Chapter 351: Not enough material, graphene comes in!
Undecided when faced with problems, quantum mechanics, insufficient imagination, parallel universes.
This is a very popular saying on the Internet. It means that when you encounter something or a question that cannot be solved, just say "quantum mechanics".
In the material world, there is actually a saying like this.
If the material is not enough, graphene will make up for it.
Graphene is called an ‘all-purpose material’ by people in the materials industry.
It is a carbon material composed of carbon atoms tightly packed into a single layer of 'two-dimensional honeycomb lattice structure'. It has excellent optical, electrical, and mechanical properties. It is widely used in materials science, micro-nano processing, energy, biomedicine, and medicine.
Almost most application fields such as transmission have adaptability and important application prospects.
This is a popular material that many ordinary people know about.
Of course, the performance of graphene materials is also staggering.
Its strength and hardness even exceed that of diamond, and can reach a hundred times that of high-quality steel. A one-centimetre-thick plate made of it can allow a five-ton adult elephant to stand firmly on it without collapsing or 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 phones and computers, the screen can be folded almost at will, or even folded into tofu cubes and put in your pocket without affecting its performance.
In terms of electrical and thermal conductivity, there is currently no traditional material that can surpass graphene.
In addition, graphene materials are also currently a major direction in the field of superconducting research.
In 2018, researchers represented by Cao Yuan from MIT in the United States and his mentor, MIT physicist Pablo Jarillo Herrero published a paper in Nature magazine, showing
The team’s research results on graphene.
When the overlap angle of two sheets of graphene is close to 1.1°, the energy band structure will be close to a zero-dispersion energy band, causing this energy band to transform into a Mott insulator when half-filled.
This kind of superconductivity results from rotating and charging the stacked graphene.
In addition, graphene has extremely high mobility of electrons, making it possible to pair electrons in pairs like a superconductor, making it one of the future materials for studying high-temperature superconductivity and even room-temperature superconductivity.
However, it is very difficult to break through room-temperature superconductivity on graphene.
Even more than ten years later, Xu Chuan has not heard of any country that can produce graphene high-temperature superconducting materials. High-temperature graphene superconductivity is still under laboratory exploration, let alone room-temperature superconductivity.
Of course, the potential of graphene superconducting materials is huge.
On the one hand, graphene is a two-dimensional material. As long as a method is found, it can be fabricated at will like plasticine. 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 difference between superconducting materials and superconducting materials.
The stronger the current load capacity, the stronger the magnetic field and various performances it can provide.
In this regard, graphene has huge potential.
The only reason limiting the application of this excellent material is that industrial production is too difficult.
At present, there is 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 of graphene being unable to be mass-produced, that is not a problem that he needs to worry about.
If it is applied to superconducting materials, small batch manufacturing is also sufficient.
How to cut costs, how to productize it, and how to make profits from it are all things that the industry and business community need to consider, and they have nothing to do with him as a scholar.
Compared with the doping of zirconium oxide atoms mentioned by Academician Zhang Pingxiang, Xu Chuan is more optimistic about using graphene material as a whisker (fiber) toughening material to compensate for the toughness of high-temperature copper-carbon-silver composite materials.
Because for a superconducting material, if the crystal structure between materials is broken, it will cause a gap in the superconducting energy gap, and a gap in the superconducting energy gap will lead to a sharp reduction in all aspects of superconducting performance.
But the core of whisker (fiber) toughening technology actually comes down to the chemical bonds of the material.
As we all know, most metal materials are prone to plastic deformation because metal bonds have no directionality.
In materials such as ceramics, the bonds between atoms are covalent bonds and ionic bonds, and covalent bonds have obvious directionality and saturation.
In this case, the repulsive force is very strong when ions of the same sign of the ionic bond approach, so ceramics mainly composed of ionic crystals and covalent crystals have very few slip systems and generally break before slip occurs. (High School Knowledge
, stop saying you don’t understand!)
This is the fundamental reason for 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, whisker (fiber) toughening technology can make up for this very well. When the whiskers or fibers are pulled out and broken, a certain amount of energy is consumed, which is helpful 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. This film can absorb the force from your arm and maintain the shape of the chopstick inside.
