With that sketch, Chief Engineer Wang left the STAR Stellarum Research Institute, returned to the headquarters of the Nuclear Industry Group in Shangjing on the same day, and contacted experts in the field of magnetofluid power generation in the engineering institute to discuss the feasibility of the application of magnetofluid power generation technology in controlled fusion devices.

However, although the team was gone, the working group of the nuclear industry group remained here in Jinling, and continued to communicate with the researchers of the STAR Stellarmient Research Institute on technical issues.

At the same time, the experiments of the STAR device did not stop there.

After receiving sufficient funding, the institute was almost extravagant enough to conduct experiments every three days, using hydrogen and helium as research objects, to observe the various complex physical properties of plasma in the stellarizer.

In order to collect valuable data, Lu Zhou even ordered the injection of 1mg of the precious deuterium/tritium mixture into the reaction chamber, risking damage to the first wall material to conduct a pilot fire.

In fact, the experiment did cause some damage to the STAR device, but fortunately, the damage was still repairable. However, even so, the entire unit must not be shut down for maintenance.

Of course, although it is expensive, the rewards are also quite substantial.

Not only did they verify the feasibility of the idea to ignite the fusion reaction, but they also obtained a thin slice of lithium bombarded by a neutron beam carrying 14 MeV of energy.

The latter, in particular, cannot be converted into money.

In China, they are probably the only ones who can do such extravagant experiments.

At this moment, this hard-won lithium metal sheet is lying quietly in a specially treated oxygen-free slide, which is placed under the scanning electron microscope by the staff wearing protective clothing.

In the laboratory outside the isolation room, Lu Zhou and other researchers standing in front of the computer saw the data and pictures collected from the scanning electron microscope on the screen.

As they expected, the originally regular metal surface is now full of holes.

Through the detection of infrared spectrometer, even traces of helium and tritium can be observed in the crooked pores.

Happily, this shows that the neutron beam carrying 14 MeV energy did react with 63Li, and they successfully recovered some of the tritium in the experiment.

As for the frustration......

There are so many problems they face that they can't finish in a few words.

Looking at the image on the computer screen, Professor Li Changxia sighed softly.

"I bet this thing will shatter if you touch it."

"Don't bet that even if it hasn't been bombarded by neutron beams, this thing isn't that strong." Staring intently at the hard-won data on the computer screen, Lu Zhou said casually.

Sheng Xianfu shook his head: "It's not just a matter of radiation damage, but the tritium production multiplication ratio is too low." And the most critical issue is not the recycling itself. The energy carried by the neutron beam is too high, and it often does not react with 63Li on the surface, but runs around inside the cladding material, and even if the tritium we need is generated, it is left inside the material and cannot be released at all. ”

The neutron carrying 14 Mev of energy is like a cannonball, and all metal bonds in front of it are as fragile as toys.

Moreover, the neutrons penetrating the first wall are not just as simple as punching a hole in the first wall, it will form a cavity in the inside of the first wall material like blowing a balloon, and eventually lead to the swelling, embrittlement, and even the peeling off of the surface material of the first wall material, thus causing serious accidents.

And this is one of the main reasons why the cladding material of fission reactors cannot be directly used in fusion reactors.

The two materials are two orders of magnitude different in terms of the standard of resistance to radiation damage.

Until now, their research had gone into uncharted territory, which meant that there was no more experience to draw on. What to do next, how to solve these problems, it is up to them to think about it.

After thinking for a moment, Professor Li Changxia tried to propose: "How about switching to molybdenum for structural materials?" ”

"Molybdenum can't do it," Lu Zhou shook his head and said, "Molybdenum has good heat resistance, but it will transmute into radioactive elements under neutron irradiation." ”

Another researcher went on to suggest, "What about tungsten? Tungsten has good heat resistance, and the transmutation products are osmium and rhenium, and there is no radioactivity problem! ”

This time, there was no need for Lu Zhou to speak, Professor Li Changxia shook his head, "It's a cliché." The heat resistance of tungsten is fine, but the plasticity is too poor. Thermal stress can cause cracks on the surface of the material...... When I was a visiting student in the DIII-D lab, there was a special talk about this issue. In short, it is impossible to use tungsten. ”

There was silence in the lab again.

At this time, Lu Zhou, who had been staring intently at the data on the screen, suddenly spoke.

"If we can't keep the neutron bundles inside, why don't we consider putting them in?"

"Let it go?" Sheng Xianfu was slightly stunned, then shook his head with a smile, "How can we recover the neutrons produced by the reaction after we let it go?" ”

The recovery of neutrons produced in DT fusion reactions is a key part of the entire nuclear fusion reactor technology, after all, the price of tritium resources is tens of thousands of times that of deuterium, not only in terms of grams, but also in terms of the cost of one gram is as high as 30,000 US dollars (17 years of data).

If the neutrons generated by the reaction cannot be recovered, it will not only cause a large amount of energy loss, but also cause the reactor to "shut down" due to tritium loss.

In an ideal fusion reactor, both tritium and neutrons should be preserved as intermediates, and the only waste produced is helium and heat.

Therefore, it is impossible to let the neutron go, and you have to leave it behind.

Hearing Sheng Xianfu's rhetorical question, Lu Zhou smiled faintly and continued.

