A lot of people have played a game as a child.

During the Chinese New Year, the firecrackers are lit, and then the firecrackers are covered with a basin, but the firecrackers are blown up.

To put it simply, the fusion reactor is similar to this, and the first wall material is the basin.

The first wall material has two core problems, high-energy neutron irradiation and high-flux deuterium-tritium (plasma bombardment.

In terms of high-energy neutron irradiation.

What is currently being studied is basically the easiest form of D-T fusion to achieve: each D-T fusion produces a neutron of 14.1 MeV. Since the neutrons are not charged, they cannot be confined by a magnetic field, and they will be directly bombarded on the first wall material and cause damage.

Each D-T fusion produces a neutron of 14.1 MeV. Since the neutrons are not charged, they cannot be confined by a magnetic field, and they will be directly bombarded on the first wall material and cause damage.

14.1 MeV is a very large energy, you should know that the atoms in the material are bound by various chemical bonds, and the bond energy is about 1-10eV.

In other words, a neutron of 14.1 MeV carries enough energy to break millions of ordinary chemical bonds, which will undoubtedly cause irreparable damage to the material.

In fusion reactors, high-energy neutrons are like bullets fired at the material, constantly hitting metal atoms, breaking the chemical bonds around them, forcing them to leave their original positions, thus destroying the entire atomic arrangement.

When the atoms are knocked away, there is naturally a vacancy in the original place, and one by one these pits accumulate inside the material, turning into large holes.

In addition, the atoms that are knocked away do not be small, but diffuse to the surface of the material in various ways. As the atoms continue to move from the center to the surface, the material slowly swells up like a hollow foam, and this change in size is fatal to the normal service of the material.

In addition to irradiation swelling, neutron irradiation produces a large number of defects in the material, which will also affect the mechanical properties of the material, making the material hard, brittle, and more prone to breakage, thus affecting the safe operation of the fusion reactor.

Neutrons also undergo nuclear reactions with materials, changing the elemental composition of materials, for example, the metal W will become Re, Os, Hf, and Ta.

Over time, the composition of the material will become completely different from the beginning, which will have a great impact on the material.

Although the problem of neutron irradiation is also present in fission reactors, the neutrons of fission reactors are much lower than those of fusion reactors in terms of energy and flux, so the technology of fission reactor materials cannot be directly transplanted into fusion reactors.

And in terms of high-flux deuterium-tritium plasma bombardment.

The confinement of D-T plasma in fusion reactors is also not perfect, and a large number of D-T ions will blast into the first wall of material in the reactor. Because T fuel is very expensive, hundreds of millions of yuan per kilogram, it is recycled in fusion reactors through neutron and lithium reactions.

In order to prevent T from staying in the material, the first wall uses tungsten, which has the weakest affinity for hydrogen among the metals. After entering the tungsten, it is difficult to effectively combine with the material itself, so it has to run back out and continue to participate in fusion.

Although tungsten itself does not bind to T, the cavity created by neutron irradiation has a very strong attraction to T, and it is difficult for T to come out once it runs into the hole.

This causes the T fuel to remain inside the material, thus disrupting the T cycle above, making T less and less used.

Without T, fusion is naturally impossible.

In addition, as an isotope of the gas hydrogen, D-T forms gas molecules after entering the pores of the material. These gas molecules are squeezed into a confined space, creating very high pressures, which can squeeze out hydrogen bubbles and cause further cracking of the material, causing serious damage.

There is basically no D-T problem in fission reactors, and this problem is completely new for fusion reactor materials, and the research on this problem is still in the research stage.

Even the scientific phenomena of basic research have not yet been explained.

There is still a long way to go before commercial fusion reactor materials are developed, don't ask, ask about commercial 50 years from now.

There are other difficulties.

The service environment in a fusion reactor is extremely harsh, which means that it is very difficult to conduct related experiments.

For example.

Studying fusion reactor materials obviously requires neutron irradiation experiments, but neutron sources are scarce on this planet, and doing a neutron irradiation experiment is not only expensive, but can also take years to accumulate enough neutron damage.

There are only a handful of neutron irradiation data available in the current literature, which is obviously not conducive to the development of new materials.

Nowadays, the study of fusion neutron irradiation often uses ion irradiation as an analogy, but it is still very expensive!

Ions are also charged and have a shallow depth of penetration in the material, concentrated within a few microns of the material's surface, while neutrons are often able to penetrate the entire material, causing uniform irradiation damage.

Therefore, it is difficult to say how much of the results of ion irradiation can be used for neutron irradiation.

Another research idea is to use supercomputers to simulate the damage of neutron irradiation to materials directly in the virtual world, but this is also what many research institutes are doing.

But this idea also faces great challenges.

To build a model in a computer, the time scale spans femtoseconds to years, and the spatial scale ranges from angstromes to centimeters, with dozens of orders of magnitude difference in between.

No supercomputer can simulate this process accurately, and now the model can only be simplified with various 'spherical chickens in a vacuum'.

"What?, can you make time?" Professor Tian continued to encourage Mu Jingchi, "Your habit of coming home from work on time can be changed, and it's okay to go back two or three or four hours late." ”

Mu Jingchi shook his head, but still refused.

The first wall material is almost insoluble for the current Mujingchi.

In this high-energy environment, any material structure is broken, and if the current homogeneous material is not good, it is basically no problem. Materials science is originally about finding a way to find a way in the microstructure of materials, and this microstructure is broken, and no matter how awesome the process is, it is not easy to make it!

Even if Mu Jingchi gets the relevant knowledge of the future, there is no information about the commercial use of nuclear fusion.

Either there is no breakthrough in the future about nuclear fusion, or the knowledge extracted is limited and has not been included in the knowledge related to nuclear fusion.

From the current Mu Jingchi point of view, this problem cannot be solved by simple materials. It requires the cooperation of materials, mathematics, physics, computer science, and so on.

Whether it is a tokamak, a stellar pile, or a NIF with different principles, the fusion reactor of the three alpha energy cannot bypass this first wall.

"You'd better find another master!" Mu Jingchi shook his head, "I don't have the time and energy, and I don't have the ability to do this first wall material research. ”