Start as a top student and move towards the stars and the sea

It is these dislocations that cause the phase of the material to be destroyed, and the impact on the structure is even more serious than before the excess K element was added.

"In this way, adding excess K element to K-containing iron-based superconductors is a wrong route in itself."

Although Ning Chen found the root cause of the problem, Ning Chen still had no good solution at this time.

The whole problem seems to be stuck in an infinite loop, because even if excess K element is not added, the problem of uneven microstructure at high temperatures still cannot be solved.

This special property seems to indicate that this kind of iron-based superconductor containing K really cannot be processed into wire strips.

After experiencing constant failures, the project team decided to temporarily skip the research on this K-containing iron-based superconductor and then study wire strip processing solutions for other iron-based superconductors.

Ning Chen has not completely given up on this iron-based superconductor, and will still try to think of a solution to this problem in his spare time.

…

Unknowingly, the project research on iron-based superconductor wire strips has been in progress for a month.

As the school started approaching, Tao Wei knew that Ning Chen would still be attending classes at Yanda, so he approached Ning Chen so that Ning Chen could temporarily leave the project team.

"Ning Chen, you have made many important contributions to the project team in the past month. Of course, I also know that you are still a student and very busy with your studies. You should go back to school first and wait until you have time on the weekends. , just come back to the project team."

After all, Ning Chen was not a member of Tao Wei's experimental group, but was specially invited to the experimental group by Tao Wei. Tao Wei was embarrassed to keep Ning Chen in the experimental group.

After listening to Tao Wei's words, Ning Chen did not answer immediately, and was also struggling with something in his heart.

Doing experiments at the Chinese Academy of Sciences and studying at Yanda are very valuable and attractive things for Ning Chen.

But Ning Chen also knew that he could not stay at the Chinese Academy of Sciences forever. After all, this was a very long-term project that might last several months or even years.

Tao Wei's original intention was just to let Ning Chen take time to come to the project team to participate in some experiments while he was in Yanjing.

Thinking of this, Ning Chen said:

"Okay, Academician Tao, after I return to Yanda, I will try to come over every weekend to participate in the experiment."

"Well, that would be the best. Ning Chen, I really hope you can be my student, so that I can keep you in the laboratory, haha."

On a similar note, Professor Ren Mingshan of Yanda University also told Ning Chen that no teacher would want to have a student as outstanding as Ning Chen.

After thanking Tao Wei, Ning Chen also planned to go back to the dormitory, pack his things and prepare to leave.

On the way, Ning Chen recalled every detail of his previous experiments in Ren Mingshan's laboratory.

When Ning Chen recalled the device "three-dimensional Helmholtz coil", he suddenly remembered something.

"By the way...magnetic field!"

At this moment, a bright light seemed to flash in Ning Chen's brain, giving Ning Chen a new way of thinking.

Speaking of which, when studying K-containing iron-based superconductors before, the reason why the microstructure of the material appeared to be uneven was because the excessive addition of K element would cause uneven distribution of K element.

In this way, a region is created in the superconductor that exerts force on the magnetic flux vortex, which is the magnetic flux pinning center.

And if a new magnetic field is applied to the outside during the material processing process, it is theoretically possible to solve this problem!

Thinking of this, Ning Chen suddenly became excited.

Although Ning Chen is not sure whether his idea is correct, at least this new plan provides new possibilities for research on the subject.

At this time, Ning Chen was a little lucky that he had been able to participate in Ren Mingshan's experiments before, which allowed him to gain a lot of subject experience and greatly enrich his knowledge and ideas.

Ning Chen immediately stopped returning to the dormitory, turned around and headed back to Tao Wei's office.

Seeing Ning Chen's sudden return, Tao Wei was also surprised and asked quickly:

"Ning Chen, what's wrong?"

"Academician Tao, does our Chinese Academy of Sciences have the equipment of 'three-dimensional Helmholtz coil'?"

