Xianlin Campus, in the Industrial Building.

The second time I came here, this time Xu Chuan deliberately observed the office situation in the building.

Two months have passed, and under the leadership of Academician Peng Hongxi, the work of personnel recruitment and project research has been in full swing.

Along the way, he saw several different groups of researchers gathered in different places to discuss something.

Of course, he didn't look closely.

As the general manager, he only needs to control the direction of the project and solve the most difficult problems.

As for the other issues, someone has to work on them.

He is just a person, not a god, and it is impossible to do everything in a super project like controlled nuclear fusion.

All the way to Peng Hongxi's office, Xu Chuan knocked on the open door.

Inside, Peng Hongxi was sitting at his desk dealing with work, and when he heard a knock on the door, he looked up, and then a smile appeared on his face.

Putting down the pen in his hand, he got up with a smile and greeted: "Academician Xu is here." Congratulations, you have broken another record and achieved the title of academician of the Chinese Academy of Sciences and the Chinese Academy of Sciences in one day. ”

Xu Chuan smiled: "Mrs. Peng is polite, in front of you, I am just a junior." ”

Peng Hongxi said with a smile: "The master comes first, your knowledge and ability have far surpassed our group of old men." ”

After a pleasant greeting, Xu Chuan cut to the chase and said, "Don't talk about this, I don't have much time to come over this time, there are still many other things to be busy, and Peng Laoling must have a lot of things on his hands." ”

"What about the plasma turbulence control model? Take me to see it. If there is no problem, I have to verify the application supercomputer above, and there are still a lot of things to be done. ”

Peng Hongxi nodded, got up and said, "Come with me, the model optimization has been done almost the same, but I don't know if it meets your requirements." ”

Xu Chuan: "Let's take a look first, and then change it if it doesn't work." ”

"For controlled nuclear fusion, the control of plasma turbulence in the chamber is a big deal, and it has to be done in a hurry."

Following Peng Hongxi, the two went all the way to the seventh floor.

"Zhou Ji, Xia Guang, you two come here."

Peng Hongxi shouted to the crowd in the office who were busy in front of the computer, and soon two middle-aged men stood up and walked over quickly.

Immediately, he Xu Chuan introduced: "In this office on the seventh floor are the researchers in mathematical and physical models that you specially arranged to recruit before, all of them are here, a total of twelve people. ”

"For the first two months, they have been working with the plasma professor to optimize the model."

"Zhou Ji and Xia Guanghe are the current person in charge, one is the other."

"Director Zhou Jizhou was originally an elite of the Chinese Academy of Sciences, mainly in plasma modeling."

"Xia Guang graduated from China University of Science and Technology, and has been working in fluid mechanics at the Sichuan Aerospace Bureau."

"Both have more than a decade of experience working in fluid mechanics and modeling."

After briefly introducing Xu Chuan, Peng Hongxi turned his head to look at Zhou Ji and Xia Guang, and then said: "This is the general person in charge of our controllable nuclear fusion project, Academician Xu Chuan Xu." ”

Hearing this, Zhou Ji stepped forward with a smile and said, "Academician Xu's famous name has long been heard of, and I have always wanted to meet him, and today I finally waited for the opportunity." ”

On the side, Xia Guang's personality was a little more restrained, but he just smiled and came up and shook his hand and said hello.

Xu Chuan shook hands with the two with a smile and said hello: "I've worked hard for you this time, take me to see the optimized model." ”

Zhou Ji nodded and said, "Okay, let's find a conference room, it's not easy to demonstrate here." ”

In the conference room, Xia Guang inserted the USB flash drive in his hand into the computer and connected it to the projection equipment.

Xu Chuan examines the work they've done these days.

【Application Chain Rules--Optimization √】

Neural Network Differentiation of Spatiotemporal Coordinates: Optimization √

【Multi-field Turbulence Model Constraints--Optimization √】

【Characterization of electric field fluctuations at turbulent edges--Optimized √】

【. 】

In Xu Chuan's eyes, the optimization catalog of an item is not only marked as completed, but also the performance effect tested after optimization, as well as the comparison with the previous data.

Although the supercomputing center of NTU cannot run the entire mathematical model completely, there is no problem in optimizing and testing some modules in the model individually.

