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Gold holraum laser fusion

National complex of laser thermonuclear reactions (National Ignition Facility, NIF) in the United States, it is called a dual-purpose laser fusion. It is designed to help the US military maintain its nuclear arsenals in combat-ready condition in the face of a moratorium on nuclear testing, and it also offers breakthrough discoveries that can provide civilization with a sea of ​​​​clean and cheap energy.

According to the press, things at NIF are unfolding as well as possible. But the auditors of the US General Accounting Service (GAO, analogue of the Russian Accounts Chamber) there is doubt about this, which they shared with Congress in report number GAO-10-488.

NIF, NIC and NNSA

In March 2009, the US National Nuclear Security Administration (NNSA) completed construction of NIF, a $3.5 billion project at Lawrence Livermore National Laboratory. The estimate includes $2.2 billion for the actual construction and $1.3 billion for the assembly and installation of 192 lasers and related equipment.

Management plans to create extreme high pressures and temperatures characteristic of nuclear explosions. If everything goes well, the new installation will allow the Americans to study the characteristics of nuclear explosive devices without testing them, prohibited by the terms of the moratorium adopted in the United States in 1992.

NNSA rightly calls laser fusion a "critical component" of a large-scale program to maintain the combat readiness of American nuclear arsenals. Military tasks will be a top priority for NIF, but the military department is ready to provide facilities for civilian researchers as well.

The design and construction of the NIF is directly the responsibility of Lawrence Livermore National Laboratory. The first theoretical studies aimed at preparing for the emergence of NIF date back to March 1997. In 2005, the NNSA, following congressional directives, created NIC (National Ignition Campaign) and instructed her to oversee the management of the project. In addition, for third-party control over the project are invited independent experts and expert groups.

Lasers and hohlraum

The technology used in NIF can be called "laser fusion". In American literature, the term "ignition" stuck behind it. Once everything is ready, NIF operators must simultaneously focus 192 laser beams on targets smaller than a dime. The total beam energy will be 1.8 MJ.

In one working cycle lasting about one millionth of a second, the beams must pass through a series of optical multipliers, and then focus on a microscopic target. The latter will be located inside a spherical chamber 10 meters high.

NIF installation diagram - GAO auditors drawing.

The target itself, in turn, is a hollow golden cylinder. He is called German word"holraum" (hohlraum) is a cavity whose walls are in radiation equilibrium with the cavity. In the holraum, like in a nesting doll, there is a fuel capsule the size of a peppercorn. It consists of a frozen layer of deuterium and tritium surrounding a cooled gaseous mixture of the same isotopes.

During operation, the NIF lasers must quickly heat up the inner walls of the hohlraum, which will convert the laser energy into x-rays. In its turn, X-rays must quickly heat the outer surface of the fuel capsule. With proper heating, the capsule should collapse with a force comparable to that arising during a rocket launch, that is, an inward explosion (implosion) of the deuterium-tritium layer should occur.

If the implosion proceeds symmetrically and at the desired speed, then the deuterium and tritium atoms will be forced into a fusion reaction lasting 10 trillionths of a second. The temperatures that will be created in the fuel capsule are expected to be in the order of 100 million degrees - that is, it will be hotter in the capsule than in the center of the Sun.

Schematic of energy transfer in hohlraum - drawing by GAO auditors.
Click the left mouse button to view in full scale.

Preliminary tests to substantiate the processes incorporated in the NIF facility were carried out at the Laser Energy Laboratory of the University of Rochester (New York). The lab's OMEGA and OMEGA EP laser systems are the workhorse of all NNSA laser fusion research today. Prior to the creation of NIF, they held the world record for laser beam energy.

Targets, hohlraums and other related equipment for the NIF are supplied by the Californian company General Atomics. The Los Alamos National Laboratory is responsible for the diagnostic systems, while the Sandia Lab is responsible for supporting research at the Z Machine, which is capable of converting electromagnetic radiation into X-rays.

Technical problems

Will the creation of NIF lead to success and will American scientists be able to ignite a thermonuclear reaction using lasers? GAO auditors dryly recall the conclusions of the independent JASON group, which list the technical problems facing NIF developers.

One of the main tasks is to minimize losses laser radiation, that is, to significantly reduce the fraction of energy that will pass by the hohlraum or be reflected from its walls. If the reflection threatens with a simple loss of energy, then each missed beam will negatively affect the symmetry of the compression of the fuel capsule, thereby casting doubt on the fact of the initiation of a thermonuclear reaction.

Even the most accurate aiming of the laser beam does not guarantee complete success. Under the influence of laser radiation, the ionization process starts inside the hohlraum, and the resulting charged gas interferes with the energy transfer processes. In short, as a result of the interaction of ionized particles and laser beams, part of the energy that has arrived in the hohlraum will be taken back out of it.

Scientists call this process "laser-plasma instability." (laser-plasma instability). In addition to energy loss, it also leads to unwanted interference between laser beams, which will adversely affect the symmetry of the implosion.

The second major problem with NIF is related to implosion speed. To initiate a thermonuclear reaction, the fuel capsule must be compressed 40,000 times its original size. In this case, the capsule must maintain a spherical shape. Moreover, implosion must occur at a given rate, otherwise it will not be possible to create the pressures necessary to start the synthesis of light nuclei.

If the surface of the fuel capsule is not smooth enough, or if the x-rays are not uniformly incident on the capsule, finger-like protrusions will begin to form on the capsule. As shown by the results of calculations for mathematical models, the formation of protrusions will be the result of hydrodynamic instabilities that occur when materials with different densities come into contact. If there are too many protrusions, then the thermonuclear reaction will not go on, since the temperature inside the capsule will decrease due to the protrusions.

The finger-like protrusions on the surface of the fuel capsule are a drawing by the GAO auditors.
Click the left mouse button to view in full scale.

In addition to these two problems, the creators of NIF also face more traditional, but no less serious difficulties. So, they need to provide reliable control over the state of the optics, which, of course, will eventually be damaged by laser beams passing through it.

At first, there will be few such damages, but over time, their number will begin to grow, and if the total percentage of damages exceeds a certain limit, then the operation of the NIF at nominal parameters will be impossible.

To the credit of the creators of NIF, they do not get out of trouble. The hohlraum project was completely redone, and its new design promises to minimize laser energy loss. Coverings of the entry points of laser beams were removed from his project as soon as it turned out that a seemingly good idea to arrange in a special way the places where the beams hit the target leads to a sharp increase in "laser-plasma" instabilities.

After a long search, scientists settled on helium as the material that fills the hohlraum. The original project was supposed to use a mixture of hydrogen and helium. These and other modifications were tested in combat during the first experiments on the NIF, performed in 2009. The results obtained are considered satisfactory, and there are hopes to avoid instabilities when operating at rated power.

Understanding of implosion processes should improve after completion of a series of computer simulations in two- and three-dimensional models. In addition, hydrodynamic instability is being actively studied at the already mentioned OMEGA complex. NIF staff also hope that they will be able to provide control over the condition of the optics.

The work of NIF with a total laser beam energy of 1.8 MJ has been postponed to 2011. Until the end of 2010, the unit will operate with energies of 1.2-1.3 MJ. According to experts, at an energy of 1.2 MJ, energy losses due to instabilities did not exceed 6% in the first experiments, despite the fact that the project allows 15% losses.