Of course, the specific situation of using graphene for whisker (fiber) toughening will be more complicated.
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, organically combined through an extremely thin interface.
In this case, it is possible that the chemical bonds in graphene will replace the doped carbon atom bonds in the copper-carbon-silver composite.
Xu Chuan chose to use graphene as the toughening material because he took this into consideration.
This chapter is not over, please click on the next page to continue reading! Graphene is a pure single-layer, 'two-dimensional honeycomb lattice structure' carbon material. Its organic combination with the copper-carbon-silver material interface will not change the high-temperature copper
Composition of carbon-silver composite superconducting materials.
So in theory, it is still possible to achieve the goal by toughening 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 that 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 had left to prepare parameter information for the domestic controllable nuclear fusion experimental reactor, returned.
It not only brings detailed parameters of experimental reactors in major domestic controllable nuclear fusion research institutes, but also brings a list of domestic manufacturers that are qualified and capable of producing high-temperature copper-carbon-silver composite superconducting materials.
The first thing Xu Chuan looked at were the detailed parameters of experimental reactors in 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 information brought by Gao Hongming.
To put it loosely, there are currently more than a dozen controllable nuclear fusion research institutes in China, but only eleven fusion reactors.
This number is indeed quite large, but in fact most of these eleven fusion reactors are only experimental reactors or even device reactors.
The so-called experimental reactor refers to an experimental device that can meet the most basic experimental needs of plasma experiments.
As for the device pile, not to mention, it cannot even conduct an ignition experiment.
According to the information Gao Hongming brought, there are currently only two fusion reactors in China capable of conducting ignition operation experiments.
They are the magnetic confinement fusion tokamak device 'eat' of the Institute of Plasma Physics of the Academy of Sciences and the inertial confinement fusion device 'Shenguang' of the Ninth Institute of Technology.
The method of inertial constraint is completely different from magnetic constraint.
Magnetic confinement can be understood as allowing high-temperature plasma to flow and fuse in the device to form high temperatures.
Inertial confinement uses the inertia of matter to put a few milligrams of a mixed gas or solid of deuterium and tritium into a small ball with a diameter of about a few millimeters.
Then a laser beam or particle beam is uniformly injected from the outside, and the spherical surface evaporates outward due to the absorption of energy. Due to its reaction, the inner layer of the spherical surface is squeezed inward to form a high-temperature environment, allowing these few milligrams of deuterium and tritium mixed gas to explode.
, generating a large amount of heat energy.
If three or four such explosions occur every second and continue continuously, the energy released is equivalent to a million-kilowatt power station.
Simply put, inertial confinement is similar to a hydrogen bomb explosion, and then absorbs thermal energy from the explosion energy to generate electricity.
It's just smaller in scale and more controllable.
This method has little meaning for the plasma turbulence control model studied by Xu Chuan, because the fusion methods are completely different.
Therefore, after excluding the inertial confinement fusion device "Shenguang" of the Gongjiu Institute of Technology, the only experimental reactor he could choose was the "eat" magnetic confinement fusion tokamak device.
The ‘eat’ magnetic confinement fusion tokamak device, also known as the fully superconducting tokamak nuclear fusion experimental device, created plasma operating experiments of more than 50 million degrees and 100 million degrees in 2016 and 18 years respectively.
In 2017, it achieved a record of 101. seconds of steady-state long-pulse high-confinement plasma operation.
In China, it is the undisputed leader in the field of controllable nuclear fusion. Even if it is placed in the world, it is one of the top experimental reactors.
However, except for 'eat', other fusion devices are somewhat unsatisfactory.
Xu Chuan also did not expect that at the end of 2019, the domestic controllable nuclear fusion field would still be like this.
Indeed, technically speaking, China is already at the top of the list in terms of controllable nuclear fusion, and overall the technologies are quite good.
But in the experimental pile, it is indeed somewhat rare.
Except for the 'eat' magnetic confinement fusion tokamak device, there is currently no other experimental reactor that can perform ignition experiments.
Equipment such as the famous HKUST No. 1 kt fusion reactor, Circulator No. 2 hl-a and hl-m experimental reactors are basically still under construction and unfinished.
