclear reactions. To verify the theoretical results, it was necessary to make a technological breakthrough in the creation of lasers, ion and electronic sources, fuel microtargets, diagnostic equipment, as well as to create large-scale laser and ion installations.
And these efforts were not in vain. More recently, in September 2013, in US experiments at the powerful NIF laser facility, the so-called “scientific breakeven” was demonstrated for the first time: the energy released in thermonuclear reactions exceeded the energy invested in compressing and heating the fuel in the target according to the ITS scheme . This serves as an additional incentive to accelerate the development of existing programs around the world aimed at demonstrating the possibility of commercial use of a fusion reactor.
According to various forecasts, the first prototype of a thermonuclear reactor will be launched before 2040, as a result of a number of international projects and government programs, including the international ITER reactor based on MTS, as well as national programs for building reactors based on ITS in the USA, Europe and Japan. Thus, from the launch of uncontrolled thermonuclear fusion processes to the launch of the first CTS power plant, seventy to eighty years will pass.
Regarding the duration of the implementation of the CTS, I would like to clarify that 80 years is by no means a long time. For example, eighty-two years passed from the invention of the first voltaic cell by Alessandro Volta in 1800 to the launch of the first prototype power plant by Thomas Edison in 1882. And if we talk about the discovery and first studies of electrical and magnetic phenomena by William Gilbert (1600), then more than two centuries passed before the practical application of these phenomena.
– What are the scientific and practical directions for using inertial controlled thermonuclear fusion?
Elena Koresheva: The ITS reactor is an environmentally friendly source of energy that can compete economically with traditional fossil fuel sources and nuclear power plants. In particular, the forecast of the US Livermore National Laboratory predicts a complete abandonment of modern nuclear power plants by the US energy sector and their complete replacement by ITS systems by 2090.
Technologies developed during the creation of the ITS reactor can be used in various industries of the country.
But first of all, it is necessary to create a mechanical mock-up of the reactor, or SMR, which will allow optimizing the basic processes associated with the frequency and synchronicity of delivery of fuel targets to the thermonuclear combustion zone. Launching an SMR and conducting test experiments on it is a necessary stage in the development of elements of a commercial reactor.
And finally, the ITS reactor is a powerful source of neutrons with a neutron yield of up to 1020 n/sec, and the neutron flux density in it reaches colossal values and can exceed 1020 n/sec-cm 2 on average and 1027 n/sec-cm 2 in pulse near the reaction zone. The ITS reactor, as a powerful source of neutrons, is a unique research tool in such areas as fundamental research, energy, nano- and biotechnology, medicine, geology, and safety issues.
As for the scientific areas of using ITS, they include the study of physics related to the evolution of supernovae and other astrophysical objects, the study of the behavior of matter under extreme conditions, the production of transuranium elements and isotopes that do not exist in nature, the study of the physics of interaction of laser radiation with plasma, and much more. other.
– In your opinion, is there any need to switch to CTS as an alternative source of energy?
Vladimir Nikolaev: There are several aspects to the need for such a transition. First of all, this is the environmental aspect: the fact of the detrimental impact of traditional energy production technologies, both hydrocarbon and nuclear, on the environment is well known and proven.
We should not forget the political aspect of this problem, because the development alternative energy will allow the country to claim world leadership and actually dictate prices for fuel resources.
Next, we note the fact that it is becoming more and more expensive to extract fuel resources, and their combustion is becoming less and less feasible. As D.I. Mendeleev said, “to drown with oil is the same as to drown with banknotes.” Therefore, the transition to alternative technologies in the energy sector will allow preserving the country’s hydrocarbon resources for their use in the chemical and other industries.
And finally, as the population size and density are constantly growing, it is becoming increasingly difficult to find areas for the construction of nuclear power plants and state district power plants where energy production would be profitable and safe for the environment.
Thus, from the point of view of social, political, economic or environmental aspects of creating controlled thermonuclear fusion, no questions arise.
The main difficulty is that to achieve the goal it is necessary to solve many problems that have not previously faced science, namely:
Understand and describe the complex physical processes occurring in a reacting fuel mixture,
Select and test suitable construction materials,
Develop powerful lasers and X-ray sources,
Develop pulsed power systems capable of creating powerful particle beams,
Develop a technology for mass production of fuel targets and a system for their continuous supply into the reactor chamber synchronously with the arrival of laser radiation pulses or particle beams, and much more.