The first inclusions also led to the first losses in optics. In March 2009, part of the beams was unexpectedly reflected on the way to the target. A "successful" volley, combined with a design error, disabled 4% of total mirrors in the system. Fortunately, the "execution" took place at low beam energies, otherwise the consequences could have been even worse.

Installing NIF step by step is moving towards par. The most recent results from the December 2009 experiments were obtained with a laser energy of 1.2 MJ.

Independent experts urge caution. They predict that NIF will inevitably face new technological and physical challenges that are impossible even to predict at this stage. And GAO auditors are wondering if the current schedule is realistic, according to which the first laser fusion reaction will occur in 2012?

(UTS) - the process of fusion of light atomic nuclei, taking place with the release of energy at high temp-pax under controlled controlled conditions. TTS has not yet been implemented. To carry out fusion reactions, the reacting nuclei must be brought together at a distance of about 10 -11 cm, after which the process of their fusion occurs with a noticeable probability due to tunnel effect. To overcome the potential barrier to colliding light nuclei should be reported ~ 10 keV, which corresponds to a temperature of ~ 10 8 K. With an increase in the charge of the nuclei (serial number Z), their Coulomb repulsion increases and the amount of energy required for the reaction increases. Eff. cross sections of (p, p)-reactions due to weak interactions, very small. Reactions between heavy isotopes of hydrogen (deuterium and tritium) are due to strong interaction and have 22–23 orders of magnitude higher (see Fig. thermonuclear reactions). Differences in the values ​​of energy release in fusion reactions do not exceed one order of magnitude. With the fusion of deuterium and tritium nuclei, it is 17.6 MeV. The large number of these reactions and the relatively high energy release make an equal-component mixture of deuterium and tritium the most promising for solving the problem of controlled fusion. Tritium is radioactive ( half life 12.5 years), does not occur in nature. Therefore, to ensure the work thermonuclear reactor, used as nuclear fuel, the possibility of its reproduction should be provided. For this purpose, the working zone of the reactor can be surrounded by a layer of a light isotope of lithium, in which the reaction will take place

Eff. cross section of thermonuclear reactions increases rapidly with temperature, but even in the optimum. conditions remains incomparably less eff. cross sections of atomic collisions. For this reason, fusion reactions must take place in a fully ionized plasma heated to a high temperature, where ionization and excitation of atoms are absent and deuteron-deuteron or deuton-triton collisions sooner or later end in nuclear fusion.

Successful operation and further development of any of the listed systems is possible only if the initial structure is macroscopically stable, retaining the given shape during the entire time required for the reaction to proceed. In addition, in the plasma, those microscopic ones must be suppressed. instability, with the emergence and development of which particles cease to be in energy equilibrium and the fluxes of particles and heat across the lines of force increase sharply compared to their theoretical. value. It was in the direction of stabilization of plasma instabilities of various types that the main magnetic research. systems since 1952, and this work cannot be considered complete yet.

Ultra-fast control systems with inertial confinement. Difficulties associated with magnet. Plasma confinement can, in principle, be circumvented by "burning" thermonuclear fuel in extremely short times, when the heated fuel does not have time to scatter from the reaction zone. According to the Lawson criterion, the implementation of CTS with this method of combustion can be achieved only at a very high density of the working substance. To avoid the situation thermo nuclear explosion high power, it is necessary to use very small portions of fuel: the initial thermonuclear fuel should have the form of small grains (several mm in diameter), prepared from a mixture of solid deuterium and tritium, injected into the reactor before each of its working cycles. Ch. the problem lies in the rapid supply of the necessary energy to heat the grains of fuel. The solution to this problem is assigned to the use of laser radiation (see. laser thermonuclear fusion ) or intense focused beams of fast charge. particles. Research in the field of CTS using laser heating began in 1964; the use of beams of heavy and light ions is at an even higher early stage study (see Ionic thermonuclear fusion).

Energy W, which must be brought to a grain of fuel to ensure the operation of the installation in the reactor mode, as follows from a simple calculation, is inversely proportional to the square of the density of deuterium-tritium fuel. Estimates show that admissible values W are obtained only in the case of a sharp, 10 2 -10 3 times, increase in the density of thermonuclear fuel compared to the initial density of the solid (d, t) target. Such high compression ratios required to obtain such high densities, turn out to be achievable by evaporation of the surface layers of a symmetrically irradiated target and reactive compression of its internal. zones. To do this, the input power must be programmed in a certain way in time. Dr. The possibilities lie in programming the radial distribution of matter density and in the use of complex multi-shell targets. The required energy is estimated at ~10 6 -10 7 J, which lies within the current. possibilities of laser technology. An analysis of systems with ion beams leads to figures of the same scale.

Difficulties and prospects. Research in the field of CTS faces great difficulties, both purely physical and technical. character. The already mentioned problem of the stability of a hot plasma placed in a magnetic field belongs to the former. trap. The use of strong magnets special fields configuration allowed to suppress many. types of macroscopic instabilities, but will end. the issue is still not resolved.

In particular, for an interesting and important system - the tokamak - the so-called. the problem of "big disruption", in which the plasma current cord is first drawn to the axis of the chamber, then interrupted for several. ms and a lot of energy is discharged onto the chamber walls. In addition to thermal shock, the chamber also experiences mechanical shock. .

A serious difficulty is also the formation of beams of fast electrons detached from the main. ensemble of plasma electrons. These beams lead to a strong increase in heat and particle fluxes across the field. In ultrafast systems, the formation of a group of fast electrons in the plasma corona surrounding the target is also observed. These electrons have time to prematurely heat the central zones of the target, preventing the achievement of the required degree of compression and the subsequent programmed occurrence of nuclear reactions. Main The difficulty in these systems is the implementation of stable spherically symmetric compression of targets.

Another difficulty is related to the problem of impurities. El.-mag. at the values ​​used P And T plasma and possible sizes reactor freely leaves the plasma, but for a purely hydrogen plasma, these energetic. losses determined in the main. bremsstrahlung electrons, in the case of (d, 1)-reactions, they are overlapped by nuclear energy release already at temp-pax above 4-10 7 K. However, even a small addition of foreign atoms with large Z, which at the considered temp-pax are in a strongly ionized state, lead to an increase in energy. losses are above the acceptable level. Extraordinary efforts are required (continuous improvement of vacuum installations, the use of refractory and difficult-to-disperse substances, such as tungsten, as a diaphragm material, the use of devices for trapping impurity atoms, etc.) to keep the content of impurities in the plasma below the permissible level (=<0,1%). Для инер-циальных систем-предотвращение перемешивания вещества сжимающей оболочки с термоядерным топливом на конечных стадиях сжатия.

On fig. 3 shows the parameters achieved at decomp. installations by 1994. As can be seen, the parameters of these systems are close to the threshold values. Moreover, on the largest operating tokamak JET (West Europe) in November 1991, a discharge on (d, 1)-plasma with a duration of approx. 2 s. In this case, the fusion energy was obtained under controlled conditions at a power level of ~ 1 MW. A year later, ~6 MW energy was obtained at the TFTR facility. From ecological For reasons of consideration, the experiments were carried out not on an equal-component mixture of deuterium and tritium, but with a tritium content of 10-11%. In the TFTR experiment, the ratio of fusion energy to cost. energy was 0.15 (in terms of an equal-component mixture ~0.46). The success of these experiments has clearly put forward a leading position among the installations being developed under the UTS program. In connection with the foregoing, it is clear that in the international ITER project, which is supposed to be implemented by 2003 and which should serve as an experiment. model of a future power plant with a fusion reactor, it is proposed to use the tokamak system.

