The word "TOKAMAK" is an abbreviation of the words TOROIDAL, CAMERA, MAGNETIC COILS, which describe the main elements of this magnetic trap, invented by A.D. Sakharov in 1950. The scheme of TOKAMAK is shown in Fig.4.
Figure 4. Scheme of principal units of TOKAMAK
The main magnetic field in the toroidal chamber containing hot plasma is generated by toroidal magnetic coils. An important role in plasma equilibrium is played by the plasma current, which flows along the toroidal plasma column and creates a poloidal magnetic field directed along the small bypass of the torus. The resulting magnetic field has lines of force in the form of endless spirals, covering the central line of the plasma torus - the magnetic axis. Thus, the magnetic field lines in TOKAMAK form closed, nested toroidal magnetic surfaces. The current in the plasma is maintained by a vortex electric field created by the primary winding of the inductor. In this case, the plasma coil plays the role of a secondary winding. It is obvious that the inductive maintenance of the current in TOKAMAK is limited by the reserve of the magnetic field flux in the primary winding and is possible only for a finite time. In addition to toroidal coils and the primary winding of the inductor, TOKAMAK should have poloidal windings, which are needed to maintain the equilibrium of the plasma and control its position in the chamber. The currents flowing in the poloidal coils create electromagnetic forces acting on the plasma current and thus can change its position in the chamber and the cross-sectional shape of the plasma column.
The first TOKAMAK was built in Russia at the Institute of Atomic Energy named after I.V. Kurchatov in 1956. Ten years of intense research and improvement of this device led to significant progress in the plasma parameters of TOKAMAKS. By 1968, TOKAMAK T-Z obtained a plasma temperature of 0.5 keV and achieved parameters that significantly exceed those achieved on other magnetic traps. From that moment, the active development of this direction began in other countries. In the seventies, TOKAMAKS were built following T-Z generation: T-7, T-10, T-11 in the USSR, PLT and DIII-D in the USA, ASDEX in Germany, TFR in France, JFT-2 in Japan, etc. Methods for additional plasma heating were developed on TOKAMAKS of this generation, such as injection of neutral atoms, electron and ion cyclotron heating, various plasma diagnostics, and plasma control systems have been developed. As a result, impressive plasma parameters were obtained on TOKAMAKS of the second generation: a temperature of several KeV, plasma densities exceeding 1020 m-3. The parameter ntE (Lawson's criterion) has reached the value 5 1018. In addition, TOKAMAK received an additional, fundamentally important element for the reactor - a diverter. With the help of currents in the system of poloidal turns, the magnetic field lines are brought out in a modern TOKAMAK into a special part of the chamber. The plasma divertor configuration is shown in Fig. 5 using the DIII-D TOKAMAK as an example.
Fig.5. Cross-section of a modern TOKAMAK DIII-D with vertically extended plasma and a divertor magnetic configuration.
The diverter makes it possible to better control the energy flows from the plasma and to reduce the entry of impurities into the plasma. An important achievement of this generation of TOKAMAKS was the discovery of modes with improved plasma confinement - the H-mode.
In the early 80s, the third generation of TOKAMAKS, machines with a large torus radius of 2-3 m and a plasma current of several MA, entered service. Five such machines were built: JET and TORUS-SUPRA in Europe, JT60-U in Japan, TFTR in the USA and T-15 in the USSR. The parameters of large TOKAMAKS are shown in Table 2. Two of these machines, JET and TFTR, were designed to work with tritium and obtain a thermonuclear yield at the level of Qfus = Psynthesis / Pcost = 1.
TOKAMAKS T-15 and TORUS-SUPRA have superconducting magnetic coils, similar to those that will be needed in the TOKAMAK reactor. The main physical task of machines of this generation was to study the confinement of plasma with thermonuclear parameters, clarify the limiting plasma parameters, gain experience in working with a divertor, etc. Technological tasks included: development of superconducting magnetic systems capable of creating a field with an induction of up to 5 T in large volumes , the development of systems for working with tritium, the acquisition of experience in removing high heat fluxes in a divertor, the development of systems for remote assembly and disassembly of the internal components of the installation, the improvement of plasma diagnostics, etc.