Therefore, the problem of creating a Federal target state program for the development of inertial controlled thermonuclear fusion in our country, as well as issues of its financing, comes to the fore.
– Will controlled thermonuclear fusion be safe? What consequences for the environment and population could result from an emergency situation?
Elena Koresheva: Firstly, the possibility of a critical accident at a thermonuclear power plant is completely excluded due to the principle of its operation. The fuel for thermonuclear fusion does not have a critical mass, and, unlike nuclear power plant reactors, in the UTS reactor the reaction process can be stopped in a split second in the event of any emergency situations.
Structural materials for a thermonuclear power plant will be selected in such a way that they will not form long-lived isotopes due to activation by neutrons. This means that it is possible to create a “clean” reactor, unencumbered by the problem of long-term storage of radioactive waste. According to estimates, after shutting down an exhausted thermonuclear power plant, it can be disposed of in twenty to thirty years without the use of special protective measures.
It is important to emphasize that thermonuclear fusion energy is a powerful and environmentally friendly source of energy, ultimately using simple sea water as fuel. With this energy extraction scheme, neither greenhouse effects arise, as when burning organic fuel, nor long-lived radioactive waste, as when operating nuclear power plants.
A fusion reactor is much safer than a nuclear reactor, primarily in terms of radiation. As mentioned above, the possibility of a critical accident at a thermonuclear power plant is excluded. On the contrary, at a nuclear power plant there is the possibility of a major radiation accident, which is associated with the very principle of its operation. The most striking example is accidents on Chernobyl nuclear power plant in 1986 and at the Fukushima-1 nuclear power plant in 2011. The amount of radioactive substances in the CTS reactor is small. The main radioactive element here is tritium, which is weakly radioactive, has a half-life of 12.3 years and is easily disposed of. In addition, the design of the UTS reactor contains several natural barriers that prevent the spread of radioactive substances. The service life of a nuclear power plant, taking into account the extension of its operation, ranges from thirty-five to fifty years, after which the station must be decommissioned. A large amount of highly radioactive materials remains in the reactor of a nuclear power plant and around the reactor, and it will take many decades to wait for the radioactivity to decrease. This leads to the withdrawal of vast territories and material assets from economic circulation.
We also note that from the point of view of the possibility of an emergency tritium leak, future stations based on ITS undoubtedly have an advantage over stations based on magnetic thermonuclear fusion. In ITS stations, the amount of tritium simultaneously present in the fuel cycle is calculated in grams, maximum tens of grams, while in magnetic systems this amount should be tens of kilograms.
– Are there already installations operating on the principles of inertial thermonuclear fusion? And if so, how effective are they?
Elena Koresheva: In order to demonstrate the energy of thermonuclear fusion obtained using the ITS scheme, pilot laboratory installations have been built in many countries around the world. The most powerful among them are the following:
Since 2009, the Lawrence Livermore National Laboratory in the United States has operated a NIF laser facility with a laser energy of 1.8 MJ, concentrated in 192 beams of laser radiation;
In France (Bordeaux) introduced powerful installation LMJ with laser energy of 1.8 MJ in 240 laser beams;
In the European Union, a powerful laser installation HiPER (High Power laser Energy Research) with an energy of 0.3-0.5 MJ is being created, the operation of which requires the production and delivery of fuel targets with a high frequency of >1 Hz;
The US Laser Energy Laboratory operates an OMEGA laser installation, the laser energy of 30 kJ of energy is concentrated in sixty beams of laser radiation;
The US Naval Laboratory (NRL) has built the world's most powerful NIKE krypton-fluorine laser with an energy of 3 to 5 kJ in fifty-six laser beams;
In Japan, at the Laboratory of Laser Technology at Osaka University, there is a multi-beam laser installation GEKKO-XII, laser energy - 15-30 kJ;
In China, there is an SG-III installation with a laser energy of 200 kJ in sixty-four laser beams;
The Russian Federal Nuclear Center - All-Russian Research Institute of Experimental Physics (RFNC-VNIIEF, Sarov) operates ISKRA-5 (twelve beams of laser radiation) and LUCH (four beams of laser radiation) installations. The laser energy in these installations is 12-15 kJ. Here, in 2012, construction began on a new UFL-2M installation with a laser energy of 2.8 MJ in 192 beams. It is planned that the launch of this, the most powerful laser in the world, will occur in 2020.
