Great Country Academician

Undecided, quantum mechanics, not enough brains, parallel universe.

This is a very popular sentence on the Internet, which means that when encountering unsolvable things or doubts, just say "quantum mechanics".

In the material world, there is actually a saying like this.

Not enough materials, graphene to make up.

Graphene is called "all-round material" by people in the material field.

It is a carbon material composed of carbon atoms tightly packed into a single layer of 'two-dimensional honeycomb lattice structure', which has excellent optical, electrical and mechanical properties. It has adaptability and important application prospects in almost most application fields such as materials science, micro-nano processing, energy, biomedicine, and drug delivery.

This is a popular material, and many ordinary people know it.

Of course, the powerful performance of graphene materials is also staggering.

Its strength and hardness even exceed that of diamonds, which can reach a hundred times that of high-quality steel. A one-centimeter-thick plate made of it can allow a five-ton adult elephant to stand firmly on it without collapsing and breaking.

For another example, in terms of light transmittance, the light transmittance of ordinary glass is only about 89%, while the light transmittance of graphene can reach 97.7%, so it is almost transparent to the naked eye.

And if graphene is used to make the battery screen of mobile phone and computer, the screen can be folded almost at will, even folded into tofu cubes and put in the pocket without affecting its performance.

In terms of electrical and thermal conductivity, there is no traditional material that can surpass graphene.

In addition, graphene materials are also a major direction in the field of superconducting research.

In 2018, Cao Yuan from the Massachusetts Institute of Technology in the United States and his mentor, MIT physicist Pablo Jarillo Herrero, published a paper in the journal Nature, showing that The team's research results on graphene.

When the overlapping rotation angle of two graphene sheets is close to 1.1°, the energy band structure will approach a zero-dispersion energy band, causing this energy band to transform into a Mott insulator when half-filled.

And this kind of superconductivity after rotating and charging the stacked graphene.

In addition, graphene has extremely high mobility of electrons, which makes it possible to realize pairwise pairing of electrons in superconductors, making it one of the future materials for studying high-temperature superconductivity, or even room-temperature superconductivity.

However, it is very difficult to break through room temperature superconductivity on graphene.

Even after more than ten years, Xu Chuan has never heard of any country that can manufacture graphene high-temperature superconducting materials. High-temperature graphene superconductivity is still being explored in the laboratory, let alone room temperature superconductivity.

Of course, the potential of graphene superconducting materials is enormous.

On the one hand, graphene, a two-dimensional material, can be fabricated arbitrarily like plasticine as long as a method is found. It can be round, square, long, flat, or hollow.

On the other hand, it lies in the current carrying capacity of the graphene material.

There is also a distinction between superconducting materials and superconducting materials.

The stronger the current carrying capacity, the stronger the magnetic field and various properties that can be provided.

In this regard, graphene has great potential.

The only reason for limiting the application of this superb material is that industrial production is too difficult.

At present, there is still no way to produce high-quality graphene in large quantities and stably.

But for now, what Xu Chuan wants is not the superconducting ability of graphene materials. He only needs the excellent physical properties of graphene to help improve the toughness of high-temperature copper-carbon-silver composite superconducting materials.

As for the current problem that graphene cannot be mass-produced, that is not a problem he needs to worry about.

If it is applied to superconducting materials, small batch manufacturing is also sufficient.

How to cut costs, how to produce products, and how to make profits from them are all things that need to be considered by the industry and business circles, and have nothing to do with him as a scholar.

Compared with the doped zirconia atoms mentioned by Academician Zhang Pingxiang, Xu Chuan is more optimistic about using graphene materials as whisker (fiber) toughening materials to make up for the toughness of high-temperature copper-carbon-silver composite materials.

Because for a superconducting material, if the crystal structure of the material is broken, it will lead to a gap in the superconducting energy gap, and a gap in the superconducting energy gap will lead to a sharp decrease in the superconducting performance in all aspects.

But the core of whisker (fiber) toughening technology is actually rooted in the chemical bonds of materials.

As we all know, most metal materials are prone to plastic deformation, the reason is that the metal bond has no directionality.

In materials such as ceramics, the bonding bonds between atoms are covalent bonds and ionic bonds, and the covalent bonds have obvious directionality and saturation.

In this case, when the ions of the same sign of the ionic bond approach, the repulsive force is very large, so the ceramics mainly composed of ionic crystals and covalent crystals have very few slip systems, and generally break before slipping occurs. (High school knowledge, stop saying you don’t understand!)