Table 2. Main parameters of large experimental TOKAMAKS. TOKAMAK TFTR has already completed its program and was stopped in 1997. The rest of the machines continue to work.
1) TOKAMAK T-15 has so far operated only in the regime with ohmic plasma heating and, therefore, the plasma parameters obtained on this facility are quite low. In the future, it is envisaged to introduce 10 MW of neutral injection and 10 MW of electron cyclotron heating.
2) The given Qfus is recalculated from the parameters of the DD plasma obtained in the setup to the DT plasma.
And although the experimental program on these TOKAMAKS has not yet been completed, this generation of machines has practically fulfilled the tasks assigned to it. TOKAMAKS JET and TFTR for the first time received a large thermonuclear power of DT reactions in plasma, 11 MW in TFTR and 16 MW in JET.
This generation of TOKAMAKS reached the threshold value Qfus = 1 and obtained ntE only several times lower than that required for a full-scale TOKAMAK reactor. In TOKAMAKS, they learned how to maintain a stationary plasma current using RF fields and neutral beams. The physics of plasma heating by fast particles, including thermonuclear alpha particles, was studied, the operation of the divertor was studied, and modes of its operation with low thermal loads were developed. The results of these studies made it possible to create the physical foundations necessary for the next step - the first TOKAMAK reactor, which will operate in the combustion mode.
Long-term studies of plasma confinement in TOKAMAKS have shown that the processes of energy and particle transfer across the magnetic field are determined by complex turbulent processes in plasma. And although the plasma instabilities responsible for the anomalous plasma losses have already been identified, the theoretical understanding of nonlinear processes is still insufficient to describe the plasma lifetime based on first principles. Therefore, to extrapolate the plasma lifetimes obtained in modern facilities to the scale of the TOKAMAK reactor, at present, empirical regularities - scalings - are used. One of these scalings, obtained using statistical processing experimental database from various TOKAMAKS, predicts that the lifetime increases with an increase in the plasma size, plasma current, plasma cross section elongation and decreases with an increase in the plasma heating power.
Scaling predicts that TOKAMAK, in which self-sustaining thermonuclear combustion will occur, should have a large radius of 7-8 m and a plasma current of 20 MA. In such a TOKAMAK, the energy lifetime will exceed 5 seconds, and the power of thermonuclear reactions will be at the level of 1-1.5 GW.
In order to achieve the conditions necessary for the flow. The plasma in the tokamak is held not by the walls of the chamber, which are not able to withstand the temperature necessary for thermonuclear reactions, but by a specially created combined magnetic field - a toroidal external and poloidal current field flowing through the plasma column. Compared to other installations that use a magnetic field to confine the plasma, the use of electric current is main feature tokamak. The current in the plasma provides heating of the plasma and maintaining the equilibrium of the plasma column in the vacuum chamber. This tokamak, in particular, differs from the stellarator, which is one of the alternative confinement schemes in which both toroidal and poloidal fields are created using external magnetic coils.
The tokamak reactor is currently being developed as part of the international scientific project ITER.
Story
The proposal to use controlled thermonuclear fusion for industrial purposes and a specific scheme using the thermal insulation of high-temperature plasma by an electric field were first formulated by the Soviet physicist O. A. Lavrentiev in the mid-1950s. This work served as a catalyst for Soviet research on the problem of controlled thermonuclear fusion. A. D. Sakharov and I. E. Tamm in 1951 proposed to modify the scheme by proposing theoretical basis thermonuclear reactor, where the plasma would have the shape of a torus and be held by a magnetic field. At the same time, the same idea was proposed by American scientists, but "forgotten" until the 1970s.
Currently, the tokamak is considered the most promising device for the implementation of controlled thermonuclear fusion.
Device
A tokamak is a toroidal vacuum chamber with coils wound around it to create a toroidal magnetic field. The vacuum chamber is first evacuated and then filled with a mixture of deuterium and tritium. Then using inductor a vortex electric field is created in the chamber. The inductor is the primary winding of a large transformer, in which the chamber of the tokamak is the secondary winding. The electric field causes current to flow and ignite in the plasma chamber.