The purpose of the operation of the listed ITS installations is to demonstrate the technical profitability of ITS when the energy released in thermonuclear reactions exceeds the entire invested energy. To date, the so-called scientific breakeven, that is, the scientific profitability of ITS, has been demonstrated: the energy released in thermonuclear reactions for the first time exceeded the energy invested in compressing and heating the fuel.
– In your opinion, installations using controlled thermonuclear fusion can be economically profitable today? Can they really compete with existing stations?
Vladimir Nikolaev: Controlled thermonuclear fusion is a real competitor to such proven energy sources as hydrocarbon fuels and nuclear power plants, since the fuel reserves for the UTS power plant are practically inexhaustible. The amount of heavy water containing deuterium in the world's oceans is about ~1015 tons. Lithium, from which the second component of thermonuclear fuel, tritium, is produced, is already produced in the world in tens of thousands of tons per year and is inexpensive. Moreover, 1 gram of deuterium can provide 10 million times more energy than 1 gram of coal, and 1 gram of a deuterium-tritium mixture will provide the same energy as 8 tons of oil.
In addition, fusion reactions are a more powerful source of energy than fission reactions of uranium-235: the thermonuclear fusion of deuterium and tritium releases 4.2 times more energy than the fission of the same mass of uranium-235 nuclei.
Waste disposal at nuclear power plants is a complex and expensive technological process, while a thermonuclear reactor is practically waste-free and, accordingly, clean.
We also note an important aspect of the operational characteristics of ITES, such as the adaptability of the system to changes in energy regimes. Unlike nuclear power plants, the process of reducing power in ITES is primitively simple - it is enough to reduce the frequency of supplying thermonuclear fuel targets into the reactor chamber. Hence, another important advantage of ITES in comparison with traditional nuclear power plants: ITES is more maneuverable. Perhaps in the future this will make it possible to use powerful ITES not only in the “base” part of the power system load schedule, along with powerful “base” hydroelectric power plants and nuclear power plants, but also to consider ITES as the most maneuverable “peaking” power plants that ensure stable operation of large energy systems. Or use ITES during the period of daily load peaks of the electrical system, when the available capacities of other stations are not enough.
– Are they held today in Russia or other countries? scientific developments to create a competitive, cost-effective and safe inertial thermonuclear power station?
Elena Koresheva: In the USA, Europe and Japan, there are already long-term national programs to build an ITS-based power plant by 2040. It is planned that access to optimal technologies will occur by 2015-2018, and demonstration of the operation of a pilot plant in continuous power generation mode by 2020-2025. China has a program to build and launch in 2020 a reactor-scale laser facility SG-IV with a laser energy of 1.5 MJ.
Let us recall that in order to ensure a continuous mode of energy generation, the supply of fuel to the center of the ITES reactor chamber and the simultaneous supply of laser radiation there must be carried out at a frequency of 1-10 Hz.
To test reactor technologies, the US Naval Laboratory (NRL) has created the ELEKTRA installation, operating at a frequency of 5 Hz with a laser energy of 500-700 Joules. By 2020, it is planned to increase laser energy by a thousand times.
A powerful pilot ITS installation with an energy of 0.3-0.5 MJ, which will operate in frequency mode, is being created within the framework of the European HiPER project. The purpose of this program: to demonstrate the possibility of obtaining thermonuclear fusion energy in a frequency mode, as is typical for the operation of an inertial thermonuclear power station.
We also note here state project Republic of South Korea to create an innovative high-power frequency laser at the Korean Progressive Institute of Physics and Technology KAIST.
In Russia, at the Physical Institute named after. P. N. Lebedev, a unique FST method has been developed and demonstrated, which is a promising way to solve the problem of frequency formation and delivery of cryogenic fuel targets to an ITS reactor. Laboratory equipment has also been created here that simulates the entire process of preparing a reactor target - from filling it with fuel to carrying out frequency delivery to the laser focus. At the request of the HiPER program, FIAN specialists developed a design for a target factory operating on the basis of the FST method and ensuring the continuous production of fuel targets and their frequency delivery to the focus of the HiPER experimental camera.
In the USA there is long-term program LIFE, which aims to build the first ITS power plant by 2040. The LIFE program will be developed on the basis of the powerful NIF laser facility operating in the United States with a laser energy of 1.8 MJ.