Rice. 3. Parameters achieved at various facilities for studying the problem of controlled thermonuclear fusion by 1991. T-10 tokamak facility of the IV Kurchatov Institute of Atomic Energy (USSR); PLT tokamak facility at Princeton Laboratory (USA); Alkator - tokamak installation of the Massachusetts Institute of Technology (USA); TFR - tokamak plant in Fontenay-aux-Rose (France); 2 HPV - open trap of the Livermore Laboratory (USA); "Shiva" (Livermore Laboratory, USA); "Downpour" (FIAN, Moscow); stellarator "Wendelstein UP" (Garching, Germany).

However, it should be clearly understood that the path from a working reactor to an operating power plant is still very long. Radiation the activation of the walls of the reactor chamber when operating on fuel containing tritium is extremely high. Even if it is possible to carry out stationary operation of the reactor for a period of time, mechanical. resistance of the first wall of the chamber as a result of radiation. damage is unlikely to exceed (according to experts) 5-6 years. This means the need for periodic complete dismantling of the installation and subsequent reassembly with the help of remotely operating robots, since the residual will be measured in thousands of megacuries. Deep underground burial of huge parts of the installation will also be inevitable.

A beautiful possibility of a sharp reduction in the radioactivity of the operating system and the residual induced activity can be achieved when operating on fuel with the isotope 3 He. According to the reaction, the energy release remains at the same level, the formation of neutrons will occur only due to side (d, d) reactions. Unfortunately, the necessary isotope 3 would not have to be brought from the surface of the Moon, where it is present in concentrations, while on Earth its content is negligible.

If we talk about long-term forecasts, then the optimum should probably be sought in a combination of solar energy and CTS. For the possibilities associated with exceptionally interesting, but even more distant prospects for using the process of muon catalysis for the implementation of CTS, see Art. Muont catalysis.

Lit.: Artsimovich L. A., Managed, 2nd ed., M., 1963; Furth, H. P., Tokamak research, "Nucl. Fus.", 1975, v. 15, no. 3, p. 487; Lukyanov. Yu., Hot Plasma and Controlled Nuclear Fusion, Moscow, 1975; Problems of laser thermonuclear fusion. Sat. Art., M., 1976; Results of science and technology, ser. Plasma Physics, vol. 1-3, Moscow, 1980-82. WITH. Y. Lukyanov.

Physical encyclopedia. In 5 volumes. - M.: Soviet Encyclopedia. Editor-in-Chief A. M. Prokhorov. 1988 .

See what "CONTROLLED FUSION" is in other dictionaries:

- (UTS), the process of fusion of light atomic nuclei, taking place with the release of energy, at high temperatures under controlled, controlled conditions. TTS has not yet been implemented. To carry out fusion reactions, the reacting nuclei must be brought together by ... ... Physical Encyclopedia

- (UTS), the fusion of light atomic nuclei (for example, deuterium and tritium) with the release of energy, occurring at very high temperatures (? 108K) under controlled conditions (in a thermonuclear reactor). The possibility of implementing the TCB is theoretically calculated in ... ... Modern Encyclopedia

- (UTS) the scientific problem of the implementation of the synthesis of light nuclei in order to produce energy. The solution to the problem will be achieved in plasma at a temperature of T 108K and fulfillment of the Lawson criterion (n? 1014 cm 3.s, where n is the density of high-temperature plasma; ?… … Big Encyclopedic Dictionary

controlled thermonuclear fusion- - [A.S. Goldberg. English Russian Energy Dictionary. 2006] Energy topics in general EN controlled thermonuclear fusioncontrolled nuclear fusionCTF … Technical Translator's Handbook

Controlled thermonuclear fusion- (UTS), the fusion of light atomic nuclei (for example, deuterium and tritium) with the release of energy, occurring at very high temperatures (³108K) under controlled conditions (in a thermonuclear reactor). The possibility of implementing the TCB is theoretically calculated in ... ... Illustrated Encyclopedic Dictionary

The sun is a natural thermonuclear reactor Controlled thermonuclear fusion (CTF) is the synthesis of heavier atomic nuclei from lighter ones in order to obtain energy, which, unlike explosive thermonuclear fusion (and ... Wikipedia

The process of fusion of light atomic nuclei, which occurs with the release of energy at high temperatures under controlled, controlled conditions. The rates of thermonuclear reactions are low due to the Coulomb repulsion (see Coulomb law) ... ... Great Soviet Encyclopedia

Controlled thermonuclear fusion- controlled flow of fusion of light nuclei (deuterium, tritium nuclei) into helium nuclei for the purpose of energy production (uncontrolled synthesis is carried out in a hydrogen bomb). There is no technical solution yet... Beginnings of modern natural science, Rozhansky V.A. The textbook contains a presentation of the issues of kinetics, dynamics and equilibrium of plasma, as well as transfer processes in it. This course differs from most courses on plasma physics in that…

Cold can also be called cold fusion. Its essence lies in the possibility of realizing a nuclear fusion reaction occurring in any chemical systems. This assumes that there is no significant overheating of the working substance. As you know, when they are usually carried out, they create a temperature that can be measured in millions of degrees Kelvin. Cold fusion in theory does not require such a high temperature.

Numerous studies and experiments

Cold fusion research is, on the one hand, considered pure fraud. No other scientific direction can be compared with him in this. On the other hand, it is possible that this area of ​​science has not been fully studied, and cannot be considered a utopia at all, much less a fraud. However, in the history of the development of cold fusion, there were still, if not deceivers, then certainly crazy ones.

The recognition of this direction as pseudoscience and the reason for the criticism that the technology of cold nuclear fusion was subjected to were the numerous failures of scientists working in this area, as well as falsifications made by individuals. Since 2002, most scientists believe that work on solving this issue is futile.

At the same time, some attempts to carry out such a reaction are still ongoing. So, in 2008, a Japanese scientist from Osaka University publicly demonstrated an experiment performed with an electrochemical cell. It was Yoshiaki Arata. After such a demonstration, the scientific community again began to talk about the possibility or impossibility of cold fusion, which nuclear physics can provide. Individual scientists qualified in nuclear physics and chemistry are looking for justifications for this phenomenon. Moreover, they do this in order to find not a nuclear explanation for it, but another, alternative one. In addition, this is also due to the fact that there is no information about neutron radiation.

The story of Fleischman and Pons

The very history of the promulgation of this type of scientific direction in the eyes of the world community is suspicious. It all started on March 23, 1989. It was then that Professor Martin Fleishman and his partner Stanley Pons held a press conference, which was held at the university where the chemists worked, in Utah (USA). Then they declared that they had carried out a cold nuclear fusion reaction by simply passing an electric current through an electrolyte. According to chemists, as a result of the reaction, they were able to obtain a positive energy output, that is, heat. In addition, they observed nuclear radiation resulting from the reaction and coming from the electrolyte.