The current flowing through the plasma performs two tasks:
- heats the plasma in the same way as it would heat any other conductor (ohmic heating);
- creates a magnetic field around itself. This magnetic field is called poloidal(that is, directed along the lines passing through poles spherical coordinate system).
The magnetic field compresses the current flowing through the plasma. As a result, a configuration is formed in which helical magnetic lines of force "wrap around" the plasma column. In this case, the step during rotation in the toroidal direction does not coincide with the step in the poloidal direction. Magnetic lines are not closed, they twist around the torus infinitely many times, forming the so-called "magnetic surfaces" of a toroidal shape.
The presence of a poloidal field is necessary for stable plasma confinement in such a system. Since it is created by increasing the current in the inductor, and it cannot be infinite, the time of stable existence of plasma in a classical tokamak is still limited to a few seconds. To overcome this limitation, additional methods have been developed to maintain the current. For this, injection into the plasma of accelerated neutral deuterium or tritium atoms or microwave radiation can be used.
In addition to toroidal coils, additional poloidal field coils. They are annular coils around the vertical axis of the tokamak chamber.
Heating by current flow alone is not enough to heat the plasma to the temperature required for thermonuclear reaction. For additional heating, microwave radiation is used at the so-called resonant frequencies (for example, coinciding with the cyclotron frequency of either electrons or ions) or the injection of fast neutral atoms.
Tokamaks and their characteristics
In total, about 300 tokamaks were built in the world. The largest of them are listed below.
USSR and Russia
Kazakhstan
- The Kazakhstan Materials Science Tokamak (KTM) is an experimental thermonuclear facility for research and testing of materials in energy load modes close to
Tokamak (TOroidal Chamber with Magnetic Coils) is a toroidal facility for magnetic plasma confinement. The plasma is held not by the walls of the chamber, which are not able to withstand its temperature, but by a specially created magnetic field. A feature of the tokamak is the use electric current, flowing through the plasma to create the poloidal field necessary for plasma equilibrium. In this it differs from the stellarator, in which both the toroidal and poloidal fields are created using magnetic coils.
Story
The term "tokamak" was introduced by Russian physicists Igor Evgenievich Tamm and Andrei Dmitrievich Sakharov in the 1950s as an abbreviation for the phrase "toroidal chamber with magnetic coils." The first tokamak was developed under the guidance of Academician L.A. Artsimovich at the Institute of Atomic Energy. IV Kurchatov in Moscow and demonstrated in 1968 in Novosibirsk.
At present, the tokamak is considered the most promising device for controlled thermonuclear fusion.
Device
A tokamak is a toroidal vacuum chamber with coils wound around it to create a (toroidal) magnetic field. Air is first pumped out of the vacuum chamber, and then it is filled with a mixture of deuterium and tritium. Then, with the help of an inductor, a vortex electric field is created in the chamber. The inductor is the primary winding of a large transformer, in which the tokamak chamber is the secondary winding. The electric field causes current to flow and ignite in the plasma chamber.
The current flowing through the plasma performs two tasks:
Heats the plasma in the same way as it would heat any other conductor (ohmic heating).
- Creates a magnetic field around itself. This magnetic field is called poloidal (that is, directed along lines passing through the poles of a spherical coordinate system).
The magnetic field compresses the current flowing through the plasma. As a result, a configuration is formed in which helical magnetic lines of force "wrap around" the plasma column. In this case, the step during rotation in the toroidal direction does not coincide with the step in the poloidal direction. The magnetic lines turn out to be open, they twist around the torus infinitely many times, forming the so-called. "magnetic surfaces" of toroidal shape.
The presence of a poloidal field is necessary for stable plasma confinement in such a system. Since it is created by increasing the current in the inductor, and it cannot be infinite, the time of stable existence of plasma in a classical tokamak is limited. To overcome this limitation, additional methods have been developed to maintain the current. For this, injection of accelerated neutral deuterium or tritium atoms into the plasma or microwave radiation can be used.
In addition to toroidal coils, additional poloidal field coils are needed to control the plasma filament. They are annular coils around the vertical axis of the tokamak chamber.
Heating by current flow alone is not enough to heat the plasma to the temperature required for a thermonuclear reaction to take place. For additional heating, microwave radiation is used on the so-called. resonance frequencies (for example, coinciding with the cyclotron frequency of either electrons or ions) or the injection of fast neutral atoms.