Note that in recent years, research on the interaction of very intense (1017-1018 W/cm 2 and higher) laser radiation with matter has led to the discovery of new, previously unknown physical effects. This has revived hopes for the implementation of a simple and effective way ignition of a thermonuclear reaction in uncompressed fuel using plasma blocks (the so-called side-on ignition), which was proposed more than thirty years ago, but could not be implemented at the technological level then available. To implement this approach, a laser with a picosecond pulse duration and a power of 10-100 petaWatt is required. Currently, research on this topic is being intensively conducted all over the world; lasers with a power of 10 petawatts (PW) have already been built. For example, this is the VULCAN laser facility at the Rutherford and Appleton laboratory in the UK. Calculations show that when using such a laser in ITS, ignition conditions for neutronless reactions, such as proton-boron or proton-lithium, are quite achievable. In this case, in principle, the problem of radioactivity is eliminated.
Within the framework of CTS, an alternative technology to inertial thermonuclear fusion is magnetic thermonuclear fusion. This technology is being developed around the world in parallel with ITS, for example, within the framework of the international ITER program. The construction of the international experimental thermonuclear reactor ITER based on the TOKAMAK type system is carried out in the south of France at the Cadarache research center. On the Russian side, many enterprises of Rosatom and other departments are involved in the ITER project under the overall coordination of the “ITER Project Center” established by Rosatom. The purpose of creating ITER is to study the conditions that must be met during the operation of fusion power plants, as well as to create on this basis cost-effective power plants that will be larger in size than ITER by at least 30 percent in each dimension.
There are prospects in Russia
– What could prevent the successful construction of a thermonuclear power plant in Russia?
Vladimir Nikolaev: As already mentioned, there are two directions of development of CTS: with magnetic and inertial plasma confinement. To successfully solve the problem of building a thermonuclear power plant, both directions must be developed in parallel within the framework of the relevant federal programs, as well as Russian and international projects.
Russia is already participating in the international project to create the first prototype of the UTS reactor - this is the ITER project related to magnetic thermonuclear fusion.
As for a power plant based on ITS, there is no such state program in Russia yet. Lack of funding in this area could lead to Russia's significant lag in the world and the loss of existing priorities.
On the contrary, subject to appropriate financial investments, real prospects for building an inertial thermonuclear power plant, or ITES, are opening up on Russian territory.
– Are there prospects for building an inertial thermonuclear power station in Russia, subject to adequate financial investments?
Elena Koresheva: There are prospects. Let's look at this in more detail.
ITES consists of four fundamentally necessary parts:
1. Combustion chamber, or reactor chamber, where thermonuclear microexplosions occur and their energy is transferred to the coolant.
2. Driver – a powerful laser, or ion accelerator.
3. Target factory - a system for preparing and introducing fuel into the reactor chamber.
4. Thermal and electrical equipment.
The fuel for such a station will be deuterium and tritium, as well as lithium, which is part of the wall of the reactor chamber. Tritium does not exist in nature, but in a reactor it is formed from lithium when it interacts with neutrons from thermonuclear reactions. The amount of heavy water containing deuterium in the World Ocean, as already mentioned here, is about ~1015 tons. From a practical point of view, this is an infinite value! Extracting deuterium from water is a well-established and cheap process. Lithium is an accessible and fairly cheap element found in the earth’s crust. When lithium is used in ITES, it will last for several hundred years. In addition, in the longer term, as the technology of powerful drivers (i.e., lasers, ion beams) develops, it is planned to carry out a thermonuclear reaction on pure deuterium or on a fuel mixture containing only a small amount of tritium. Consequently, the cost of fuel will make a very small contribution, less than 1 percent, to the cost of the energy produced by a fusion power plant.
The combustion chamber of an ITES is, roughly speaking, a 10-meter sphere, on the inner wall of which circulation of liquid, and in some versions of stations, powdery coolant, such as lithium, is ensured, which is simultaneously used both to remove the energy of a thermonuclear micro-explosion and to produce tritium. In addition, the chamber provides the required number of input windows for entering targets and driver radiation. The design is reminiscent of the buildings of powerful nuclear reactors or some industrial chemical synthesis plants, the practical experience of which is available. There are still many problems to be solved, but there are no fundamental restrictions. Some developments on materials of this design and individual components already exist, in particular, in the ITER project.