The statement made literally made a splash in the scientific community. Of course, low-temperature nuclear fusion, produced on a simple desk, could radically change the whole world. Complexes of huge chemical installations are no longer needed, which also cost a huge amount of money, and the result in the form of obtaining the desired reaction when it comes is unknown. If everything were confirmed, Fleishman and Pons would have an amazing future, and humanity - a considerable reduction in costs.

However, the statement made in this way by chemists was their mistake. And, who knows, perhaps the most important. The fact is that in the scientific community it is not customary to make any statements to the media about their inventions or discoveries before information about them is published in special scientific journals. Scientists who do this are instantly criticized, it is considered a kind of bad form in the scientific community. According to the rules, a researcher who has made a discovery is implicitly obliged to first notify the scientific community about this, which will decide whether this invention is really true, whether it is worth recognizing it as a discovery at all. From a legal point of view, this is considered an obligation to completely preserve the secrecy about what happened, which the discoverer must observe from the moment of submitting his article to the publication and until the moment of its publication. Nuclear physics is no exception in this respect.

Fleishman and his colleague submitted such an article to a scientific journal called Nature, which was the most authoritative scientific publication on a global scale. All people associated with science know that such a journal will not publish unverified information, and even more so will not print just anyone. Martin Fleishman was already at that time considered a fairly respected scientist working in the field of electrochemistry, so the submitted article was supposed to be published soon. And so it happened. Three months after the ill-fated conference, the publication was published, but the excitement around the opening was already in full swing. Perhaps that is why the editor-in-chief of Nature, John Maddox, already in the next monthly issue of the journal published his doubts about the discovery made by Fleishman and Pons and the fact that they had obtained the energy of a nuclear reaction. In his note, he wrote that chemists should be punished for its premature publication. In the same place, they were told that real scientists would never allow their inventions to be made public, and persons who do so can be considered mere adventurers.

Some time later, Pons and Fleishman received another blow that can be called crushing. A number of researchers from the American scientific institutions of the United States (Massachusetts and California Institute of Technology) conducted, that is, repeated the experiment of chemists, creating the same conditions and factors. However, this did not lead to the result declared by Fleishman.

Possible or impossible?

Since that time, there has been a clear division of the entire scientific community into two camps. Supporters of one convinced everyone that a cold fusion is a fiction that is not based on anything. Others, on the contrary, are still convinced that cold nuclear fusion is possible, that the ill-fated chemists nevertheless made a discovery that in the end can save all of humanity, giving it an inexhaustible source of energy.

The fact that if, nevertheless, a new method is invented, with the help of which cold nuclear fusion reactions will be possible, and, accordingly, the significance of such a discovery will be invaluable for all people on a global scale, attracts more and more new scientists to this scientific direction, partly of which may actually be considered fraudulent. Entire states are making significant efforts to build just one thermonuclear station, while spending huge amounts of money, and cold fusion is able to extract energy in absolutely simple and fairly inexpensive ways. This is what attracts those who want to profit fraudulently, as well as other people with mental disorders. Among the adherents of this method of obtaining energy, you can find both.

The story with a cold fusion was simply bound to fall into the archive of so-called pseudoscientific stories. If you look at the method by which the energy of nuclear fusion is obtained with a sober look, you can understand that it takes a huge amount of energy to combine two atoms into one. It is necessary to overcome electrical resistance. In the building under construction this moment International, which will be located in the city of Caradache in France, it is planned to combine two atoms, which are the lightest of those existing in nature. As a result of such a connection, a positive energy release is expected. These two atoms are tritium and deuterium. They are isotopes of hydrogen, so nuclear fusion of hydrogen would be the basis. To make such a connection, an unthinkable temperature is needed - hundreds of millions of degrees. Of course, this will require a lot of pressure. For this reason, many scientists believe that cold controlled nuclear fusion is impossible.

Successes and failures

However, in order to justify this synthesis under consideration, it should be noted that among his admirers there are not only people with delusional ideas and scammers, but also quite normal specialists. After the performance of Fleischman and Pons and the failure of their discovery, many scientists and scientific institutions continued to pursue this direction. Not without Russian specialists, who also made corresponding attempts. And the most interesting thing is that such experiments in some cases ended in success, and in others - in failure.

However, everything is strict in science: if a discovery has occurred, and the experiment has been successful, then it must be repeated again with a positive result. If this is not so, such a discovery will not be recognized by anyone. Moreover, the repetition of a successful experiment could not be done by the researchers themselves. In some cases they succeeded, in others they did not. Because of what this happens, no one could explain, there is still no scientifically based reason for such inconstancy.

A real inventor and genius

The whole story with Fleishman and Pons described above has the other side of the coin, or rather, the truth carefully hidden by Western countries. The fact is that Stanley Pons was previously a citizen of the USSR. In 1970, he was a member of the expert team developing thermionic installations. Of course, Pons was privy to many secrets of the Soviet state and, having emigrated to the United States, tried to realize them.

The true discoverer, who achieved some success in cold nuclear fusion, was Ivan Stepanovich Filimonenko.

I. S. Filimonenko died in 2013. He was a scientist who almost stopped the entire development of nuclear energy, not only in his country, but throughout the world. It was he who almost created the installation of nuclear cold fusion, which, in contrast, would be safer and very cheap. In addition to the specified installation, the Soviet scientist created an aircraft based on the principle of antigravity. He was known as a whistleblower of the hidden dangers that nuclear energy can bring to mankind. The scientist worked in the defense complex of the USSR, was an academician and an expert on it. It is noteworthy that some of the works of the academician, including Filimonenko's cold nuclear fusion, are still classified. Ivan Stepanovich was a direct participant in the creation of hydrogen, nuclear and neutron bombs, was engaged in the development of nuclear reactors designed to launch rockets into space.

In 1957, Ivan Filimonenko developed a cold nuclear fusion power plant, with the help of which the country could save up to three hundred billion dollars a year by using it in the energy sector. This invention of the scientist was initially fully supported by the state, as well as by such well-known researchers as Kurchatov, Keldysh, Korolev. Further development and bringing the invention of Filimonenko to the finished state was authorized at that time by Marshal Zhukov himself. The discovery of Ivan Stepanovich was a source from which clean nuclear energy was to be extracted, and besides, with its help it would be possible to obtain protection from nuclear radiation and eliminate the consequences of radioactive contamination.

Removal of Filimonenko from work

It is possible that after some time the invention of Ivan Filimonenko would be produced on an industrial scale, and humanity would get rid of many problems. However, fate, in the person of some people, decreed otherwise. His colleagues Kurchatov and Korolev died, and Marshal Zhukov retired. This was the beginning of the so-called undercover game in scientific circles. The result was the cessation of all Filimonenko's work, and in 1967 he was fired. An additional reason for such treatment of the honored scientist was his struggle to stop nuclear weapons testing. With his work, he constantly proved the harm done to both nature and directly to people; at his suggestion, many projects to launch rockets with nuclear reactors into space were stopped (any accident on such a rocket that occurred in orbit could threaten radioactive contamination of the entire Earth). Given the arms race that was gaining momentum at that time, Academician Filimonenko became objectionable to some high-ranking officials. His experimental facilities are recognized as contrary to the laws of nature, the scientist himself is fired, expelled from the Communist Party, deprived of all titles and generally declared a mentally deranged person.