Controlled thermonuclear fusion
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 is controlled in contrast to explosive thermonuclear fusion (used in thermonuclear weapons). Controlled thermonuclear fusion differs from traditional nuclear energy in that the latter uses a fission reaction, during which lighter nuclei are obtained from heavy nuclei. In the main nuclear reactions, which are planned to be used for controlled thermonuclear fusion, will use deuterium (2H) and tritium (3H), and in the more distant future, helium-3 (3He).
The fate of nuclear fusion
The idea of creating a fusion reactor originated in the 1950s. Then it was decided to abandon it, since scientists were not able to solve many technical problems. Several decades passed before scientists managed to "force" the reactor to produce any fusion power.
Diagram of the International Thermonuclear Reactor (ITER)
The decision to design the International Thermonuclear Reactor (ITER) was made in Geneva in 1985. The USSR, Japan, the USA, united Europe and Canada are participating in the project. After 1991, Kazakhstan joined the participants. For 10 years, many elements of the future reactor have been manufactured at the military-industrial enterprises of developed countries. For example, Japan has developed a unique system of robots that can work inside the reactor. In Russia, a virtual version of the installation has been created.
In 1998, the United States, for political reasons, stopped funding its participation in the project. After the Republicans came to power in the country, and rolling blackouts began in California, the Bush administration announced an increase in energy investments. 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 announced that the US had changed its mind and intended to return to the project.
The project in terms of the number of participants is comparable to another major international scientific project- 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, it was decided to reduce the reactor power from 1.5 GW to 500 MW. Accordingly, the price of the project “lost weight”.
In June 2002 in Russian capital Symposium "Days of ITER in Moscow" was held. It discussed the theoretical, practical and organizational problems of the revival of the project, the success of which can change the fate of mankind and give it the new kind energy, in terms of efficiency and cost-effectiveness comparable only to solar energy.
If the participants agree on the place of construction of the station and on the start of its construction, then, according to the forecast of Academician Velikhov, by 2010 the first plasma will be obtained. Then it will be possible to start building the first thermonuclear power plant, which, under favorable circumstances, can produce the first current in 2030.
In December 2003, scientists involved in the ITER project gathered in Washington to finally determine the site of its future construction. The France Press news agency reported, citing one of the participants in the meeting, that the decision had been postponed to 2004. The next negotiations on this project will be held in May 2004 in Vienna. The reactor will begin to be built in 2006 and is planned to be launched in 2014.
Principle of operation
Fusion is a cheap and environmentally friendly way to produce energy. For billions of years, uncontrolled thermonuclear fusion has been taking place on the Sun - helium is formed from the heavy isotope of hydrogen deuterium. This releases an enormous amount of energy. However, people on Earth have not yet learned to control such reactions.
Plasma in a fusion reactor
Hydrogen isotopes will be used as fuel in the ITER reactor. During a thermonuclear reaction, energy is released when light atoms combine to form 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, hydrogen isotope atoms merge, turning into helium atoms with the release a large number neutrons. A power plant operating on this principle will use the energy of neutrons moderated by a layer dense matter(lithium)
The construction of the station will take at least 10 years and 5 billion dollars. France and Japan compete for the prestigious right to be the home of the energy giant.
Place of construction
Canada, Japan, Spain and France made proposals to host the reactor on their territories.
Canada justifies the need to place the reactor on its territory by the fact that it is in this country that there are significant reserves of tritium, which is a waste of nuclear energy. The construction of a fusion reactor will make it possible to dispose of them.
In Japan, according to the Kyodo Tsushin news agency, three prefectures were in a desperate struggle for the right to build a reactor at home. At the same time, residents northern island Hokkaido opposed the construction of it on their land.
In November of this year, the European Union recommended the French city of Cadarache as a future construction site. However, it is difficult to predict how the vote will go. Experts are expected to make their decision based on purely objective scientific facts, however, political overtones may also affect the vote. The US has already spoken out against giving the construction of the reactor to France, recalling its divisive behavior during the conflict in Iraq.
“We have an already existing scientific and technical structure, competence and experience, which is the guarantor of meeting the deadlines,” said the French Minister of Research.
