Why are the prospects of fusion energy only when the world will be the first "reactors of the future" and how scientists from Novosibirsk to approximate the onset of the day?
Today, the world is a lot of research to answer the question of where humanity will get energy after the end of oil and gas. Coal-fired thermal power station polluting the atmosphere and affect the ecology, plant and so are already in almost all major rivers, nuclear disaster population considers dangerous, and solar and wind energy can not provide commercial volumes. Therefore, the only promising option for future power plants are fusion reactors. And the Institute of Nuclear Physics is actively brings the incarnation of fusion energy research ideas into real life.
I will begin with the history of this process. Academician Budker (founder and first director of the Institute of Nuclear Physics) in the 50-ies of the last century, invented a magnetic trap to keep the high-temperature plasma. The trap consisted of two magnetic coils that formed between a "magnetic hole" where the plasma particles could under certain conditions persist indefinitely. However, in fusion devices is a major amount of particle collisions leading to fusion reactions. Collisions lead to the spreading of the particles, they begin to leave the trap. Therefore, further development of this theme have been associated with the search for ways to slow down the motion of the particle. One way to improve the retention of particles — the multi-mirror trap proposed by Budker and his students.
This idea was tested in the Institute of Nuclear Physics at the facility "Goldfinch", which worked with the cold plasma. Followed by installation of the GOL-1, now works at the Institute of GOL-3 (which is unique in the world today is not), but after a few years it will be completed the construction of the next generation, which previously named GDML.
To start the fusion reaction, the plasma must be heated. In GOL-3 is done by powerful electron beams. During this process the temperature reaches 2 keV ion — is more than 23 millions of degrees that corresponds to a temperature approximately in the center of the Sun. And now we do experiments to increase the basic fusion parameters — density, temperature, residence time, etc.
Initially similar design were not only in the USSR but also in the U.S. and Europe, but then decided to develop the world's competitive technology so-called tokamaks. This — toroidal structure in which a magnetic field is retained plasma. It is heated to high temperatures (above 100 million degrees), and then start the thermonuclear reaction. However, there are serious shortcomings in tokamaks. Thus, while developers tokamak can not increase the density of the plasma — it becomes unstable and pops up on the walls and in the world as long as there is no material capable of withstanding strong heated plasma flows. The only way — is to increase the size of the tokamak, but it greatly increases the cost and construction time. For example, in France, is now the international project to build a new generation of ITER tokamak — its launch is planned for 2020, but the timing is always shifting, and the price has already reached 15 billion euros.
Open the trap that we use for research, have obvious advantages. They have open ends through which the plasma can escape from the trap, and materials capable of withstanding modern plasma flows that occur in such devices. That is, open the trap, compared with tokamaks, engineering reflects the simplicity and low cost of construction.
What is the main objective of our research? Create a fusion reactor that produced a commercially available heat and electricity — and cheaper than tokamaks. However, the solution of this problem — it is not coming years. If tests GDML after 5 years will be successful, at least another 10 years will be spent on the construction of the next generation. You will need to create a demonstration reactor, which must show that can be used to generate heat and electricity. Moreover, its performance should be at least 2000% (for comparison GDML efficiency of the plant will reach only a few percent).
Only then will start construction of commercial reactors. So if any of breakthrough discoveries in the research process is not done, then the best of today's experiments to the real work of commercial fusion reactors will be more than 30 years.
However, it is now possible to imagine how would look first thermonuclear station. The raw material for them can be plain water: each 5500th its molecule contains deuterium (stable isotope of hydrogen), which can be easily removed and stored in a gaseous form. The plasma can be either a deuterium-tritium or deuterium-deuterium mixture. The first reactors are used tritium, because the mixture requires less burning temperature (about 100 million degrees). However, the problem is that the natural reserves of the radioactive tritium on Earth is not, however, countries with nuclear reactors and nuclear waste processing technologies, there is a certain amount of tritium. A further fusion plant will turn out for themselves tritium themselves — of the very common in the world of lithium by irradiation by neutrons. By the way, another advantage of open traps to tokamaks in them in the future, do not interfere with the work of deuterium-deuterium reactions, which in closed systems are considered futile, as they require a higher temperature plasma.
In general, the dream of physicists termoyaderschikov — is aneutronic reaction in which all of the products have a charge, and therefore do not leave the reactor and are retained therein. In this case, the reactor is weakly radioactive. For example, such a reaction would come up the proton and boron-11, but it will take a temperature of more than a billion degrees, yet unattainable. Either use a low-temperature reaction of deuterium and helium-3, but also has the disadvantage of this reaction — Helium-3 is almost absent in the world, but it can be mined on the moon.
One of the major issues that may arise in fusion reactors — is the level of security. But compared to plant they are much less hazardous. First, use a very small amount of tritium (ITER tokamak in France will use no more than 500 grams), and deuterium not radioactive. Even in the case of capture station conditional terrorists they will get at the disposal of only small amounts of radioactive substances, which also breaks down during storage (half-life of tritium in 12 years). Blow up a fusion reactor by increasing the temperature in the reactor is also impossible, because the contact with the wall of a thermonuclear plasma chamber or air instantly cools the plasma and stop the reaction. And the radiation that accompanies the current work fusion power station will be limited to one room, which will serve robots. Thus, in the case of any emergency situation for a fusion reactor, a significant release of radioactive substances is not possible.
Andrew Shoshin, Candidate of Physical and Mathematical Sciences, Fellow Institute of Nuclear Physics SB RAS, Novosibirsk State University Senior Lecturer