To be honest, it is quite difficult to optimize the test data of the numerical control model of plasma turbulence.

However, Zhou Ji and Xia Guang are worthy of being the top talents from the Chinese Academy of Sciences and the Space Bureau, not only those places that he marked that need to be optimized have all been completed.

It's the places he didn't pay attention to and mark later, even if it was just a little bit of performance, and he also dealt with and rectified it.

After testing the relevant data, Xu Chuan nodded with satisfaction.

"Looking at the data, the optimization work is doing quite well. Compile a copy of the optimized model for me, and I'll go to a supercomputer to verify it. ”

I have to say that more people is more power.

If these things were all up to him, he wouldn't have been able to finish them in half a year. Again, this is based on his considerable familiarity with the model.

With the model, Xu Chuan and Peng Hongxi left the seventh floor.

Walking on the road, Peng Hongxi asked, "Your model should be just a model of the image at present, right?" How are you going to solve the problem of accurate detection of ultra-high temperature plasma in the chamber of a controlled nuclear fusion reactor? ”

"If you can't accurately detect the data of these plasmas, I'm afraid your model won't be able to be used on the reactor."

The detection of ultra-high temperature plasma turbulence in controlled nuclear fusion reactors is a major problem in the current controlled nuclear fusion technology.

Strictly speaking, it's just part of the puzzle of controlling 'UHT, high-pressure plasma turbulence' in the chamber of a fusion reactor.

Controlling plasma turbulence in controlled fusion reactors is a crucial step in this path of controlled fusion research.

But it's not just a problem, it's a series of problems.

A series of problems such as the control of the strong magnetic field generated by the external superconducting coil, the adjustment of the plasma turbulence by building a mathematical model, and the cooling system of the outer ring of the first wall are actually included.

It's just that at the moment, whether it's inertial constraints, magnetic constraints, or tokamaks and stellarators, there is no one path that can solve this problem.

Hearing this question, Xu Chuan smiled and said, "This question is complicated and complicated, but it is difficult to say, and it may not be very difficult. ”

Hearing this, Peng Hongxi asked with some curiosity: "How are you going to solve it?" ”

Currently, there are two common types of plasma turbulence measurements in the reactor chamber.

The first method is to measure the electromagnetic waves emitted by the plasma itself to obtain information about the plasma parameters, etc. The second is probe measurement, which is one of the basic means of plasma diagnosis by placing a solid probe into the plasma to obtain the required parameters.

These two methods are currently the most commonly used, but they both have their own drawbacks.

The disadvantage of the first method is that the spectrum of electromagnetic waves emitted by ions is very wide, the information contained is quite messy, and the image-only model built can only be accurate in a limited range.

Although the second probe method can obtain information about the fine structure of the plasma and the distribution of various parameters, it has the disadvantage of interfering with the measured plasma.

For example, changing the flow image, forming a space charge sheath, generating impurity pollution, etc.

After all, the plasma in the chamber of a fusion reactor is operating at ultra-high temperatures and pressures, and any small disturbance can cause the entire fluid operation to collapse. This in turn causes the ions to ram into the first wall.

Xu Chuan shook the hard drive in his hand with a smile and said, "Actually, the answer to this question is already hidden in the mathematical model I have established. ”

Hearing this, Peng Hongxi looked puzzled.

To be honest, he also knew about the model, but he didn't find anything hidden inside.

Xu Chuan smiled and said, "The current mathematical model I have at hand is actually based on the data from the previous PPPL laboratory in Princeton. ”

"The biggest disadvantage of the image-only model is that it is not accurate enough, but the biggest advantage is that the logic is simple and can be built in the absence of original data."

"And how the data from the PPPL plasma laboratory is observed, I think you should be clear."

Peng Hongxi thought for a moment and said: "If I remember correctly, the observation of high-temperature and high-pressure plasma at the PPPL Plasma Laboratory in Princeton uses the microwave detection method, which uses the principle of microwave interaction and plasma in the electromagnetic wave spectrum to measure plasma parameters. ”

"Are you going to use this method for the same measurements? However, the data obtained in this method is also not accurate. Because the amount of information obtained is too large, it is difficult to analyze it accurately, and only approximate image data can be obtained. ”

Xu Chuan said with a smile: "That's right, the data obtained from the detection of deuterium-tritium plasma in the reactor chamber is indeed huge, and it is difficult to analyze. ”

"But why do you have to look at the deuterium-tritium plasma itself?"