Japan also has a number of advantages - Rokkasho-mura is located next to the port and next to the US military base. In addition, the Japanese are ready to invest much more money in the project than France. "If Japan is chosen, we will cover all the necessary expenses," said the Minister of Science and Education of Japan.
A French government spokesman told reporters that he had held "very intense high-level talks" ahead of the meeting. However, according to some reports, all countries except the European Union prefer Japan to France.
Environmental Safety
The new installation, according to scientists, is environmentally safer than nuclear reactors operating today. Helium is produced as spent fuel in the ITER facility, and not its isotopes, which must be stored in special storage facilities for decades.
Scientists believe that the fuel reserves for such power plants are practically inexhaustible - deuterium and tritium are easily mined from sea water. A kilogram of these isotopes can release as much energy as 10 million kg of fossil fuel.
– a device for carrying out a thermonuclear fusion reaction in a hot plasma in a quasi-stationary mode, with the plasma being created in a toroidal chamber and stabilized by a magnetic field. The purpose of the installation is the conversion of intranuclear energy into thermal energy and then into electrical energy. The word “tokamak” itself is an abbreviation of the name “magnetic toroidal chamber”, however, the creators of the installation replaced the “g” with “k” at the end, so as not to evoke associations with something magical.
Atomic energy (both in a reactor and in a bomb) a person receives by separating the nuclei heavy elements to lighter ones. The energy per nucleon is maximum for iron (the so-called "iron maximum"), and since maximum in the middle, then energy will be released not only during the decay of heavy, but also when light elements are combined. This process is called thermonuclear fusion, it takes place in a hydrogen bomb and a thermonuclear reactor. There are many known thermonuclear reactions, fusion reactions. The source of energy can be those for which there is inexpensive fuel, and there are two fundamentally different ways to start the fusion reaction.
The first way is “explosive”: part of the energy is spent on bringing a very small amount of matter to the required initial state, a synthesis reaction occurs, the released energy is converted into a convenient form. Actually, this is a hydrogen bomb, only weighing a milligram. Use as source of initial energy atomic bomb it can not be "small". Therefore, it was assumed that a millimetric tablet of deuterium-tritium ice (or a glass sphere with a compressed mixture of deuterium and tritium) would be irradiated from all sides by laser pulses. In this case, the energy density on the surface must be such that the plasma upper layer the tablet turned out to be heated to a temperature at which the pressure on the inner layers and the heating of the inner layers of the tablet itself would be sufficient for the synthesis reaction. In this case, the pulse must be so short that the substance that has turned into a plasma with a temperature of ten million degrees in a nanosecond does not have time to scatter, but presses on the inside of the tablet. This inner part compresses to a density one hundred times greater than the density solids, and heats up to a hundred million degrees.
Second way. The initial substances can be heated relatively slowly - they will turn into plasma, and then energy can be introduced into it in any way, until the conditions for the start of the reaction are reached. For a thermonuclear reaction to proceed in a mixture of deuterium and tritium and obtain a positive energy output (when the energy released as a result of a thermonuclear reaction turns out to be greater than the energy spent on this reaction), it is necessary to create a plasma with a density of at least 10 14 particles / cm 3 (10 - 5 atm.), and heat it up to about 10 9 degrees, while the plasma becomes completely ionized.
Such heating is necessary so that the nuclei can approach each other, despite the Coulomb repulsion. It can be shown that in order to obtain energy, it is necessary to maintain this state for at least a second (the so-called "Lawson criterion"). A more precise formulation of the Lawson criterion is that the product of the concentration and the maintenance time of this state should be on the order of 1015 sCh cm–3. The main problem is the stability of the plasma: in a second it will have time to expand many times, touch the walls of the chamber and cool down.
In 2006, the international community starts building a demonstration reactor. This reactor will not be a real source of energy, but it is designed in such a way that after it - if everything works fine - it will be possible to start building "energy", i.e. intended for inclusion in the power grid, thermonuclear reactors. The largest physical projects (accelerators, radio telescopes, space stations) become so expensive that consideration of the two options is beyond the means of even humanity, which has united its efforts, so a choice has to be made.