Already in the late eighties - early nineties, the work of the academician was resumed, new experimental facilities were developed, but all of them were not brought to a positive result. Ivan Filimonenko proposed the idea of ​​using his mobile unit to eliminate the consequences in Chernobyl, but it was rejected. In the period from 1968 to 1989, Filimonenko was removed from any tests and work in the direction of cold fusion, and the developments themselves, diagrams and drawings, along with some Soviet scientists, went abroad.

In the early 1990s, the United States announced successful tests in which they allegedly obtained nuclear energy as a result of cold fusion. This was the impetus for the fact that the legendary Soviet scientist was again remembered by his state. He was reinstated, but that didn't help either. By that time, the collapse of the USSR began, funding was limited, and accordingly, there were no results. As Ivan Stepanovich later said in an interview, seeing the ongoing and at the same time unsuccessful attempts by many scientists from all over the world to obtain positive results from cold nuclear fusion, he realized that without him no one would be able to complete the job. And, indeed, he spoke the truth. From 1991 to 1993, American scientists who got the Filimonenko installation could not understand the principle of its operation, and a year later they completely dismantled it. In 1996, influential people from the United States offered Ivan Stepanovich one hundred million dollars just to provide them with advice, explaining how a cold fusion reactor works, to which he refused.

Ivan Filimonenko, through experiments, established that as a result of the decomposition of the so-called heavy water by electrolysis, it decomposes into oxygen and deuterium. The latter, in turn, dissolves in the palladium of the cathode, in which nuclear fusion reactions develop. In the process of what is happening, Filimonenko recorded the absence of both radioactive waste and neutron radiation. In addition, as a result of his experiments, Ivan Stepanovich found that his nuclear fusion reactor emits indefinite radiation, and it is this radiation that greatly reduces the half-life of radioactive isotopes. That is, radioactive contamination is neutralized.

There is an opinion that Filimonenko at one time refused to replace nuclear reactors with his installation in underground shelters prepared for the top leaders of the USSR in case of a nuclear war. At that time, the Caribbean crisis was raging, and therefore the possibility of its beginning was very high. The ruling circles of both the USA and the USSR were stopped only by the fact that in such underground cities, pollution from nuclear reactors would still kill all living things a few months later. The Filimonenko cold fusion reactor involved could create a safety zone from radioactive contamination, therefore, if the academician agreed to this, then the likelihood of a nuclear war could be increased several times. If this was indeed the case, then depriving him of all awards and further repressions find their logical justification.

Warm nuclear fusion

I. S. Filimonenko created a thermionic hydrolysis power plant, which was absolutely environmentally friendly. To date, no one has been able to create a similar analogue of TEGEU. The essence of this installation and at the same time the difference from other similar units was that it did not use nuclear reactors, but installations of nuclear fusion occurring at an average temperature of 1150 degrees. Therefore, such an invention was called the installation of warm nuclear fusion. At the end of the eighties, under the capital, in the city of Podolsk, 3 such installations were created. The Soviet academician Filimonenko was directly involved in this, directing the entire process. The power of each TEGPP was 12.5 kW, heavy water was used as the main fuel. Just one kilogram of it, during the reaction, released energy equivalent to that which can be obtained by burning two million kilograms of gasoline! This alone speaks of the volume and significance of the inventions of the great scientist, that the cold nuclear fusion reactions he developed could bring the desired result.

Thus, at present it is not known for certain whether a cold fusion has the right to exist or not. It is quite possible that if it were not for the repressions against the real genius of science Filimonenko, then the world would not be the same now, and the life expectancy of people could increase many times over. After all, even then Ivan Filimonenko stated that radioactive radiation is the cause of people's aging and imminent death. It is the radiation that is now literally everywhere, not to mention megacities, that breaks human chromosomes. Perhaps that is why the biblical characters lived for a thousand years, since at that time this destructive radiation probably did not exist.

The installation created by Academician Filimonenko in the future could save the planet from such killing pollution, in addition, providing an inexhaustible source of cheap energy. Like it or not, time will tell, but it is a pity that this time could already come.

Shikanov A.S. // Soros Educational Journal, No. 8, 1997, pp: 86-91

We will look at the physical principles of laser fusion, a rapidly developing scientific field based on two outstanding discoveries of the 20th century: thermonuclear reactions and lasers.

Thermonuclear reactions proceed during the fusion (synthesis) of the nuclei of light elements. In this case, along with the formation of heavier elements, excess energy is released in the form of the kinetic energy of the final reaction products and gamma radiation. The large energy release during the course of thermonuclear reactions attracts the attention of scientists because of the possibility of their practical application in terrestrial conditions. Thus, thermonuclear reactions on a large scale were carried out in a hydrogen (or thermonuclear) bomb.

Extremely attractive is the possibility of utilizing the energy released during thermonuclear reactions to solve the energy problem. The fact is that the fuel for this method of obtaining energy is the hydrogen isotope deuterium (D), the reserves of which in the oceans are practically inexhaustible.

Fusion Reactions and Controlled Fusion

A thermonuclear reaction is the process of fusion (or fusion) of light nuclei into heavier ones. Since in this case the formation of strongly bound nuclei from looser ones occurs, the process is accompanied by the release of binding energy. The easiest way is the fusion of hydrogen isotopes - deuterium D and tritium T. The deuterium nucleus - deuteron contains one proton and one neutron. Deuterium is found in water at a ratio of one part to 6500 parts of hydrogen. The nucleus of tritium, the triton, consists of a proton and two neutrons. Tritium is unstable (half-life 12.4 years), but can be obtained as a result of nuclear reactions.

During the fusion of deuterium and tritium nuclei, helium He is formed with atomic mass equal to four, and the neutron n. As a result of the reaction, an energy of 17.6 MeV is released.

The fusion of deuterium nuclei occurs along two channels with approximately the same probability: in the first one, tritium and a proton p are formed and an energy equal to 4 MeV is released; in the second channel - helium with an atomic mass of 3 and a neutron, and the released energy is 3.25 MeV. These reactions are presented in the form of formulas

D + T = 4He + n + 17.6 MeV,

D + D = T + p + 4.0 MeV,

D + D = 3He + n + 3.25 MeV.

Before the fusion process, the deuterium and tritium nuclei have an energy of the order of 10 keV; the energy of the reaction products reaches values ​​on the order of units and tens of megaelectronvolts. It should also be noted that the cross section of the D + T reaction and the rate of its occurrence are much higher (hundreds of times) than for the D + D reaction. Therefore, it is much easier for the D + T reaction to achieve conditions when the released thermonuclear energy exceeds the costs of organizing processes mergers.

Synthesis reactions involving other nuclei of elements (for example, lithium, boron, etc.) are also possible. However, the reaction cross sections and their rates for these elements are much smaller than for hydrogen isotopes, and reach appreciable values ​​only for temperatures of the order of 100 keV. Achieving such temperatures in thermonuclear installations is currently completely unrealistic, so only fusion reactions of hydrogen isotopes can be of practical use in the near future.

How can a thermonuclear reaction be carried out? The problem is that the fusion of the nuclei is prevented by the electric forces of repulsion. In accordance with the Coulomb law, the electric repulsion force grows inversely proportional to the square of the distance between the interacting nuclei F ~ 1/ r 2. Therefore, for the fusion of nuclei, the formation of new elements and the release of excess energy, it is necessary to overcome the Coulomb barrier, that is, to perform work against the repulsion forces, informing the nuclei the necessary energy.

