Chapter 1582: Tearing off the tape may not work

"I don't know much about space." Du Lin waved his hand. "I just want to ask, do you think... is it possible to use magnetohydrodynamic propulsion technology on submarines? To truly achieve 'no propellers and no sound'?"

The idea of ​​magnetohydrodynamic propulsion has existed for a long time, but the fact that it was brought up for discussion by the equipment department clearly shows that there is something more than just a "concept".

For example, the research on electromagnetic flow control technology and electromagnetic fluid mechanics promoted by Chang Haonan himself is equivalent to taking a big step forward on this road.

But even so, it is not enough.

He shook his head almost without thinking, and said affirmatively:

"At least at this stage, it's not very realistic."

He saw Du Lin's confusion and explained in detail: "The basic principles are indeed the same, but the medium characteristics and actual needs are very different."

He picked up the pen on the table and quickly drew a diagram on the note paper:

"To stimulate a strong electromagnetic field in seawater that can generate macroscopic thrust, the required current is much larger than that in air. On the one hand, the energy consumption is very high. Even nuclear reactors... at least fission reactors cannot meet the demand. On the other hand, strong current will also generate a lot of heat. Combined with the characteristics of the water environment, the problem of electrochemical corrosion must also be considered."

Chang Haonan's change of words in the middle was actually just for the sake of rigor, but it sounded like something else to the other party.

Du Lin pinched his chin and said, "You mean... we can consider fusion reactors?"

"No..." Chang Haonan held his forehead helplessly.

The other party obviously chose the wrong focus.

In many cases, great force can indeed work miracles.

But the force of nuclear fusion is a bit too great.

"What I mean is that unless we can find and apply on a large scale practical superconducting materials with a critical temperature near room temperature and a very high critical magnetic field," Chang Haonan drew two circles on the electrodes and magnetic field coils in the schematic diagram, "only superconductivity can solve the energy consumption and strong magnetic field problems."

Du Lin nodded and frowned, with a complicated expression: "It sounds... not much simpler than controlled nuclear fusion?"

After all, I come from a science and engineering background, so I have some basic understanding of this concept.

"Indeed." Chang Haonan put the note paper and pen on the table at the same time: "In fact, the biggest obstacle facing controlled nuclear fusion at present is also the problem of superconducting materials."

"Isn't it a plasma confinement control problem?" As long as they didn't discuss specific technical issues, Du Lin could really chat for a few words. "Aren't inertial confinement and magnetic confinement two technical routes for confining plasma?"

Chang Haonan: "Director Du also knows about this?"

Du Lin recalled with a smile: "I attended a few lectures a few years ago and have some impression of them."

"Well...it was true before." Chang Haonan replied, "but it's not true now."

After finishing speaking, he immediately added:

"For us, it's no longer the case."

"..."

Du Lin originally wanted to continue responding with a joke, but when the words came to his lips, he suddenly realized that the amount of information behind this sentence was simply explosive.

I opened my mouth several times, but no sound came out.

Chang Haonan quickly regained his composure and brought the topic back to the original track: "In fact, although there is overlap and even duplication between the research on magnetic fluid and plasma, if we really want to make an analogy, the propulsion method that matches the plasma effect in a water environment is not magnetic fluid propulsion."

"Oh?" Du Lin raised his eyebrows and temporarily put aside his previous shock.

"Use high-energy pulses to discharge instantly in the water to generate high-temperature plasma channels, causing violent vaporization and expansion of the water body, and use the recoil force to propel it forward." Chang Haonan picked up the wireless mouse on the table and gestured a few times behind it. "This is called underwater high-voltage discharge coupled with steam explosion propulsion, and the engineering difficulty is relatively small."

Before he finished speaking, Du Lin shook his head repeatedly: "What about the noise? With this kind of propulsion method, each pulse discharge is equivalent to a small underwater explosion, right?"

"That's right." Chang Haonan nodded, "That's why I just said that the actual needs of underwater propulsion are also very different from aerospace."

"This form of propulsion is almost equivalent to running a steam train underwater. There is absolutely no concealment and no tactical value."

Driving a train underwater was an exaggerated evaluation made by the US military in the early years on the noise of the early Type 09I submarines.

But when it comes to steam explosion propulsion, it's really a pretty standard description.

"It seems that we are still stuck on the materials."

After listening to this, Du Lin sighed deeply, leaned back on the sofa, and sounded a little helpless.

But soon, he sat up again: "Speaking of materials... I remember you guys recently formed something very powerful... some kind of alliance..."

"Micro-characterization Technology Alliance." Chang Haonan added considerately.

“Will there be a technological breakthrough soon?”

"Yes." Chang Haonan's answer made the other party's eyes light up, but then he changed the subject, "But even I can't be 100% sure where the breakthrough will appear."

