Diamond: A Secret Weapon in Nuclear Fusion Reactors

The production of traditional fossil fuels, such as coal, oil, natural gas, and other resources, continues to decline, and the emission of large amounts of greenhouse gases will also exacerbate global warming, making energy issues increasingly severe. In order to address this challenge, countries around the world have begun to develop new energy sources, and nuclear fusion reaction, as a new type of clean energy, has attracted much attention. In this highly specialized research field, there is a little-known aspect involved - diamond, which is precisely an indispensable material for nuclear fusion technology.

However, nuclear fusion reactions require very high temperatures and pressures to occur. The ideal fusion conditions require temperatures to reach hundreds of millions of degrees Celsius and air pressure to reach several hundred times atmospheric pressure. Such conditions are extremely difficult and expensive to achieve, and in such extreme environments, only one material can bear this heavy responsibility, which is diamond.

Researchers at the Karlsruhe Institute of Technology (KIT) have developed a so-called cyclone tube for the ITER reactor. Cyclotron is a microwave oscillator that can generate temperatures up to 150 million degrees Celsius in a reactor, similar to a giant microwave oven. This high temperature can bring tritium fuel to the plasma state required for melting. In order to guide microwave radiation from the gyrotron into the plasma and keep radioactive tritium inside the reactor under vacuum, they developed a diamond disk for window units to heat the plasma in nuclear fusion reactors. So far, no other material has been found to exist under such extreme microwave radiation. Even if it can exist stably, it may not necessarily have excellent permeability and low loss like diamond.

The diamond disc is formed using a special coating technique - chemical vapor deposition (CVD) method. In a gas environment, diamond will deposit onto the silicon surface in a vacuum reactor for growth. Through microwave radiation, diamond can become plasma, similar to a fusion reaction occurring in a reactor, but with much less energy consumption. Plasma contains many hydrogen atoms, which can effectively suppress the formation of graphite.

The application of diamond materials in nuclear reaction technology is not yet exhausted and further exploration is needed. Diamond is one of the special materials that exist in nature, with the highest hardness, low friction coefficient, high elastic modulus, high thermal conductivity, high insulation, wide energy gap, high sound propagation rate, and good chemical stability. Although natural diamonds possess these unique characteristics, they have always existed only in the form of gemstones, and the variability and rarity of their properties greatly limit their applications.

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