Thermal and electrical equipment are fairly well-developed technical devices that have been used at nuclear power plants for a long time. Naturally, at a thermonuclear station these systems will have comparable costs.
As for the most complex ITES systems - drivers and target factories, in Russia there is a good foundation necessary for the adoption of a state program for ITES and the implementation of a number of projects both in collaboration with Russian institutions and within the framework of international cooperation. From this point of view, an important point is those methods and technologies that have already been developed in Russian research centers.
In particular, the Russian Federal Nuclear Center in Sarov has priority developments in the field of creating powerful lasers, production of single fuel targets, diagnostics of laser systems and thermonuclear plasma, as well as computer modeling of processes occurring in ITS. Currently, the RFNC-VNIIEF is implementing the UFL-2M program to build the world's most powerful laser with an energy of 2.8 MJ. A number of other Russian organizations also take part in the program, including the Physics Institute named after. P. N. Lebedeva. The successful implementation of the UFL-2M program, launched in 2012, is another big step Russia on the path to developing thermonuclear fusion energy.
At the Russian Scientific Center "Kurchatov Institute" (Moscow), together with the Polytechnic University of St. Petersburg, research was carried out in the field of delivery of cryogenic fuel using a pneumatic injector, which are already used in magnetic thermonuclear fusion systems, such as TOKAMAK; various systems for protecting fuel targets during their delivery to the ITS reactor chamber were studied; The possibility of widespread practical use of ITS as a powerful source of neutrons was investigated.
At the Physical Institute named after. P. N. Lebedev RAS (Moscow) there are the necessary developments in the field of creating a reactor target factory. Developed here unique technology frequency production of fuel targets and a prototype of a target factory operating at a frequency of 0.1 Hz was created. Various target delivery systems have also been created and studied here, including a gravitational injector, an electromagnetic injector, as well as new transportation devices based on quantum levitation. Finally, technologies for high-precision target quality control and diagnostics during delivery have been developed here. Some of this work was carried out in collaboration with the previously mentioned ITS centers within the framework of ten international and Russian projects.
However a necessary condition implementation of methods and technologies developed in Russia is the adoption of a long-term Federal target program for ITS and its financing.
– What, in your opinion, should be the first step towards the development of thermonuclear energy based on ITS?
Vladimir Nikolaev: The first step could be the project “Development of a mechanical model of a reactor and a prototype of a TARGET FACTORY for the frequency replenishment of a power station operating on the basis of inertial thermonuclear fusion with cryogenic fuel,” proposed by the Center for Energy Efficiency “INTER RAO UES” together with the Physical Institute named after. P. N. Lebedeva and National Research Center Kurchatov Institute. The results obtained in the project will allow Russia not only to gain a stable priority in the world in the field of ITS, but also to come close to building a commercial power plant based on ITS.
It is already clear that future ITES must be built with a large unit capacity - at least several gigawatts. Under this condition, they will be quite competitive with modern nuclear power plants. In addition, future thermonuclear energy will eliminate the most pressing problems of nuclear energy - the danger of a radiation accident, the disposal of high-level waste, the rise in cost and depletion of fuel for nuclear power plants, etc. Note that an inertial thermonuclear power plant with a thermal power of 1 gigawatt (GW) is equivalent from the point of view of radiation hazard fission reactor with a power of only 1 kW!
– In which regions is it advisable to locate ITES? Place of inertial thermonuclear power station in energy system Russia?
Vladimir Nikolaev: As mentioned above, in contrast to thermal power plants (state district power plants, combined heat and power plants, combined heat and power plants), the location of ITES does not depend on the location of the fuel sources. Its annual fuel supply requirement is approximately 1 ton, and these are safe and easily transportable materials.
Nuclear reactors cannot be located near densely populated areas due to the risk of an accident. These restrictions, characteristic of nuclear power plants, are absent when choosing the location of the ITES. ITES can be located near large cities and industrial centers. This removes the problem of connecting the station to a unified power system. In addition, for ITES there are no disadvantages associated with the complexity of construction and operation of nuclear power plants, as well as with the difficulties associated with the processing and disposal of nuclear waste and the dismantling of nuclear power plant facilities.
ITES can be located in remote, sparsely populated and hard-to-reach areas and operate autonomously, providing energy-intensive technological processes, such as, for example, the production of aluminum and non-ferrous metals in Eastern Siberia, the Magadan region and Chukotka, Yakut diamonds and much more.