After a brief silence, he continued:

"Physicists' pursuit of new materials is endless." His tone was full of a clear understanding of the boundaries of science. "We have just made a breakthrough in atomic array materials and opened a new door with the help of MTA-01, but we are still at the foot of the mountain."

“Every breakthrough does bring us a little closer to the mountain, and we can see more climbing paths, but the mountain is still there.”

"..."

……

Two days later, Li Yabo knocked on Chang Haonan's office door with his laptop.

He has dark circles under his eyes but looks in good spirits.

Obviously there was something to be gained.

"Teacher, I followed my previous ideas and conducted several rounds of attempts using the 'supersaturated deposition-controlled annealing repair' method." He handed the computer to Chang Haonan, and a report file appeared on the screen. "This is the test result of the best batch of samples."

Chang Haonan slid two fingers on the touchpad and quickly found the three-dimensional imaging results of MTA-01.

In the image, atoms are arranged neatly and orderly, just like a grid drawn with the most precise ruler, with only slight dislocations or vacancies in very few areas. The three-dimensional point cloud of APT also shows a very high degree of spatial order.

"A honeycomb lattice is formed on the surface of the substrate, and the regularity of the atomic array is very good." Chang Haonan commented, "The defect density..."

He scrolled down and saw the number 1.7%:

"It is also very low, and most areas are close to the theoretically perfect structure. It seems that the annealing process and substrate pretreatment have found the right direction."

After that, he reviewed the images and data in the report again, and then concluded: "From the perspective of structural integrity alone, this is better than any batch of samples we have observed before..."

The touchpad sliding motion stops.

Because the report has come to an end.

It was much shorter than he expected.

"What about the optical performance test?" Chang Haonan confirmed that he had not missed any part. "How is the negative refraction property? How about stability?"

“Uh…” Li Yabo’s smile froze instantly, replaced by an awkward expression: “After the sample was made into a film, it was almost pure black, and the absorption rate of visible light and near-infrared was ridiculously high… I couldn’t measure any effective transmitted light signal at all, let alone negative refraction…”

Chang Haonan was also stunned, and then burst into laughter.

This is a typical scientific research episode - pursuing a certain performance to the extreme, but forgetting the original goal.

Everyone has encountered similar situations to some extent, so there is no need to be overly harsh.

What's more, the progress in the synthetic route is real.

He picked up the report again and focused his eyes on the microscopic structure images.

In particular, the arrangement of the atomic array and the interface state of the substrate material.

The office fell into a brief silence, with only the faint sound of shuffling papers.

Li Yabo looked at his mentor who was deep in thought with some trepidation.

Time passed by minute by minute.

Suddenly, Chang Haonan's fingers stopped and his eyes were fixed on the interface area where the atomic array contacted the substrate.

A bold idea flashed through my mind like lightning.

And confirmed the feasibility of this idea in the next second——

Through the function of the free system.

"Yabo." Chang Haonan raised his head and pretended to say "I'm not sure either." "Since this tightly packed array structure leads to strong light absorption, can we try to make a single layer... or a two-dimensional array with atomic thickness, and then splice it on the Z axis?"

"In this way, we can achieve optical anisotropy, with the negative refraction and light transmittance we want only in the direction perpendicular to the layer. As for the direction parallel to the layer... we don't need that direction to have special optical properties anyway?"

Li Yabo immediately followed his thoughts: "You mean a single atomic layer like graphene..."

"Not exactly the same." Chang Haonan picked up a pen and quickly sketched on the paper. "If I have to say, it may be more similar to a single layer of germanene or stanene loaded on a specific metal substrate, such as cadmium. They are also two-dimensional...quasi-two-dimensional materials, but the atomic orbital hybridization and spin-orbit coupling are stronger, and it is easier to form a two-dimensional topological insulator state under certain conditions."

Germanene is actually a double-layer structure, not strictly two-dimensional.

But it also meets Chang Haonan's requirements.

He pointed at a few electron tracks:

"The key lies in the separation of the bulk state from the topologically protected quantum edge states... In the edge states, the transport of electrons can be dissipationless, similar to superfluidity. If we can precisely design the material so that the light field is strongly coupled mainly to these protected, low-dissipation edge states, it may be possible to achieve low-loss negative refraction effects."

This time, Li Yabo's eyes were a little straight, and it took him a long time to fully absorb what he had just said.

"So... do you want to try removing the tape?"

It is now the end of 2012, and graphene has even won the Nobel Prize, so the initial separation method has naturally become a legend.

"I'm afraid it won't work." Chang Haonan shook his head. "This type of material doesn't have van der Waals forces between layers like graphene, so it's impossible to obtain a single layer using relatively rough methods such as mechanical exfoliation or grinding exfoliation..."

"But this kind of material is even more impossible to separate by chemical means?"

"So we have to find a suitable substrate material and consider using epitaxial growth to directly obtain the finished product."