New Ideas of "Tungsten" in Foreign Nuclear Fusion Reactor

Scientists at a British university are experimenting with tungsten in a world-class new facility to help develop a new fusion reactor, ITER. ITER refers to the International Thermonuclear Fusion Experimental Reactor, which is known as the "artificial solar" project. Many countries involved in the research believe that if the "artificial sun" can be realized, it will produce almost unlimited clean energy, which is inexpensive and incalculable.

At present, tungsten is an important protective material for the first wall of plasma in the main international schemes. Pure tungsten materials not only have common properties of general metals, such as conductivity, thermal conductivity, plasticity and metallic luster, but also have high density, high melting point, high thermal conductivity, low vapor pressure, low thermal expansion coefficient, strong absorption ability and sputtering threshold, and good corrosion resistance.

In a fusion reactor, heavy hydrogen (deuterium and tritium) isotopes are fused to synthesize helium. This clean energy in the form of heat is released. Fusion reactor exhaust must be able to withstand a large amount of heat and particles. Nevertheless, the reactor wall always absorbs some fusion fuel. For safety reasons, only a limited amount of fuel may exist in the reactor, and physicists are trying to minimize the amount of hydrogen absorbed by wall materials. Therefore, advanced future reactor ITER will be equipped with exhaust gas made of tungsten metal. Tungsten has a high melting point, is a good thermal conductor and absorbs very little hydrogen, although this absorption can be increased by several orders of magnitude under the influence of neutrons from fusion reactions.

But by simulating the damage caused by high-energy neutrons and alpha particles produced during fusion, researchers found that tungsten tends to become brittle, leading to failure. Researchers believe that at this time, although tungsten is a major candidate material, they have not seen how it can be used as a structural material. We can use it as a first wall material barrier, but not for any other material with reasonable structure. In fact, it is a well-known fact that most Chinese scientists have elaborated on many related academic papers consulted by the editors.
British scientists believe that the answer is to develop a new type of alloy that combines tungsten (with ideal properties of extremely high hardness and melting point) with other materials that can prevent brittle radiation damage and nuclear transformation reaction, and forms a new protective shield layer, which further reduces the chance of hydrogen particles being absorbed by tungsten and thus prolongs the execution time. In the meantime, this will do twice as much for the operation of the reactor with half the effort.

Although the experimental conditions are very similar to those in the reactor exhaust, they are not the same. For example, particles in large-scale fusion reactors may collide with more energetic tungsten. In the future, we will focus on the influence of particle energy and surface temperature on the hydrogen absorption of tungsten, and reduce the hydrogen atom penetration into deeper metal layers. The reduction will be 1 million times less than the current research results, so the duration will be longer. New research on Tungsten by British scientists may help to promote this breakthrough.

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