"Letting them go is not the same as letting them go. Theoretically, no matter how we design the structure of the first wall, we cannot avoid the destruction of metal bonds by neutron beams. However, the self-healing ability of the metal is too poor, and there is a transmutation problem that is difficult to solve. ”

"So why not set up the first wall to be a self-healing material that allows neutrons to pass through, and then recover neutrons in liquid 63 lithium behind the first wall. As for the other side of 63 lithium, it is coated with a layer of beryllium metal, which is used to reflect neutrons that penetrate the liquid lithium layer without reacting. ”

This design is equivalent to sandwiching liquid lithium between the first wall and beryllium.

Sheng Xianfu lowered his head and thought for a while, feeling that this method seemed to be feasible, but he always felt that there was a problem everywhere.

After thinking for a while, he picked out the two most obvious questions he could think of.

"But where do you find the kind of material that allows neutrons to pass through and has a strong self-healing ability? Even after moving lithium to the first wall material, we still can't solve the damage caused by neutron radiation to the structural material. And, as you said, how do we get tritium back into the reactor from behind the first wall? ”

Hearing these two questions, Lu Zhou smiled faintly and said: "The second problem is actually not difficult to solve, at the working temperature of liquid lithium, both tritium and helium exist in gaseous form, and the two are incomprehensible to each other. ”

"We only need to apply a weak upward force to the entire liquid lithium neutron recovery system to transport the generated tritin above the entire system."

"Then, we just need to recover the exhaust 'gas' above the entire system."

The resulting tritium and helium as exhaust gas are re-injected into the reaction chamber for heating ionization. As for how to get helium out of the reactor, that's where the deflector works.

As for whether to choose a water-cooled deflector or a tungsten copper deflector or other deflectors, it is good to choose according to the specific needs at that time. This part of the technology, although critical, is not an unsolvable difficulty.

Speaking of this, Lu Zhou paused and continued, "As for the first question you mentioned, such a material cannot be found in alloys. So, let's just get rid of the metal entirely! ”

The moment he heard this, not only Sheng Xianfu, who raised the question, but also Professor Li Changxia, everyone in the laboratory was stunned.

Ditch the metal?

This......

That's a bit too edgy, right?

"Metal for structural materials?" Professor Li Changxia looked at Lu Zhou in surprise, "What is that for?" ”

Is it made of ceramic?

Although some research institutes have tried this, and the effect is okay, but the fatal thing is that the thermal conductivity of ceramics is too poor.

If you can't get the heat generated away from the reactor, you'll end up with problems.

"With carbon," after a pause, Lu Zhou said in an affirmative tone, "Or more accurately, with carbon fiber composites!" ”

This was not a whim that Lu Zhou had come up with, he had been thinking about it for a long time before that, and he had even thought about it when he had a casual conversation with Professor Kreber at the Spiral Stone 7-X Research Institute.

The carbon nucleus is relatively stable, not easy to react with neutrons, and can play a certain role in buffering the neutron beam, so that when the neutron beam comes into contact with the liquid lithium layer, most of the neutron beams will not directly break it down.

The part of the energy that is reduced by the carbon fiber layer will be released in the form of heat energy, and with its good thermal conductivity, the heat generated inside the reactor can be easily exported.

As for heat resistance, it's perfectly fine.

When not in contact with air and oxidizing agent, the carbon fiber material can withstand high temperatures of more than 3000 degrees, which is comparable to the melting point of tungsten, and fully meets the needs of the first wall material!

Glancing around at the people in the laboratory, Lu Zhou said: "The low-activation metal material is completely eliminated from the first wall, and carbon fiber is used as the first wall material and the main structural material, and the middle layer is filled with liquid lithium, and the outer layer is coated with beryllium to reflect neutrons. The shield is made of a mixture of paraffin and water and boron carbide and is clad in nuclear cement. In this way, we have every hope of solving the problem of tritium retention! ”

As for what kind of carbon fiber composite materials to choose and how to solve the self-healing problem of carbon fiber composite materials, this topic will be studied by the Materials Research Institute of Jinling Institute for Advanced Study.

Although the problem is serious, there is hope that Lu Zhou will solve it!

Professor Li Changxia couldn't help but say: "This is too ......"

What he wanted to say was that it was too unbelievable.

But this sentence was only halfway through when he was interrupted by Sheng Xianfu.

"No, I can't tell...... There's hope for that! ”

Interrupting Professor Li's words, Sheng Xianfu kept rubbing his chin with his index finger, and the look in his eyes became brighter and brighter.

"I have consulted the relevant literature, and the use of carbon fiber to replace part of the austenitic steel and tungsten steel structure is a technical route that is as promising as nano ceramics in the field of international controllable fusion!"

"However, carbon fiber composite materials are used to completely replace metal materials as the main body of structural materials, and the decelerated neutron beam is placed on the outside of the cladding material to react with the liquid lithium, and then the tritium in the liquid lithium is recovered through transportation...... This is the first time I've heard of this. ”

This is probably not a small difficulty, and it is not only a problem of carbon fiber composites themselves. For example, in the control of temperature. The carbon fiber material of the first wall works at a temperature of about 3000 degrees, while the boiling point of lithium metal is only 1340 degrees.

If the heat cannot be taken away in time, there is a risk that the liquid lithium in the entire "liquid lithium neutron recovery system" will be vaporized, which can be involved in the reactor along with the tritium-helium mixture produced by the reaction, or may even blow up the entire reactor......

There is also the problem of volume changes caused by the solidification of liquid lithium during shutdown......

But as Lu Zhou said, this line of thinking seems to work.

At least, it's worth a try!

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(I went out to collect materials yesterday,)

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