"'Three-dimensional Helmholtz Coil'...there is this device, but what are you going to do?"

"That's it, Academician Tao, I just suddenly thought of a new idea. I think the core reason why K-containing iron-based superconductors cannot be processed into wire strips is because of the magnetic flux generated in the superconductors. The area where the vortex exerts force..."

Ning Chen told Tao Wei exactly what he had just thought.

At first, Tao Wei did not expect that even though the experiment had entered an infinite loop, Ning Chen was still thinking about how to solve the problem of processing K-containing iron-based superconductor wire strips.

But after Tao Wei listened to Ning Chen's idea, he realized that Ning Chen's idea could really be tried.

"In the process of material processing, three-dimensional Helmholtz coils are used to artificially create a magnetic field in the processing environment to offset the area where the magnetic flux vortex exerts force... Ning Chen, your idea is really ingenious !”

Although Tao Wei didn't know whether Ning Chen's method would actually work in the end, it was incredible to think of such an unconstrained idea.

"When I was doing experiments at Yanda, I accidentally came into contact with this equipment, so I suddenly thought of this idea."

Due to scientific research confidentiality, Ning Chen cannot yet mention to Tao Wei what topics he has used this equipment to study before.

Tao Wei did not ask about these things, but said:

"Ning Chen, if you are not in a hurry to return to Yanda, let's try your method first to see if it really works."

Naturally, Ning Chen would not miss these few days. The new idea he had finally come up with would definitely have to be personally participated in the experiment to verify whether this idea was really feasible.

Even if the final result is failure, Ning Chen will accept the result calmly, but if he does not participate in the experiment, it will be a permanent regret.

"Don't worry, Academician Tao. I'll go back to Yanda after we verify this idea."

After determining the new experimental arrangement, Tao Wei and Ning Chen came to the laboratory together and told everyone about Ning Chen's experimental idea.

After listening to Ning Chen's novel idea, everyone was amazed by Ning Chen's idea. At the same time, they also regained hope for the research on K-containing iron-based superconductor wire strips.

Tao Wei contacted other professors at the Chinese Academy of Sciences and borrowed a three-dimensional Helmholtz coil equipment.

After a while, several students sent the equipment to Tao Wei's laboratory.

Ning Chenxin said that this scene seemed familiar.

It seems that for academic leaders like Tao Wei and Ren Mingshan, borrowing experimental equipment is really just a phone call away.

This three-dimensional Helmholtz coil is very similar to the one at Yanda. Ning Chen thinks that this may be the same model of equipment.

When he was in Ren Mingshan's laboratory before, Ning Chen saw how Ren Mingshan used this equipment, and he basically learned the main operation methods.

Therefore, Ning Chen decided to take the lead in testing and simulating magnetic fields by himself.

After preparing for the experiment, everyone started a new round of experiments.

Following the previous experimental ideas, everyone added excess K element to the K-containing iron-based superconductor powder again.

Different from previous experiments, this time Ning Chen used a three-dimensional Helmholtz coil to test the magnetic field in the line.

Due to the complete diamagnetism of superconductors, there is no magnetic field in normal superconducting circuits.

Because the surface of a superconductor can generate a lossless diamagnetic superconducting current, the magnetic field generated by this current happens to offset the magnetic field inside the superconductor, thus causing a scene where the magnetic induction intensity within the superconductor is zero.

However, after adding excess K element, the internal structure of K-containing iron-based superconductors is destroyed, and the completely diamagnetic properties disappear.

After some testing, Ning Chen obtained the magnetic field data in the pinning center.

When this magnetic field data was opened in a three-dimensional modeling manner, Ning Chen's expression was not so optimistic.

Because the entire magnetic field is dynamic, it is not easy to simulate it accurately.

Although Ren Mingshan previously used three-dimensional Helmholtz coils to shield the geomagnetic field, he also created a dynamic magnetic field.

But for the same dynamic magnetic field, the difficulty of simulation is also very different.