This is the root cause of the brittleness of ceramic materials at room temperature, and the properties of high-temperature copper-carbon-silver composite superconducting materials are very similar to ceramic materials.

However, the whisker (fiber) toughening technology can make up for this very well. When the whisker or fiber is pulled out and broken, a certain amount of energy is consumed, which is beneficial to prevent the expansion of cracks and improve the fracture toughness of the material.

To understand it simply, when you want to break a chopstick, there is a film on the chopstick, which can absorb the force from your arm, thus maintaining the shape of the inner chopstick.

Of course, the specifics of using graphene for whisker (fiber) toughening are more complex.

Because the combination of graphene and high-temperature copper-carbon-silver composite superconducting materials is not simply mixed together, it is more like a composite material that is organically combined through an extremely thin interface.

In this case, the chemical bonds in graphene may replace the doped carbon atoms in the copper-carbon-silver composite.

The reason why Xu Chuan chose to use graphene as a toughening material is also because of this consideration.

Graphene is a pure single-layer carbon material with a 'two-dimensional honeycomb lattice structure', and its organic combination with the copper-carbon-silver material interface will not change the composition of the high-temperature copper-carbon-silver composite superconducting material.

So in theory, it is still possible to toughen whiskers (fibers) through graphene.

As for whether it can be done specifically, it depends on the results of the experiment.

In the Chuanhai Materials Laboratory, Xu Chuan and Zhang Pingxiang started from various directions they were optimistic about, and studied to solve the problem of insufficient toughness of high-temperature copper-carbon-silver composite superconducting materials.

On the other side, Gao Hongming, who left to prepare the parameter information of the domestic controllable nuclear fusion experimental reactor, came back.

It not only brought detailed parameters of the experimental reactors in major domestic controllable nuclear fusion research institutes, but also brought a list of domestic manufacturers who are qualified and capable of producing high-temperature copper-carbon-silver composite superconducting materials.

What Xu Chuan looked at first was the detailed parameters of the experimental reactors in the major domestic controllable nuclear fusion research institutes.

This is related to the actual measurement of the plasma turbulence control model.

In the office, Xu Chuan flipped through the materials brought by Gao Hongming.

Calculating loosely, there are currently more than a dozen controllable nuclear fusion research institutes in China, but only eleven fusion reactors.

The number of these cans is indeed quite a lot, but in fact, most of the eleven fusion reactors are just experimental reactors or even device reactors.

The so-called experimental reactor refers to the experimental device that can meet the most basic experimental requirements of plasma experiments.

As for the device pile, let alone, it can't even do an ignition experiment.

According to the information brought by Gao Hongming, there are currently only two fusion reactors capable of conducting ignition and operation experiments in China.

They are the magnetic confinement fusion tokamak device 'EAST' of the Institute of Plasma Physics of the Academy of Sciences and the inertial confinement fusion device 'Shenguang' of the Ninth Academy of Engineering.

The method of inertial restraint is completely different from magnetic restraint.

Magnetic confinement can be understood as letting high-temperature plasma flow and fuse in the device to form high temperature.

The inertial confinement is to use the inertia of the material to pack a few milligrams of deuterium and tritium mixed gas or solid into a small ball with a diameter of about several millimeters.

The laser beam or particle beam is evenly injected from the outside, and the spherical surface evaporates outward due to energy absorption. Under its reaction, the inner layer of the spherical surface is squeezed inward to form a high-temperature environment, allowing the mixture of several milligrams of deuterium and tritium to explode. , generating a large amount of heat energy.

If such explosions occur three or four times per second and continue continuously, the energy released is equivalent to a million-kilowatt power station.

In simple terms, inertial confinement is similar to the explosion of a hydrogen bomb, and then absorbs thermal energy from the explosion energy to generate electricity.

It's just a smaller, more controllable kind.

This method is meaningless to the plasma turbulence control model studied by Xu Chuan, because the fusion methods are completely different.

So after excluding the inertial confinement fusion device "Shenguang" of the Ninth Academy of Engineering, the only experimental reactor he can choose is the "EAST" magnetic confinement fusion tokamak device.

The 'EAST' magnetic confinement fusion tokamak device, also known as the all-superconducting tokamak nuclear fusion experimental device, has created more than 50 million degrees and 100 million degrees Celsius plasma operation experiments in 16 and 18 years respectively.

In 2017, a record-breaking 101.2-second steady-state long-pulse high-constraint plasma operation was achieved.

In China, it is the well-deserved leader in the field of controllable nuclear fusion, even if it is placed in the world, it is also the top batch of experimental reactors.