Hearing this, Peng Hongxi was stunned again, not observing the plasma itself? So what to observe?

Xu Chuan smiled and said, "Observe the data of 'impurities'!" ”

After a pause, he went on to explain: "At present, the mainstream of controlled nuclear fusion we are studying is DT controlled nuclear fusion, and we are also taking this road now, and the raw materials of DT fusion are deuterium and tritium, and the product of fusion is helium atoms + neutrons. ”

"The neutrons are reused for tritium multiplication reactions, and the helium atoms are taken away by the deflector."

"In this case, why can't we mix some helium atoms into the two raw materials of deuterium and tritium as the original 'impurities'?"

"The helium impurities that are incorporated into the feedstock will run in the reactor chamber along with the deuterium-tritium feedstock, and of course, it will end up in the deflector and sent away with the helium ash."

"But in operation, it produces electromagnetic radiation and microwave data that are quite different from deuterium-tritium plasma."

"The amount of information produced by helium impurities is undoubtedly much smaller than that produced by the large deuterium-tritium feedstock itself, but by observing the data of helium impurities, the plasma turbulence in the entire fusion reactor can be deduced."

"As a result, the data we get is relatively accurate."

Xu Chuan explained, Peng Hongxi thought about it for a while, and suddenly understood, with a hint of excitement in his eyes, he took over the topic and continued:

"The most important thing is that helium itself is a product of deuterium-tritium fusion, and it will not participate in deuterium-tritium fusion, because if you want to fuse helium atoms, the temperature must reach at least a billion degrees Celsius."

"In this way, it does not interfere with the fusion reaction of the deuterium-tritium plasma, which does not reach this temperature."

"And because with the addition of fuel, as the deflector is removed, it can monitor the movement of the entire plasma turbulence almost the entire time."

"The only drawback is that it is very troublesome to accurately analyze the information transmitted back by these helium atoms, and it can not be processed like the information of deuterium-tritium plasma."

"But it's not that hard for you."

"Because you've solved the NS equation, you have the ability and even the ability to do a mathematical model of the plasma turbulence in the reactor chamber for predictive control."

"As for the amount of computing, it is a supercomputing thing, as long as the performance of supercomputing is sufficient, then these troubles can be solved!"

After muttering this, Peng Hongxi raised his head and looked at Xu Chuan, his eyes shining with excitement.

To be honest, it is not the first time that electromagnetic waves that collect impurities by adding impurities to deuterium-tritium fuel can accurately determine the state of plasma turbulence.

But before, no one could do that.

Without him, because it can't be calculated at all.

Even if someone could make a mathematical model of it, it would not be possible to control the turbulent motion of the plasma for a long time.

Because fluid systems are chaotic and extremely sensitive to initial values, you can't give precise initial values for the flow in reality, and small perturbations are inevitable, which can be amplified to the point of unpredictable results.

In the past, the turbulent movement of plasma could be described as a completely chaotic system, and no one knew what it would turn out over time.

And the reason why it is feasible now is because the person in front of him has already figured out the theoretical foundation.

He solved the NS equation and used the results to make a mathematical model, and with this foundation, the calculation can be completed through this method.

That's the benefit of theory first.

This top-notch cutting-edge theoretical breakthrough and the development of science and technology driven by this kind of top-level cutting-edge are vividly reflected at this moment.

What's more, this is only part of the story, and it can even be said that it is a drop in the bucket. More advances in the field of fluid mechanics will emerge over time.

Various fields involving fluid mechanics, including aerospace, aerodynamics, weapons and equipment, will usher in leaps and bounds with the decipherment of the NS equation.

Just as the one who made the country hold the sword in his hand back then, this one also has the ability to lead a field or even a country forward.

After staring at Xu Chuan for a while, Peng Hongxi suddenly sighed softly: "How fortunate the country is to have you!" ”

(End of chapter)