There are two possibilities. One of them consists in the collision of two beams of light atoms accelerated towards each other. However, this approach turned out to be inefficient. The fact is that the probability of nuclear fusion in accelerated beams is extremely small due to the low density of nuclei and the negligible time of their interaction, although the creation of beams of the required energy in existing accelerators is not a problem.

Another way, on which modern researchers have stopped, is heating the substance to high temperatures (about 100 million degrees). The higher the temperature, the higher the average kinetic energy of the particles and the greater their number can overcome the Coulomb barrier.

To quantify the efficiency of thermonuclear reactions, the energy gain factor Q is introduced, which is equal to

where Eout is the energy released as a result of fusion reactions, Eset is the energy used to heat the plasma to thermonuclear temperatures.

In order for the energy released as a result of the reaction to be equal to the energy costs for heating the plasma to temperatures of the order of 10 keV, the so-called Lawson criterion must be satisfied:

(Nt) $ 1014 s/cm3 for D-T reaction,

(Nt) $ 1015 s/cm3 for D-D reaction.

Here N is the density of the deuterium-tritium mixture (the number of particles in a cubic centimeter), t is the time of effective fusion reactions.

To date, two largely independent approaches to solving the problem of controlled thermonuclear fusion have been formed. The first of them is based on the possibility of confining and thermally insulating a high-temperature plasma of relatively low density (N © 1014-1015 cm-3) by a magnetic field of a special configuration for a relatively long time (t © 1-10 s). Such systems include "Tokamak" (short for "toroidal chamber with magnetic coils"), proposed in the 50s in the USSR.

The other way is impulse. In the pulsed approach, it is necessary to quickly heat and compress small portions of matter to such temperatures and densities at which thermonuclear reactions would have time to efficiently proceed during the existence of an uncontained or, as they say, inertially confined plasma. Estimates show that in order to compress matter to densities of 100-1000 g/cm3 and heat it to a temperature T © 5-10 keV, it is necessary to create pressure on the surface of the spherical target P © 5 » 109 atm, that is, a source is needed that would allow energy to be delivered to the target surface with a power density q © 1015 W/cm2.

PHYSICAL PRINCIPLES OF LASER FUSION

The idea of ​​using high-power laser radiation for heating dense plasma to thermonuclear temperatures was first proposed by N.G. Basov and O.N. Krokhin in the early 1960s. To date, an independent area of ​​thermonuclear research has been formed - laser thermonuclear fusion (LTF).

Let us dwell briefly on the basic physical principles underlying the concept of achieving high degrees of compression of substances and obtaining high energy gains with the help of laser microexplosions. Consideration will be built on the example of the so-called direct compression mode. In this mode, a microsphere (Fig. 1) filled with thermonuclear fuel is “uniformly” irradiated from all sides by a multichannel laser. As a result of the interaction of heating radiation with the target surface, a hot plasma with a temperature of several kiloelectronvolts (the so-called plasma corona) is formed, which expands towards the laser beam with characteristic velocities of 107–108 cm/s.

Without being able to dwell on absorption processes in the plasma corona in more detail, we note that in modern model experiments at laser radiation energies of 10–100 kJ for targets comparable in size to targets for high gains, it is possible to achieve high (© 90%) coefficients of absorption of heating radiation.

As we have already seen, light radiation cannot penetrate into the dense layers of the target (the density of a solid is 1023 cm-3). Due to thermal conductivity, the energy absorbed in plasma with an electron density lower than ncr is transferred to denser layers, where the target substance is ablated. The remaining unevaporated layers of the target accelerate towards the center under the action of thermal and jet pressure, compressing and heating the fuel contained in it (Fig. 2). As a result, the laser radiation energy is converted at the stage under consideration into the kinetic energy of the matter flying towards the center and into the energy of the expanding corona. It is obvious that the useful energy is concentrated in the movement towards the center. The efficiency of the contribution of light energy to the target is characterized by the ratio of the indicated energy to the total radiation energy, the so-called hydrodynamic efficiency factor (COP). Achieving a sufficiently high hydrodynamic efficiency (10-20%) is one of the important problems of laser thermonuclear fusion.

Rice. 2. Radial distribution of the temperature and density of matter in the target at the stage of shell acceleration to the center

What processes can hinder the achievement of high compression ratios? One of them is that at thermonuclear radiation densities q > 1014 W/cm2, a significant fraction of the absorbed energy is transformed not into a classical electron heat conduction wave, but into fast electron flows, the energy of which is much higher than the plasma corona temperature (the so-called epithermal electrons). This can occur both due to resonant absorption and due to parametric effects in the plasma corona. In this case, the path length of epithermal electrons may turn out to be comparable with the dimensions of the target, which will lead to preliminary heating of the compressible fuel and the impossibility of obtaining limiting compressions. X-ray quanta of high energy (hard X-ray radiation), accompanying epithermal electrons, also have a large penetrating power.