The beginning of work on controlled thermonuclear fusion should be attributed to 1950, when I.E. Tamm and A.D. Sakharov came to the conclusion that it is possible to realize CTS (controlled thermonuclear fusion) using magnetic confinement of hot plasma. At the initial stage, work in our country was carried out at the Kurchatov Institute under the leadership of L.A. Artsimovich. The main problems can be divided into two groups - problems of plasma instability and technological problems (pure vacuum, resistance to radiation, etc.). The first tokamaks were created in 1954-1960, now more than 100 tokamaks have been built in the world. In the 1960s, it was shown that only by means of heating due to the passage of current ("ohmic heating") it is impossible to bring the plasma to thermonuclear temperatures. The most natural way to increase the energy content of plasma seemed to be the method of external injection of fast neutral particles (atoms), but only in the 1970s was the necessary technical level reached and real experiments using injectors. Now the most promising are the heating of neutral particles by injection and electromagnetic radiation in the microwave range. In 1988, the T-15 pre-reactor generation tokamak with superconducting windings was built at the Kurchatov Institute. Since 1956, when during the visit of N.S. Khrushchev to Great Britain I.V. Kurchatov announced that these works were being carried out in the USSR. work in this area is carried out jointly by several countries. In 1988, the USSR, the USA, the European Union and Japan began designing the first experimental tokamak reactor (the installation will be built in France).
The dimensions of the designed reactor are 30 meters in diameter and 30 meters high. The expected construction time of this plant is eight years and the operation life is 25 years. The volume of plasma in the installation is about 850 cubic meters. The plasma current is 15 megaamperes. The thermonuclear power of the installation of 500 megawatts is maintained for 400 seconds. In the future, this time is expected to be increased to 3000 seconds, which will make it possible to carry out the first real research physics of thermonuclear fusion ("thermonuclear combustion") in plasma.
Lukyanov S.Yu. Hot plasma and controlled nuclear fusion. M., Science, 1975
Artsimovich L. A., Sagdeev R. Z. Plasma Physics for Physicists. M., Atomizdat, 1979
Hegler M., Christiansen M. Introduction to controlled thermonuclear fusion. M., Mir, 1980
Killin J. Controlled thermonuclear fusion. M., Mir, 1980
Boyko V.I. Controlled thermonuclear fusion and problems of inertial thermonuclear fusion. Soros educational journal. 1999, No. 6
We know that the Russian words "beluga", "vodka", "samovar" entered into foreign languages Without translation. But, apart from irony, it causes nothing. Another thing is such an "untranslatable" word as "satellite", showing the high potential of domestic science and technology. But the "satellite" is already in the past. Is there a new term that can cause pride in the country?
200 thousand kWh of electricity is enough to meet all the needs of a modern European for 30 years. To generate this amount of electricity, one bath of water (45 liters) and as much lithium as it is contained in one computer battery is enough. But with current technologies for generating energy from fossil fuels, it takes 70 tons of coal.
There is another word that is pronounced the same in all languages - “tokamak”. The Russian abbreviation gave the name to numerous installations built around the world in which the plasma is held in the process of thermonuclear fusion by a magnetic field. Tokamak is also called the future reactor of the international ITER project, which should give mankind access to a practically inexhaustible source of energy.
"This is Russian word, - tells the participants of the press tour in international organization ITER ( International thermonuclear experimental reactor. - Aut. ) Robert Arno from Communications. “And what does it mean, my colleague from Russia will say.”
And Alexander Petrov, representative of the Russian Design Center ITER, willingly explains: "Toroidal camera with magnetic coils!" Then he had to repeat this more than once into voice recorders and cameras of journalists from Europe, Korea, China, Canada ...
How does synthesis take place?
The idea of a tokamak was proposed by academician Lavrentiev, and it was finalized Andrey Sakharov and Igor Tamm. If the current technologies of nuclear energy are based on a decay reaction, when lighter nuclei are formed from heavier nuclei, then in thermonuclear fusion, on the contrary, light atomic nuclei combine to form heavier ones.
