Chapter 399: Problems that Can Be Solved with Mathematics Are Not a Problem

After Zhao Guanggui left, Xu Chuan returned his attention to the previous research on magnetic surface tearing, distortion mode, plasma magnetic island and other issues.

He looked at the computer. The model that was previously running in the supercomputer center was still being processed except for a part of the data.

Even with the assistance of supercomputers, it is not so easy to simulate the magnetic surface tearing effect produced during the fusion process of high-temperature and high-density deuterium-tritium plasma flow.

After all, the amount of data is too large.

After a brief inspection of the operation of the model and confirming that there was no problem, Xu Chuan picked up the data that Zhao Guanggui had brought on the table and read it again.

He was quite interested in this new material that has not yet been named.

After all, a composite material that can withstand a high temperature of 3,500 degrees is of amazing value.

Even if it may not be used in the first wall material of controlled nuclear fusion, it still has enough value.

In addition to ordinary high-temperature refractory materials such as abrasives, casting molds, nozzles, heat-resistant bricks, etc., heat-resistant materials can also be used as structural components of top technologies such as fighter jets and rockets.

For example, the outermost material of the US space shuttle is a layer of high-temperature resistant and heat-insulating ceramic material.

Of course, the material in front of us will definitely not reach this level.

Because it has an important defect. When most materials are carbon nanomaterials, its high-temperature resistance can only withstand high temperatures in a vacuum environment, and the use conditions are quite harsh.

This is no problem for controlled nuclear fusion. After all, the reactor chamber itself is in a vacuum state after operation.

But for aerospace, the problem is very big.

After all, most fighter jets, rockets, and space shuttles need to use high-temperature resistant materials in areas exposed to the air.

For example, the outer insulation materials of aircraft engines, rockets and space shuttles.

Of course, if a layer of high-temperature resistant and air-insulating coating is covered on this new material, it should be applied to the engine.

However, the life of the coating is generally a big problem, especially in places such as fighter engines where the working environment is extremely harsh.

If the characteristics of this new material can be optimized, and the carbon material inside can be optimized so that it can withstand temperatures of more than 3,000 degrees in a conventional environment, then the value of this new material will be great.

However, this is not an easy task. At least in the short term, he can't find any good inspiration and ideas from the data in front of him.

Of course, this is just a side job.

Compared with optimizing the high temperature resistance of this new material in the air, Xu Chuan wants to see if he can use mathematics to calculate whether this new material can withstand neutron irradiation.

It is not impossible to verify the radiation damage of a material to neutron irradiation through mathematical tools and models.

After all, it is too difficult to do neutron irradiation experiments with real swords and guns.

Let alone other countries, there are only a few places in China that have the ability and qualifications to do complete neutron irradiation experiments.

One is the Daya Bay Nuclear Fission Power Station, and the other is the Spallation Neutron Source Base in Dongguan.

The former uses neutrons emitted by nuclear fission itself to conduct irradiation experiments, while the latter uses a high-current proton accelerator to accelerate protons to hit metals such as tungsten and beryllium to produce neutrons, and then conduct neutron irradiation tests.

But no matter which one, the energy level is quite different from the neutrons produced by real deuterium-tritium fusion.

Each deuterium-tritium nucleus fusion will produce a 14.1 MeV neutron, although 14.1Mev is not a very high energy level in a large particle collider.

But to produce such a high-energy neutron, there is almost no other way except hydrogen bomb explosion and deuterium-tritium fusion.

This is also one of the reasons why the first wall material is difficult to develop.

There is no way to do neutron irradiation experiments, but the first wall material cannot not be developed, so physicists, materials scientists, and programmers have come up with a "nuclear data processing program", which includes the measurement of "neutron irradiation effect".

In fact, the principle is very simple. It uses the neutron irradiation damage mechanism to make a phenomenological or big data prediction of the collision between the neutron beam and the target material.

Because different neutrons carry different energies, for example, high-energy neutrons in the deuterium-tritium fusion process will carry 14.1Mev of energy, and how much damage will be caused to the target material, these can be speculated.

After all, in the process of interaction between the energetic neutron and the target atom, the neutron must first interact with a lattice atom (i.e., collide), and then the energetic neutron can transfer energy to this lattice atom to produce a KPA collision atom.

And whether this KPA collision atom will continue to leave the nucleus and collide with the next atom, and how much energy will be lost, these are all original records and can be further speculated.

However, this simulation method itself is phenomenological, and the simulated data is more or less "a little bit" unreliable.

Referring to the phenomenological mathematical model he established for plasma turbulence before, the first experiment only managed to control for 45 minutes.

After obtaining accurate experimental data, after targeted adjustments and optimizations, the running time was pushed to more than two hours.

From this, it can be seen how unreliable the phenomenological model is.

But in terms of neutron irradiation experiments, there is no other way.

Although the results obtained by simulation are not necessarily reliable. But at least, it is much better to use the phenomenological model to exclude some materials first, and then do specific experiments than to do it directly.

