Chapter 400: Problems that can be solved with mathematics are not troubles
After Zhao Guanggui left, Xu Chuan returned his attention to his previous research on magnetic surface tearing, distortion modes, plasma magnetic islands and other issues.
I looked at the computer and saw that except for part of the data, most of the models that were previously running in the supercomputing center were still being processed.
Even with the assistance of supercomputer, it is not 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 briefly checking the operation of the model and confirming that there were no problems, Xu Chuan picked up the data that Zhao Guanggui had brought before on the table and read through it again.
He is very interested in this new material that has not yet been named.
After all, the value of a composite material that can withstand high temperatures of 3,500 degrees is quite astonishing.
Even if it may not necessarily be applied to the first wall material of controllable nuclear fusion, it still has sufficient value.
In addition to being commonly used as high-temperature refractory materials such as abrasives, 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 American space shuttle is a layer of high-temperature-resistant and insulating ceramic material.
Of course, the material in front of us will definitely not reach this level.
Because it has an important flaw, when most materials are carbon nanomaterials, its high temperature resistance properties can only withstand high temperatures in a vacuum environment, and the use conditions are quite harsh.
This is no problem for controllable nuclear fusion. After all, the reactor chamber itself is in a vacuum state after operation.
But for aerospace, the problem is huge.
After all, most areas of fighter jets, rockets, and space shuttles that require high-temperature-resistant materials are exposed to the air.
For example, aircraft engines, outer insulation materials of rockets and space shuttles.
Of course, if this new material is covered with a high-temperature-resistant and air-isolating coating, it should be able to be applied to engines.
It's just that the service life of the coating is generally a big problem, especially in places like 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.
But this is not an easy task. At least in a short period of time, he can't find any good inspiration or ideas from the data in front of him.
Of course, this is just a casual thing.
Rather than optimizing the high-temperature resistance of this new material in the air, what Xu Chuan wants to do more is to see if he can calculate through mathematics whether this new material can withstand neutron radiation.
It is not impossible to use mathematical tools and models to verify the radiation damage suffered by a material when irradiated with neutrons.
After all, it is too difficult to conduct a real neutron irradiation experiment.
Not to mention other countries, there are only a handful of places in China that have the ability and qualifications to conduct complete neutron irradiation experiments.
One is the Daya Bay nuclear fission power station, and the other is the spallation neutron source base in Dongguang.
The former uses neutrons emitted by nuclear fission itself to conduct irradiation experiments, while the latter uses a strong current proton accelerator to accelerate protons to hit tungsten, beryllium and other metals to create neutrons, and then conduct neutron irradiation tests.
But no matter which one it is, there is a considerable gap between the energy levels of neutrons produced by real deuterium and tritium fusion.
The fusion of each deuterium and tritium atomic nucleus will produce a 14.1 mev neutron. Although placed in the Large Strong Particle Collider, 14.1 mev is not a high energy level.
But to create such high-energy neutrons, there are almost no other ways except hydrogen bomb explosions and deuterium-tritium fusion.
This is one of the reasons why first wall materials are difficult to develop.
There was no way to conduct neutron irradiation experiments, but it was impossible not to develop the first wall material, so physicists, materials scientists, and programmers worked together to come up with a 'nuclear data processing program', which included 'China
Measurement of sub-irradiation effects.
In fact, the principle is very simple. It uses the neutron radiation 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 14.1 mev of energy, and how much damage they will cause to the target material can be speculated on.
After all, in the process of interaction between energy-carrying neutrons and target atoms, the neutron must first interact (i.e., collide) with a lattice atom, and then the energy-carrying neutron can transfer energy to the lattice atom, generating a kpa
Colliding atoms.
And whether this kpa collision atom will continue to leave the nucleus to collide with the next atom, and how much energy will be lost, these are all original records and can be speculated on.
It's just that 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 previously established for plasma turbulence, the first experiment only managed to achieve control for 45 minutes.
After obtaining accurate experimental data and making targeted adjustments and optimizations, the running time was pushed to more than two hours.
This shows 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, at least it is much better to use the phenomenological model to exclude some materials first and then conduct specific experiments than to do it directly.