Basically, we are talking about isotopes of hydrogen - deuterium and tritium. The nucleus of the first consists of a proton and a neutron, and the nucleus of the second consists of a proton and two neutrons. Under normal conditions, identically charged nuclei, of course, repel each other, but at ultrahigh temperatures, on the contrary, they unite. As a result, a helium nucleus plus one free neutron is formed, but most importantly, a huge amount of energy is released, which the atoms used to spend on interacting with each other. Deuterium is easily “gotten” from water, and tritium is more unstable, therefore it is produced inside the installation due to the reaction with lithium.
One thermonuclear reactor - the Sun - gave mankind the opportunity to live on our planet, warming with its warmth. In the center of the star, where a very high plasma density is achieved under the influence of gravity, the reaction proceeds at a temperature of 15 million ° C. On Earth, it will not be possible to achieve such a density - it remains only to increase the temperature. In the reactor of the ITER project, it should reach 150 million ° C - 10 times higher than in the solar core!
Can anyone other than physicists imagine such a thing? And what of the possible materials on Earth can withstand it? There's no such thing. That is why the tokamak was invented. Its vacuum chamber in the shape of a hollow "donut" is surrounded by superconducting electromagnets - they create toroidal and poloidal magnetic fields that do not allow hot plasma to touch the walls of the chamber. There is also a central electromagnet - an inductor. A change in the current in it causes the movement of particles in the plasma, which is necessary for synthesis.
Fuel for thermonuclear fusion needs a minimum, and safety is much higher than with current technologies. After all, the density of the plasma is very low (a million times lower than the density of the atmosphere!) - accordingly, there can be no explosion. And at the slightest decrease in temperature, the reaction stops - then the plasma, as physicists say, simply “crumbles”, without causing any harm environment. In addition, fuel will be loaded continuously, that is, the operation of the reactor can be easily stopped at any time. radioactive waste it practically does not produce.
How long is the way?
Since the late 60s, when the success of Soviet physicists in the field of controlled thermonuclear reaction became obvious, tokamaks appeared not only in Russia, but also in Kazakhstan, the USA, Europe, Japan, and China. They proved that it is real to create and hold a high-temperature plasma in which the reaction takes place. However, so far the hold has been short, counting in seconds, and also costly in terms of energy spent on warming up. For science, such results were sufficient, but not for humanity to step into a new energy era.
And then the idea of an international project was born, the main task of which is to build a reactor capable of generating energy in volumes much larger than necessary to maintain a thermonuclear reaction. Q ≥ 10 - this is how physicists formulate it.
The beginning was laid in 1985 at a meeting of the heads of the USSR and the USA. The project was called the International Thermonuclear Experimental Reactor: ITER - in English transcription, ITER - in Russian. It solves a common problem for all mankind, and the scale is such that one country cannot pull it off, and therefore it has become international. Today it involves the EU countries, China, India, Japan, the Republic of Korea, Russia and the United States. The participation of each party is determined: Europe - 45%, the rest - 9% each with a small, but it is expressed not in currency, but in a tangible contribution - the work performed or the equipment manufactured.
It took decades for the project to line up and "draw" - on paper, in 3D models. And now its features and lines are drawn on a real site in the south of France, next to the Cadarache research center, which has its own tokamak.
What is our contribution?
The smell of Provencal herbs envelops the hilly landscape, including an impressive area (42 hectares, or 60 football fields) with five huge tower cranes, where the construction of buildings, of which there will be 39, is in full swing. By 2020, it should be completed, but equipment will start to arrive earlier - as certain stages are completed.
The main deliveries from Russia fall on schedule for 2016-2017. Our country participates in the construction of all the main structures of the megatokamak, manufactures superconductors, and creates testing and diagnostic systems. More than 30 Russian enterprises and organizations are involved in this, most of them are subsidiaries of the Rosatom State Corporation. After all, it was in the nuclear industry, despite the hard times experienced by the country, that it was possible to maintain a high scientific and production potential.
“As part of Russian obligations, 25 systems for ITER are being manufactured. These are not experiments and not R & D - this is equipment that must be delivered to Cadarache on time, ” says Anatoly Krasilnikov, head of the ITER Project Center - the Russian agency ITER.