trend experimental studies recent years is the transition to the use of short-wavelength laser radiation (l< 0,5 мкм) при умеренных плотностях потока (q < 1015 Вт/см2). Практическая возможность перехода к нагреву плазмы коротковолновым излучением связана с тем, что коэффициенты конверсии излучения твердотельного неодимого лазера (основного кандидата в драйверы для лазерного термоядерного синтеза) с длиной волны l = 1,06 мкм в излучения второй, третьей и четвертой гармоник с помощью нелинейных кристаллов достигает 70-80%. В настоящее время фактически все крупные лазерные установки на неодимовом стекле снабжены системами умножения частоты. Физической причиной преимущества использования коротковолнового излучения для нагрева и сжатия микросфер является то, что с уменьшением длины волны увеличивается поглощение в плазменной короне и возрастают абляционное давление и гидродинамический коэффициент передачи. На несколько порядков уменьшается доля надтепловых электронов, генерируемых в плазменной короне, что является чрезвычайно выгодным для режимов как прямого, так и непрямого сжатия. Для непрямого сжатия принципиально и то, что с уменьшением длины волны увеличивается конверсия поглощенной плазмой энергии в мягкое рентгеновское излучение. Остановимся теперь на режиме непрямого сжатия. Физический анализ показывает, что осуществление режима сжатия до высоких плотностей топлива оптимально для простых и сложных оболочечных мишеней с аспектным отношением R / DR в несколько десятков. Здесь R — радиус оболочки, DR — ее толщина. Однако сильное сжатие может быть ограничено развитием гидродинамических неустойчивостей, которые проявляются в отклонении движения оболочки на стадиях ее ускорения и торможения в центре от сферической симметрии и зависят от отклонений initial form target from a perfectly spherical, inhomogeneous distribution of incident laser beams over its surface. The development of instability as the shell moves toward the center leads first to a deviation of the motion from spherically symmetric, then to flow turbulence, and finally to mixing of the target layers and the deuterium-tritium fuel. As a result, a formation may appear in the final state, the shape of which differs sharply from the spherical core, and the average density and temperature are much lower than the values ​​corresponding to one-dimensional compression. In this case, the initial structure of the target (for example, a certain set of layers) can be completely destroyed. physical nature this type of instability is equivalent to the instability of a layer of mercury located on the water surface in the gravitational field. In this case, as is known, there is a complete mixing of mercury and water, that is, in the final state, mercury will be at the bottom. A similar situation can occur during accelerated movement of a target with a complex structure towards the center of the substance, or in general case in the presence of density and pressure gradients. The requirements for the quality of targets are quite strict. Thus, the inhomogeneity of the microsphere wall thickness should not exceed 1%, the uniformity of the energy absorption distribution over the target surface should not exceed 0.5%. The proposal to use the scheme of indirect compression is just related to the possibility of solving the problem of stability of target compression. The schematic diagram of the experiment in the indirect compression mode is shown in fig. 3. Laser radiation is introduced into the cavity (hohlraum), focusing on the inner surface of the outer shell, consisting of a substance with a high atomic number, such as gold. As already noted, up to 80% of the absorbed energy is transformed into soft X-ray radiation, which heats and compresses the inner shell. The advantages of such a scheme include the possibility of achieving a higher uniformity of the absorbed energy distribution over the target surface, simplification of the laser scheme and focusing conditions, etc. However, there are also disadvantages associated with the loss of energy for conversion into X-rays and the complexity of introducing radiation into the cavity. What is the current state of research on laser fusion? Experiments to achieve high densities of compressible fuel in the direct compression regime began in the mid-1970s at the V.I. P.N. Lebedev, where the density of compressible deuterium © 10 g/cm3 was achieved on the Kalmar facility with energy E = 200 J. Subsequently, work programs on LTS were actively developed in the USA (Shiva and Nova facilities at the Livermore National Laboratory, Omega at the University of Rochester), Japan (Gekko-12), Russia (Dolphin at FIAN, Iskra-4", "Iskra-5" in Arzamas-16) at the laser energy level of 1-100 kJ. All aspects of heating and compression of targets of various configurations in direct and indirect compression modes are studied in detail. An ablation pressure of ~100 Mbar and a microsphere collapse velocity of V > 200 km/s are achieved at hydrodynamic efficiency values ​​of about 10%. Progress in the development of laser systems and target structures has made it possible to ensure a degree of uniformity of irradiation of a compressible shell of 1–2% both under direct and indirect compression. In both regimes, compressed gas densities of 20–40 g/cm3 were achieved, and the compressed shell density of 600 g/cm3 was recorded at the Gekko-12 facility. Maximum neutron yield N = 1014 neutrons per burst.

CONCLUSION

Thus, the entire set of received experimental results and their analysis point to the practical feasibility of the next stage in the development of laser thermonuclear fusion—the achievement of deuterium-tritium gas densities of 200–300 g/cm And ).

At present, the element base is being intensively developed and projects are being created for megajoule-level laser installations. At the Livermore Laboratory, the creation of an installation on neodymium glass with an energy of E = 1.8 MJ has begun. The cost of the project is $2 billion. The creation of an installation of a similar level is planned in France. It is planned to achieve an energy gain Q ~ 100 at this facility. It must be said that the launch of facilities of this scale will not only bring the possibility of creating a thermonuclear reactor based on laser fusion, but will also provide researchers with a unique physical object - a microexplosion with energy release 107-109 J, a powerful source of neutron, neutrino, x-ray and g-radiation. This will not only be of great general physical importance (the ability to study substances in extreme states, the physics of combustion, the equation of state, laser effects, etc.), but will also make it possible to solve special problems of an applied, including military, nature.

For a reactor based on laser fusion, however, it is necessary to create a megajoule-level laser operating at a repetition rate of several hertz. A number of laboratories are investigating the possibility of creating such systems based on new crystals. Starting up an experimental reactor American program planned for 2025.

Scientists at the Princeton Plasma Physics Laboratory have proposed the idea of ​​the most durable nuclear fusion device that can operate for more than 60 years. At the moment, this is a daunting task: scientists are struggling to get a fusion reactor to work for a few minutes - and then years. Despite the complexity, the construction of a fusion reactor is one of the most promising tasks of science, which can bring great benefits. We tell you what you need to know about thermonuclear fusion.

1. What is thermonuclear fusion?

Do not be afraid of this cumbersome phrase, in fact, everything is quite simple. Thermonuclear fusion is a type of nuclear reaction.

During a nuclear reaction, the nucleus of an atom interacts either with an elementary particle or with the nucleus of another atom, due to which the composition and structure of the nucleus change. A heavy atomic nucleus can decay into two or three lighter ones - this is a fission reaction. There is also a fusion reaction: this is when two light atomic nuclei merge into one heavy one.

Unlike nuclear fission, which can take place both spontaneously and forcedly, nuclear fusion is impossible without the supply of external energy. As you know, opposites attract, but atomic nuclei are positively charged - so they repel each other. This situation is called the Coulomb barrier. To overcome repulsion, it is necessary to disperse these particles to crazy speeds. This can be done at very high temperatures, on the order of several million kelvins. It is these reactions that are called thermonuclear.

2. Why do we need thermonuclear fusion?

During nuclear and thermonuclear reactions, a huge amount of energy is released, which can be used for various purposes - you can create most powerful weapon, or you can convert nuclear energy into electricity and supply it to the whole world. Nuclear decay energy has long been used in nuclear power plants. But thermonuclear energy looks more promising. In a thermonuclear reaction, for each nucleon (the so-called constituent nuclei, protons and neutrons), much more energy is released than in a nuclear reaction. For example, when fission of a uranium nucleus per nucleon accounts for 0.9 MeV (megaelectronvolt), and whenIn the synthesis of a helium nucleus, an energy equal to 6 MeV is released from hydrogen nuclei. Therefore, scientists are learning to carry out thermonuclear reactions.

Fusion research and the construction of reactors allow the expansion of high-tech production, which is useful in other areas of science and high-tech.

3. What are thermonuclear reactions?

Thermonuclear reactions are divided into self-sustaining, uncontrolled (used in hydrogen bombs) and controlled (suitable for peaceful purposes).

Self-sustaining reactions take place in the interiors of stars. However, there are no conditions on Earth for such reactions to take place.

People have been conducting uncontrolled or explosive thermonuclear fusion for a long time. In 1952, during Operation Evie Mike, the Americans detonated the world's first thermonuclear explosive device, which had no practical value as a weapon. And in October 1961, the world's first thermonuclear (hydrogen) bomb (Tsar Bomba, Kuzkin's Mother), developed by Soviet scientists under the leadership of Igor Kurchatov, was tested. It was the most powerful explosive device in the history of mankind: the total energy of the explosion, according to various sources, ranged from 57 to 58.6 megatons of TNT. In order to detonate a hydrogen bomb, it is first necessary to obtain a high temperature during a conventional nuclear explosion - only then will the atomic nuclei begin to react.

The power of the explosion in an uncontrolled nuclear reaction is very high, in addition, the proportion of radioactive contamination is high. Therefore, in order to use thermonuclear energy for peaceful purposes, it is necessary to learn how to manage it.

4. What is needed for a controlled thermonuclear reaction?

Hold the plasma!

Unclear? Now let's explain.