Even Circulator 2, which was recently completed, will have to wait until late 2000.
And even if it is completed, it does not have the ability to start ignition experiments immediately. It will take at least one to two years to complete various tests, and only after at least two and three rounds of ignition experiments can the plasma turbulence model be tested.
carry out testing.
This situation made Xu Chuan smile helplessly.
Now it seems that he has no choice at all.
The only good thing is that all parameters of the 'eat' magnetic confinement fusion tokamak device are quite excellent.
The main part of the eat device is 11 meters high, 8 meters in diameter, and weighs 400 tons. It consists of six major components, including an ultra-high vacuum chamber, a longitudinal field coil, a poloidal field coil, an internal and external cold screen, an external vacuum Dewar, and a support system.
It has 16 large "d" shaped superconducting longitudinal field magnets, which can generate a longitudinal field magnetic field intensity of 3.t; 1 large poloidal field superconducting magnet can provide a magnetic flux change ΔФ≥10 volts per second; through these poloidal field superconducting magnets
The magnetic conductor will be able to generate a plasma current of ≥1 million amperes; the duration can reach more than 1,000 seconds, and the temperature will exceed 100 million degrees under high-power heating.
This series of parameters is quite excellent even in the whole world.
With excellent equipment, coupled with the plasma turbulence mathematical model, even if it is only a phenomenological level model, Xu Chuan is confident of breaking the current record of the longest operating time of the tokamak device.
It is not impossible to even chase the stellarator's operating time record.
After reading the information in his hand, Xu Chuan gently shook his head and sighed: "I didn't expect that the development of controllable nuclear fusion in China would be like this."
On the sofa, Gao Hongming leaned forward and asked nervously: "Isn't there anyone who meets the requirements?"
This chapter is not finished yet, please click on the next page to continue reading the exciting content! Xu Chuan nodded, shook his head, and said: "There are some that meet the requirements, but only one. Judging from the data of the eat device in Luyang
It meets the requirements, but nothing else is acceptable.”
Hearing this, Gao Hongming breathed a sigh of relief and said with a smile: "As long as there is one that meets the requirements, the leader of the EAT device is Academician Chen Mingji. He is also the person in charge of our country's connection with the ITER international fusion project. I will follow up here.
I will go and communicate with Academician Chen."
Xu Chuan nodded, thought for a while and said: "I should have gone there in person, but recently I was studying how to optimize high-temperature copper-carbon-silver composite superconducting materials with Academician Zhang Pingxiang, and I really couldn't get away from it.
.”
"Well, I'll ask Academician Peng Hongxi to go with you. It seems to be more serious. After all, if you want to use other people's equipment, you also need to modify the control model. For controllable nuclear fusion, it is also a big deal.
.”
Gao Hongming smiled and nodded, saying: "It doesn't matter. You can do your research first. I believe Academician Chen will understand."
After a pause, he continued: "By the way, regarding the work you previously communicated with Mr. Qin about the production of high-temperature copper-carbon-silver composite superconducting materials, I will also provide information on the manufacturers that are qualified and capable of producing it.
I brought it here with me by the way, do you want to take a look first?"
Xu Chuan nodded and took the information from Gao Hongming. Just as he was about to look through it, he thought for a while and said, "By the way, I just looked at the information. The 'eat' magnetic confinement fusion tokamak device still uses niobium."
Titanium alloys as superconducting materials.”
"About this application for the 'eat' magnetic confinement fusion tokamak device, you can discuss it with Academician Chen. I will not get it for free, and will make some compensation."
"If he is willing, I can provide him with the first batch of high-temperature superconducting materials for free after the high-temperature copper-carbon-silver composite superconducting materials are produced. I believe that the performance of high-temperature copper-carbon-silver composite superconducting materials can make
The 'eat' magnetic confinement fusion tokamak device goes one step further."
p: I got my computer back this afternoon, but it’s too late. I’ll do a double update tomorrow, and I’d like to ask for a monthly ticket (it’ll cost me more than 500 yuan to fix it, woo woo ┗t﹏t┛,)