Scientists from the Massachusetts Institute of Technology (MIT), along with colleagues from the startup company Commonwealth Fusion Systems (CFS) and Bill Gates, who supports them financially, have taken a truly seven-mile step forward towards creating a workable thermonuclear reactor – “inexhaustible source of energy ”, as this dream of mankind is called, which began to seem unrealizable. They created a kind of dream magnet for him based on high-temperature superconducting materials. During the tests, which took place on September 5, the magnet generated a magnetic field with a strength of 20 Tesla – almost a million times larger than the earth's.
The achievement is by no means a record – in laboratories, scientists have generated fields of almost 3 thousand Tesla. The main advantage of the new magnet is that it is very compact for its power – a couple of meters across.
A new material – a high-temperature superconductor tape made of yttrium-barium-copper oxide (YBCO) – made it possible to reduce the size of the main part of the fusion reactor. It does not require extreme cooling.
For comparison, the diameter of the magnet for the international experimental thermonuclear reactor (IETR) under construction in France, made of a more traditional low-temperature superconductor, will be about three times larger. And “give out” 13 Tesla.
Scientists believe that 13 Tesla is enough to hold the thermonuclear plasma, and 20 – even with a margin. But the reactor, which will be based on high-temperature superconductors and a more compact magnet, will be simpler and lighter.
SPARC is the name given by the MIT-CFS collaboration to a power plant, in which specialists want to assemble a circular plasma channel from 16 magnetic sections. They plan to launch it by 2025. Energy is promised to produce 100 megawatts – several times more than spent on maintaining the operation of the reactor.
In fact, both SPARC and ITER are tokamaks – toroidal chambers with magnetic coils – installations invented in Soviet times by Soviet scientists. Since then, they have been trying to make them workable in many countries of the world. But unsuccessfully. Thermonuclear plasma in such installations flashed, but for a split second. And then it “stuck” to the walls and went out.
Perseverance won out in the end. Already in our time, researchers have made significant progress – some kept burning for almost a minute. Mainly due to the appearance of superconductors and more powerful magnets based on them.
From the current development of the MIT-CFS collaboration to a stably operating power plant is already, as they say, a stone's throw.
REFERENCE “KOMSOMOLKA”
Sun in a magnetic bottle
The reaction in a thermonuclear reactor – a fusion reaction – is similar to that which occurs in the interior of the sun. The nuclei of lighter atoms fuse to form heavier ones, while releasing a huge amount of energy.
Experimental power plants still use hydrogen isotopes – deuterium and tritium. Merging, their nuclei form helium nuclei and many neutrons.
In the future, it may be possible to carry out a more efficient thermonuclear fusion based on the fusion of deuterium and helium-3 nuclei with the formation of nuclei again.
The mixture required for synthesis is injected into a toroidal chamber and heated with an electric current to several hundred million degrees. Plasma is formed, in which the process of thermonuclear fusion takes place. The magnetic field holds the plasma, preventing it from touching the metal walls of the toroidal chamber. This design is also called a “magnetic bottle”.