First, atomic nuclei. IN nuclear power isotopes are used - atoms that differ from each other in the number of neutrons and, accordingly, in atomic mass. The hydrogen isotope deuterium (D) is extracted from water. Superheavy hydrogen or tritium (T) is a radioactive isotope of hydrogen that is a by-product of decay reactions carried out in conventional nuclear reactors. Also in thermonuclear reactions, a light isotope of hydrogen, protium, is used: this is the only stable element that does not have neutrons in the nucleus. Helium-3 is contained on Earth in negligible amounts, but it is very abundant in the lunar soil (regolith): in the 80s, NASA developed a plan for hypothetical installations for processing regolith and isotope extraction. On the other hand, another isotope, boron-11, is widespread on our planet. 80% of the boron on Earth is an isotope necessary for nuclear scientists.

Secondly, very heat. The substance participating in a thermonuclear reaction must be an almost completely ionized plasma - it is a gas in which free electrons and ions of various charges float separately. To turn a substance into a plasma, a temperature of 10 7 -10 8 K is required - these are hundreds of millions of degrees Celsius! Such ultra-high temperatures can be obtained by creating high-power electric discharges in the plasma.

However, simply heat the necessary chemical elements it is forbidden. Any reactor will instantly vaporize at these temperatures. A completely different approach is required here. To date, it is possible to keep the plasma in a limited area with the help of heavy-duty electric magnets. But it has not yet been possible to fully use the energy obtained as a result of a thermonuclear reaction: even under the influence of a magnetic field, the plasma spreads in space.

5. What reactions are most promising?

The main nuclear reactions planned to be used for controlled fusion will use deuterium (2H) and tritium (3H), and in the longer term helium-3 (3He) and boron-11 (11B).

Here are the most interesting reactions.

1) 2 D+ 3 T -> 4 He (3.5 MeV) + n (14.1 MeV) - deuterium-tritium reaction.

2) 2 D+ 2 D -> 3 T (1.01 MeV) + p (3.02 MeV) 50%

2 D+ 2 D -> 3 He (0.82 MeV) + n (2.45 MeV) 50% is the so-called deuterium monopropellant.

Reactions 1 and 2 are fraught with neutron radioactive contamination. Therefore, "neutronless" reactions are the most promising.

3) 2 D+ 3 He -> 4 He (3.6 MeV) + p (14.7 MeV) - deuterium reacts with helium-3. The problem is that helium-3 is extremely rare. However, the neutron-free yield makes this reaction promising.

4) p+ 11 B -> 3 4 He + 8.7 MeV - boron-11 reacts with protium, resulting in alpha particles that can be absorbed by aluminum foil.

6. Where to conduct such a reaction?

The natural fusion reactor is the star. In it, the plasma is held under the influence of gravity, and the radiation is absorbed - thus, the core does not cool down.

On Earth, thermonuclear reactions can only be carried out in special facilities.

impulse systems. In such systems, deuterium and tritium are irradiated with ultra high power laser beams or electron/ion beams. Such irradiation causes a sequence of thermonuclear microexplosions. However, it is unprofitable to use such systems on an industrial scale: much more energy is spent on the acceleration of atoms than is obtained as a result of fusion, since not all accelerated atoms enter into a reaction. Therefore, many countries are building quasi-stationary systems.

Quasi-stationary systems. In such reactors, the plasma is held by a magnetic field at low pressure and high temperature. There are three types of reactors based on different magnetic field configurations. These are tokamaks, stellarators (torsatrons) and mirror traps.

tokamak stands for "toroidal chamber with magnetic coils". This is a camera in the form of a "donut" (torus), on which coils are wound. The main feature of the tokamak is the use of an alternating electric current that flows through the plasma, heats it up and, creating a magnetic field around itself, holds it.

IN stellarator (torsatron) the magnetic field is completely contained by magnetic coils and, unlike a tokamak, can be operated continuously.

W mirror (open) traps the principle of reflection is used. The chamber is closed on both sides by magnetic "plugs" that reflect the plasma, keeping it in the reactor.

For a long time, mirror traps and tokamaks fought for supremacy. Initially, the concept of a trap seemed simpler and therefore cheaper. In the early 60s, open traps were heavily funded, but the instability of the plasma and unsuccessful attempts to contain it with a magnetic field forced these installations to complicate these installations - seemingly simple designs turned into hellish machines, and it did not work out to achieve a stable result. Therefore, tokamaks came to the fore in the 1980s. In 1984, the European JET tokamak was launched, the cost of which was only 180 million dollars and the parameters of which made it possible to carry out a thermonuclear reaction. In the USSR and France, superconducting tokamaks were designed, which spent almost no energy on the operation of the magnetic system.

7. Who is now learning to carry out thermonuclear reactions?

Many countries are building their own fusion reactors. There are experimental reactors in Kazakhstan, China, the USA and Japan. The Kurchatov Institute is working on the IGNITOR reactor. Germany launched the Wendelstein 7-X stellarator fusion reactor.

The most famous international project is the ITER tokamak (ITER, International Thermonuclear Experimental Reactor) at the Cadarache Research Center (France). Its construction was supposed to be completed in 2016, but the amount of necessary financial support has grown, and the timing of the experiments has shifted to 2025. The European Union, the USA, China, India, Japan, South Korea and Russia. The main share in financing is played by the EU (45%), the rest of the participants supply high-tech equipment. In particular, Russia produces superconducting materials and cables, radio tubes for plasma heating (gyrotrons) and fuses for superconducting coils, as well as components for the most complex part of the reactor - the first wall, which must withstand electromagnetic forces, neutron radiation and plasma radiation.

8. Why do we still not use thermonuclear reactors?

Modern tokamak installations are not thermonuclear reactors, but research installations in which the existence and preservation of plasma is possible only for a while. The fact is that scientists have not yet learned how to keep the plasma in the reactor for a long time.

At the moment, one of the biggest achievements in the field of nuclear fusion is the success of German scientists who managed to heat hydrogen gas to 80 million degrees Celsius and maintain a cloud of hydrogen plasma for a quarter of a second. And in China, hydrogen plasma was heated to 49.999 million degrees and held for 102 seconds. Russian scientists from the (G. I. Budker Institute of Nuclear Physics, Novosibirsk) managed to achieve stable heating of the plasma up to ten million degrees Celsius. However, the Americans have recently proposed a method for confining plasma for 60 years - and this inspires optimism.

In addition, there is controversy regarding the profitability of fusion in industry. It is not known whether the benefits of electricity generation will offset the costs of fusion. It is proposed to experiment with reactions (for example, abandon the traditional deuterium-tritium or monopropellant reaction in favor of other reactions), structural materials - or even abandon the idea of ​​industrial thermonuclear fusion, using it only for individual reactions in fission reactions. However, scientists still continue to experiment.

9. Are fusion reactors safe?

Relatively. Tritium, which is used in thermonuclear reactions, is radioactive. In addition, neurons released as a result of fusion irradiate the reactor structure. The elements of the reactor themselves are covered with radioactive dust due to exposure to plasma.

However, a fusion reactor is much safer than a nuclear reactor in terms of radiation. There are relatively few radioactive substances in the reactor. In addition, the design of the reactor itself assumes the absence of "holes" through which radiation can leak. The vacuum chamber of the reactor must be sealed, otherwise the reactor simply cannot work. During the construction of thermonuclear reactors, materials tested by nuclear power are used, and reduced pressure is maintained in the rooms.