After all, the neutron irradiation resistance test experiment is too precious and difficult to do, especially the high-energy neutron irradiation experiment, which is even more difficult.

After integrating the material data in his hand, Xu Chuan input it into the computer.

Although the material is newly developed, elements such as carbon, silicon carbide, and hafnium oxide are all conventional substances in neutron irradiation experiments.

The only unstable point lies in the uniquely arranged carbon nanotube hafnium crystal structure. There is no relevant empirical data for this material in the past. Xu Chuan can only make a guess based on the conventional irradiation test data in the data.

After thinking for a while, Xu Chuan pulled out a stack of A4 paper from the drawer.

The black signature pen in his hand stopped at avoidance. After thinking for a while, he started.

"Without considering the crystal effect and the potential between atoms, calculate according to classical mechanics. Assume: the mass of the incident neutron is M1, the energy is Eo; the mass of the stationary target atom is M2"

"Then the DPA calculation formula can be expressed as DPA=(∫σpx(E)(E)ΦE)t（6）, and obx(E) is the off-position cross section of the incident particle with energy E, and t is the irradiation time."

"Derived: σpx(E)= 2∑i∫Tmax、Td·vd(T).dσd(T，E)/dT·DT"

"Vd（T）=（0.8/2Td）·Tdam"

Xu Chuan wrote out a line of formulas. If he used the Lindhard-Robinson model to calculate the DPA under neutron irradiation conditions, he would just make a model and input the data into it.

However, the unique arrangement of carbon nanotube·hafnium crystals required him to reconsider some material variables, especially the speed of hafnium's neutron absorption rate, which was something that needed to be calculated.

Instead of modifying the Lindhard-Robinson model and creating a new one, he might as well just do the calculation.

Anyway, this is not a difficult task.

At least, it is for him.

For him, any problem that can be solved by mathematics is not a problem.

I don’t know how long it has been. When Xu Chuan put down the black signature pen in his hand, there were rows of functions on a manuscript paper specially used to list the calculation results.

[PWR·DPA, dpa/s=2.718E-08]

[PWR·He, appm/s=6.172E-09]

[HTTR·DPA, dpa/s=2.602E-09]

[HTTR·He]

Picking up the manuscript paper on the table and looking at the results on it, Xu Chuan breathed a sigh of relief and couldn’t help shaking his head.

From the simulation results, it is obvious that this new material does not perform well in the numerical calculation of simulated neutron irradiation.

Even worse than austenitic steel.

As for the key, it should be the additive hafnium oxide.

After all, for a neutron-resistant material, not all incident particle energy transferred to the struck atom will cause radiation damage to the material.

The energy of the neutron is transferred to the inside of the atom, causing ionization and electron excitation effects, but it will not last in the material. Only part of the energy is transferred to the nucleus, resulting in secondary dislocation and forming point defects. This part of energy is called radiation damage energy.

Simply put, when a neutron collides with a material atom, if the energy transferred to the lattice point atom exceeds a certain minimum threshold energy, the atom will leave its normal position in the lattice, leaving a vacancy in the lattice, and the atom that is knocked out will continue to form multiple collisions in the material.

Just like playing billiards, great force can make miracles. When you can use infinite force to hit the mother ball, the mother ball will transfer the force to other balls.

And as long as these balls run on the table for a long enough time, there will always be a time to fall into the pocket.

Of course, this is only theoretical feasibility. In fact, billiards will stop for various reasons, or they will not fall into the pocket due to angle problems.

The same is true for neutrons. Xu Chuan wants these neutrons to fall into the bag, which is equivalent to the neutrons passing through this first wall material smoothly, while those at the wrong angle will cause radiation damage.

The absorption rate of hafnium to neutrons is extremely high. In this process, the initial value will increase significantly, which will lead to the amplification of the damage caused by the neutron irradiation effect.

This is a fatal flaw for the first wall material.

Although the data calculated by the Lindhard-Robinson calculation formula is phenomenological, it can also roughly reflect the performance of the material in terms of neutron resistance.

However, although the calculation result is very bad, Xu Chuan is not discouraged.

On the contrary, there is a hint of excitement in his eyes.

Because this calculation result confirms his previous speculation.

Hafnium oxide does not work as an additive in the material, so what about zirconium oxide?

Zirconium is not much different from hafnium in chemical properties, but in terms of neutron absorption rate, it can be said to be two extremes.

Hafnium is extremely affinity with neutrons, and its absorption rate is more than 500 times that of zirconium.

If zirconium oxide can replace hafnium oxide as an additive to reconstruct this new type of carbon composite material, perhaps the first wall material will really be found.

Looking at the data on the manuscript, Xu Chuan's eyes were filled with joy and excitement.

Now, we just have to wait for Zhao Guanggui and his team to use zirconium oxide to replace hafnium oxide and synthesize the material again. I hope everything goes well.

PS: There will be another chapter later