The equipment itself is unique - in most cases, completely new technologies are being developed to create it. For example, the first wall of the blanket ("blanket") of the plasma chamber, which will have the maximum temperature load. What materials can withstand? What nuances should be included in the design? These questions have already been answered at the Research Institute of Electrophysical Equipment. D. V. Efremova (NIIEFA). The wall will be made of beryllium, and not solid, but cut into small square plates - so that the material can “breathe” more easily and it does not crack from high temperatures, like the earth in the summer heat.
Another serious task that Rosatom scientists and specialists have already solved is the combination of different materials with each other: beryllium - bronze, copper - stainless steel, tungsten - copper. Conventional welding is not suitable for the conditions of the project, so copper is welded onto tungsten in a vacuum chamber, steel is connected to copper using the “explosion welding” method - then a single metal block is formed that can no longer be separated even at ultra-high temperatures.
Participation in the project is a serious impetus not only for domestic science, but also for the country's economy, since it makes it possible to step to a different level of technology and production, and sometimes even jump. For example, in 4 years at the Chepetsk Mechanical Plant, they mastered the production of products from titanium alloys from scratch. Last year, our nuclear scientists have already completed deliveries of superconducting strands for ITER. Thanks to participation in the project, a new - complex and expensive - range of products was launched at the plant, which significantly increased the company's income.
Why slippage?
Actually, the desire to master the technology largely explains the international cooperation in the project. Indeed, regardless of who was involved in the development or production of a particular part or design, the created technologies become a common intellectual product for all participating countries and can be used by them for other purposes.
True, the democratic conditions of participation and the lack of a general budget for the project turned into the fact that not everyone copes with their obligations on time. There were delays and disagreements. And if there are no complaints about Russia, it is the most obligatory party in the project, then in the same Europe there has been a noticeable lag.
The originally scheduled dates have also been pushed back. It is already unrealistic to get the first plasma by 2020, and the first energy in the grid by 2027. Of course, this is largely due to the innovation of the project - no one in the world has done anything like this before. And it is natural that life makes its own adjustments to paper calculations. But, on the other hand, there is also an elementary optionality. The new one intends to exclude it CEO of the project Bernard Bigot. According to him, by the end of this year, an adjusted schedule should be approved and the project management system should be revised. He does not exclude that some works can be redistributed among the participants.
“We thought that meeting the deadlines would be possible simply due to good faith and good intentions. Now we realized that without strict management nothing will come of it. But it's not about who will manage whom - we must learn to work together,” says B. Bigo.
Why dream?
The new CEO is one of those scientists who not only believe in the project, but are convinced of its success. "There is no Plan B, there is no alternative," he said. - We can make adjustments. But this is the real story."
The reality is called the project and hundreds of our scientists and specialists. How else? Indeed, in the ITER organization there is nothing but an office building and a construction site. But in our Rosatom research institutes and at its enterprises, as well as in other organizations and companies involved in the project, they do. They have already made superconductors, released hitherto unseen cables, where hundreds of twisted wires are placed in a sheath of copper and steel, and started winding coils. Recently, in the St. Petersburg NIIEFA, a prototype of resistors for the rapid output of energy from the windings of the magnetic system was successfully tested, and in Nizhny Novgorod at NPP "Gikom" - testing a prototype gyrotron complex for generating current and heating plasma. At the TRINITI institute, diamond detectors for the vertical neutron chamber have acquired real features.
However, reality and dream in ITER are inseparable from each other. For scientists and specialists who are passionate about their work, the project not only opened up new perspectives - it spiritualized them. Evgeny Veshchev, a specialist in diagnostics, recalls how, as a student at MEPhI, he first saw a tokamak and listened to a lecture on the prospects for thermonuclear energy. He was simply inspired when he learned about the project, and thought: “How great it is to be involved in such an important cause for humanity!” And now he is happy, because every day he contributes to it.
"Dreams can be costly - like the Apollo mission or the NASA programs," enthuses Mark Hendersson, Head of the Electron Cyclotron Section. - But we must dream! Including about the new nuclear fusion, which can be called the Prometheus of today.
Expert opinion:
Sergey Kiriyenko, General Director of the State Corporation "Rosatom":
It is necessary to combine the efforts of all participants in order to ensure the development of our industry, to form a new generation in it, while combining money, time, and most importantly, experience.
We must all join forces to implement such international projects as INPRO under the auspices of the IAEA or the ITER project implemented in France.