After all, neutron irradiation resistance performance testing experiments are too precious and difficult to do, especially high-energy neutron irradiation experiments, which are even more difficult.
.......
After integrating the material data in his hand, Xu Chuan entered 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.
This chapter is not over yet, please click on the next page to continue reading! The only instability point lies in the unique arrangement of carbon nanotubes and hafnium crystal structures. There has been no relevant empirical data for this material in the past. Xu Chuan can only rely on
Let’s 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 pen in his hand stayed on "Avoid". After thinking for a while, he took action.
"Without considering the crystal effect and the potential between atoms, the calculation is based on classical mechanics. Suppose: the mass of the incident neutron is m1, the energy is eo; the mass of the target atom at rest is m2..."
"Then the dpa calculation formula can be expressed as dpa=(∫σpx(e)?(e)?Φe)?t(6), and obx(e) is the off-site cross-section of the incident particle with energy e, and t is the radiation
Lines of formulas were written out in Xu Chuan's hands. If the Lindhard-Robinson model was used to calculate dpa under neutron irradiation conditions, it would be enough for him to create a model and input data into it.
However, the unique arrangement of carbon nanotubes and hafnium crystals required him to re-consider some material variables, especially the speed of neutron absorption by hafnium, which required key calculations.
Instead of modifying the Lindhard-Robinson model and creating a new one, he might as well just start the calculation.
Anyway, this is not difficult.
At least, to him it is.
For him, any trouble that can be solved using mathematics is not a trouble.
...
I don't know how much time passed, but when Xu Chuan put down the black pen in his hand, there were rows of functions on a piece of paper specially used to list calculation result data.
【pa/s=2.718e-08】
【pm/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, Xu Chuan breathed a sigh of relief and couldn't help but shake his head.
Judging from the simulation calculation results, it is obvious that the performance of this new material is not excellent when faced with numerical calculations simulating neutron irradiation.
Not even as good as austenitic steel.
As for the key, it should lie in the additive hafnium oxide.
After all, for a material that is resistant to neutron radiation, not all of the incident particle energy transferred to the struck atoms will cause radiation damage to the material.
The energy of neutrons is transferred to the interior of the atom, causing ionization and electron excitation effects, but it does not last in the material. Only part of the energy is transferred to the nucleus, causing secondary dislocation and forming point defects. This part of the energy is called radiation damage energy.
.
To put it simply, it means that neutrons collide with material atoms. If the energy transferred to the lattice atom exceeds a certain minimum threshold energy, the atom will leave its normal position in the lattice, leaving a vacancy in the lattice.
Not to mention, the atoms that were knocked out will continue to form multiple collisions in the material.
Just like playing billiards, strong force works wonders. When you can hit the cue ball with unlimited force, the cue ball will transfer the force to other sub-balls.
And as long as these sub-balls run on the table for long enough, they will always fall into the pocket.
Of course, this is only theoretically feasible. In fact, billiard balls will stop for various reasons, or they will not fall into the pocket due to angle problems.
The same goes for neutrons. Xu Chuan wants these neutrons. The bagging is equivalent to the neutrons passing through the first wall material smoothly, and those with wrong angles will cause radiation damage.
The hafnium element has an extremely high absorption rate of neutrons. During this process, the initial value will increase significantly, which in turn will amplify 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 generally reflect the performance of the material in resisting neutron irradiation.
However, although the calculation results were terrible, Xu Chuan was not discouraged.
On the contrary, there was a hint of excitement in his eyes.
Because this calculation result confirmed his previous speculation.
Hafnium oxide does not work as an additive in materials, but what about zirconium oxide?
The chemical properties of zirconium are not much different from those of hafnium, but in terms of neutron absorption rate, they can be said to be two extremes.
Hafnium is extremely affinity to neutrons, and its absorption rate is more than five hundred times that of zirconium.
If zirconium oxide can replace hafnium oxide as an additive to reconstruct this new type of carbon composite material, maybe the first wall material will really be available.
Looking at the data on the manuscript paper, Xu Chuan's eyes were filled with excitement and joy.
Now, all we have to do is wait for Zhao Guanggui and the others to use zirconium oxide instead of hafnium oxide to synthesize the material again. I hope everything goes well.
