Russian physicists from the A. F. Ioffe Physicotechnical Institute in St. Petersburg described ionic processes of heat transfer in a spherical tokamak. The results of the study, which brings scientists one step closer to solving the problem of thermonuclear fusion, are published in the journal Plasma Physics and Controlled Fusion.
If scientists succeed in realizing the idea of controlled thermonuclear fusion, humanity will receive an almost inexhaustible source of energy. Fusion power plants are recognized as safe and environmentally friendly: compared to nuclear power plants, they do not have explosive reactions, and unlike the combustion of hydrocarbons, there are no emissions of carbon dioxide and nitrogen oxides that contribute to global warming and pollute the environment. Moreover, neutrons obtained from thermonuclear fusion can destroy radioactive waste at nuclear power plants.
Experiments on thermonuclear fusion are carried out all over the world in special installations - tokamaks, inside which a gas of light elements - hydrogen, deuterium and tritium - is heated to a temperature of 100 million degrees, which makes it possible to form a plasma - a gas of charged particles: ions and electrons. The heated plasma ions collide with each other in the same way as it happens in the interior of the Sun. In this case, helium nuclei are formed and neutrons are released, and the neutron energy, which exceeds the cost of heating the plasma, can be used in industry and power engineering.
The main task of physicists is to learn how to keep plasma inside thermonuclear installations using a strong magnetic field for a relatively long time. And for this you need not only to know what processes are taking place in this plasma, but also to have their mathematical description in order to be able to control them. In addition, knowledge of ionic processes in plasma is necessary for the design of large facilities such as the international experimental thermonuclear reactor ITER.
The AF Ioffe Physicotechnical Institute has a unique experimental thermonuclear installation - the Globus-M spherical tokamak, designed to study the behavior of plasma in laboratory conditions, and not in reactor mode.
The staff of the Institute investigated and described the process of ionic heat exchange in the plasma of the Globus-M tokamak. This work was supported by a grant from the Presidential Program of Research Projects of the Russian Science Foundation (RSF).
“We have confirmed that the peculiarities of the physical processes in the plasma of the Globus-M spherical tokamak prevent the occurrence of additional heat losses through the ion channel due to plasma turbulence. This means that an installation of this type is a good basis for creating a compact source of thermonuclear neutrons,”the head of the research, candidate of physical and mathematical sciences Gleb Kurskiev, quoted in a press release from the Russian Science Foundation.
The better the heating of the plasma, the more efficient the fusion is, and this requires a strong magnetic field and an electric current flowing through the plasma. On the contrary, the turbulence of plasma ions interferes with effective heating: instead of useful collisions, the ions are deflected and leave the plasma, which violates its thermal insulation. In their work, scientists have assessed the degree of heat transfer in the Globus-M spherical tokamak.
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“The experimentally proven model for calculating the parameters of plasma heating will allow us to design a compact source of high-energy neutrons that can be used for fission of heavy nuclei. Energy can also be obtained in the process. Our research will significantly accelerate the development and implementation of more efficient nuclear systems using both fusion and fission processes,”explains Gleb Kurskiyev.
The scientists' research complements the fundamental knowledge gained from experiments on similar European and American installations. By combining the results of experiments, in the future it will be possible to design a more advanced device for nuclear fusion reactions, scientists say.