However, apart from 'EAST', other fusion devices are somewhat unsatisfactory.

Xu Chuan did not expect that at the end of 2019, the field of controllable nuclear fusion in China would still be like this.

Indeed, from a technical point of view, on the route of controllable nuclear fusion, the country is already the top batch, and the technologies as a whole are quite good.

But in the experimental pile, it is indeed a little rare.

Except for the 'EAST' magnetic confinement fusion tokamak device, there are currently no other experimental reactors that can do ignition experiments.

The well-known KTX fusion reactor in the first ring of the University of Science and Technology, the Circulator No. 2 HL-2A and HL-2M experimental reactors and other equipment are basically still under construction at present.

Even Circulator No. 2, which has the latest completion time, will have to wait until the end of 20 years.

And even if it is completed, it will not be able to start the ignition test immediately. It will take at least one to two years to complete various tests, and it will be possible to test the plasma turbulence model after at least two and three rounds of ignition experiments.

This situation made Xu Chuan helplessly smile.

It now appears that he has no choice at all.

The only fortunate thing is that the parameters of the 'EAST' magnetic confinement fusion tokamak device are quite excellent.

The host part of the EAST device is 11 meters high, 8 meters in diameter, and weighs 400 tons. It is composed of six major components, including an ultra-high vacuum chamber, a longitudinal field coil, a poloidal field coil, an inner and outer cold shield, an outer vacuum Dewar, and a support system.

It has 16 large "D"-shaped superconducting longitudinal field magnets, which can generate a longitudinal field magnetic field strength of 3.5T; 12 large poloidal field superconducting magnets can provide a flux change ΔФ≥ 10 volts; through these poloidal field superconducting The magnet will be able to generate a plasma current ≥ 1 million amperes; the duration can reach more than 1000 seconds, and the temperature will exceed 100 million degrees under high-power heating

This series of parameters, even if it is placed in the world, is quite excellent.

Excellent equipment, coupled with the mathematical model of plasma turbulence, even if it is only a phenomenological model, Xu Chuan is confident that he will break the record for the longest operating time of the current tokamak device.

Even chasing stellarator run-time records is not out of the question.

After reading the information in hand, Xu Chuan shook his head lightly and sighed: "I never thought that the development of domestic controllable nuclear fusion would be like this."

On the sofa, Gao Hongming leaned forward and asked nervously, "Is there anything that meets the requirements?"

Xu Chuan nodded, shook his head again, and said, "There are some that meet the requirements, but there is only one. The EAST device on Luyang's side meets the requirements from the data. As for the others, none of them can."

Hearing this, Gao Hongming breathed a sigh of relief, and said with a smile: "As long as there is one that meets the requirements, it is fine. The leader of the EAST device is Academician Chen Mingji, and he is also the person in charge of our country's connection with the ITER international fusion project. I will go to communicate with Academician Chen."

Xu Chuan nodded, thought for a while and said, "I should have gone to this matter in person, but recently I am working with academician Zhang Pingxiang on how to optimize high-temperature copper-carbon-silver composite superconducting materials, and I really can't get away from it." .”

"Well, I asked Academician Peng Hongxi to go with you, and it seems to be more important. After all, to use other people's equipment, you need to modify the control model. It is also a big thing for controllable nuclear fusion. .”

Gao Hongming nodded with a smile, and said, "It's okay, you can do your research first, I believe Academician Chen will understand."

After a pause, he continued: "By the way, regarding the production of high-temperature copper-carbon-silver composite superconducting materials that you communicated with Mr. Qin before, I will also provide information on manufacturers who are qualified and capable of production. I brought it here by the way, would you like to take a look first?"

Xu Chuan nodded, took the information from Gao Hongming, and was about to read it, he thought for a while and then said: "By the way, I just read the information, the 'EAST' magnetic confinement fusion tokamak device still uses niobium Titanium alloys as superconducting materials."

"About this application for the 'EAST' magnetic confinement fusion tokamak device, you can communicate with Academician Chen. My side is not in vain, and I will make some compensation."

"If he is willing, I can provide him with some high-temperature superconducting materials for free in the first batch after the high-temperature copper-carbon-silver composite superconducting material is manufactured. I believe that the performance of the high-temperature copper-carbon-silver composite superconducting material can make The 'EAST' magnetic confinement fusion tokamak goes a step further."

PS: I brought the computer back this afternoon, but it’s too late. Let’s double update it tomorrow. By the way, ask for a monthly ticket (it’s about 500 yuan faster, woo woo ┗( T﹏T )┛,)