Chapter 452 High Temperature Superconducting Coils

Forty-seven days after the feasibility study was approved. Qian Zhiyuan stayed up for three nights in the lab, with three band-aids on his fingers, all from cuts made by the edge of the strip while winding the coil.

Ma Yuejin stood at the laboratory entrance, not going inside. He held an enamel mug in his hand; the tea was long cold, but he didn't drink it. He stared at the five-meter-diameter black coil for a while before speaking, his voice much lower than usual.

"Five meters, fifteen Teslas... Can you really do that?"

Qian Zhiyuan squatted beside the coil, not looking up. The calipers slid across the surface of the strip and stopped. Two seconds later, he spoke.

"The critical current density of the strip is sufficient." He paused, "Seventy-two hours of continuous testing showed no loss of overcurrent."

The last four words were emphasized, as if trying to convince himself.

Ma Yuejin walked in, squatted down, and tapped the copper sheath on the surface of the coil with his knuckles. It made a clanging sound. "You said the same thing last time. As a result, after three minutes of powering it on, smoke started coming from the connector, almost setting the lab on fire."

Qian Zhiyuan paused for a moment. He didn't argue, stood up, put the calipers in his pocket, and walked to the control panel. His fingers hovered over a few buttons, but he didn't press them.

He Yuzhu walked in from the doorway without saying a word and stood next to the lab bench.

"The liquid nitrogen tank is connected. Once the valve is opened, the temperature reaches 77 Kelvin," Qian Zhiyuan's voice returned to its steady tone. "After power is applied, the magnetic field can reach 15 Tesla."

"Let's begin," He Yuzhu said.

Qian Zhiyuan pressed the liquid nitrogen injection button.

The sound of liquid flowing came from the pipes, like water being flushed through a pipe. White mist billowed from the vents on the surface of the coil, slowly spreading along the toroidal coil. The temperature in the laboratory dropped several degrees. Ma Yuejin shivered, placed the enamel mug on the table, and rubbed his hands together.

"The temperature has stabilized at seventy-seven Kelvin," the technician reported, staring at the screen.

Qian Zhiyuan glanced at He Yuzhu. He Yuzhu nodded.

He turned off the power switch.

The current began to climb from zero. The gauges on the control panel slowly deflected. The coil emitted a deep hum, like the lowest string of a cello being plucked. Ma Yuejin took a step back, his hand gripping the edge of the table, his knuckles turning white.

"Five amperes," the technician's voice remained steady.

"Ten amperes. Magnetic field value: 0.5 Tesla."

The buzzing grew louder and the frequency increased. The metal platform of the lab bench began to shake. Several screws rattled and clanged on the surface.

Qian Zhiyuan turned to look at He Yuzhu. "Dean He, the tremor was quite strong."

"Keep rising."

Qian Zhiyuan's hand paused on the knob for half a second. He gritted his teeth and continued turning.

Twenty amperes. Thirty amperes.

The trembling turned into violent shaking. The steel legs of the lab bench slid across the floor, making a screeching, screeching sound—as if it were about to fall apart. A wrench rolled off the metal platform, slammed onto the floor, and bounced twice.

Ma Yuejin bent down to pick it up, but stumbled and almost fell. He grabbed the edge of the table, his face pale. "Dean He, we can't raise it any higher! The lab bench is going to fall apart!"

The technician stood up from his chair and took two steps back. He didn't speak, but his lips were trembling.

Qian Zhiyuan's hand hovered above the emergency stop switch, but he didn't press it. He turned to look at He Yuzhu.

He Yuzhu didn't move. "Forty amperes."

Qian Zhiyuan took a deep breath and pushed the knob to forty.

The coil emitted a piercing scream—not a buzzing sound, but a sharp, tearing sound, like metal being ripped apart. One of the fixing bolts on the lab bench sprang off, hitting the wall and leaving a dent. Ma Yuejin instinctively crouched down, covering his head with his hands.

But the metal platform did not disintegrate.

The ten-kilogram iron plate above the platform began to rise slowly. One centimeter above the platform. Two centimeters. Five centimeters.

The iron plate hung in mid-air, completely still.

The laboratory fell silent.

The screams continued, but no one paid attention. All eyes were fixed on the metal plate.

Ma Yuejin squatted on the ground, his mouth open, forgetting to close it. The technician dropped his pen, bent down to pick it up, but failed twice—his hand was shaking.

Qian Zhiyuan withdrew his hand from the knob, clenched it into a fist, and dug his nails into his palm. He didn't speak, staring at the iron plate, his eyes reddening.

He Yuzhu walked to the metal plate and squatted down. He looked straight ahead at the gap between the plate and the tabletop. There was nothing in the gap, only air. He stretched out a finger and slipped it under the plate. His fingertip didn't touch anything.

"It's risky." He stood up, his voice calm. "Record the data. Take a measurement every thirty seconds for ten minutes."

The technician realized what was happening, bent down to pick up the pen, and wrote quickly in the notebook, the pen tip tearing the paper.

The humming continued, but the frequency stabilized. The iron plate hung five centimeters above the ground, completely still.

Ma Yuejin stood up, walked to the lab bench, and reached out to touch the iron plate. He pulled his hand back halfway, afraid of the electric shock.

"Dean He, this thing... it's really floating."

"Can't you see?"

"I saw it. I just can't believe it."

Ma Yuejin's voice was a little hoarse. He squatted down, tilted his head, and looked at the gap under the iron plate from the side. After looking for a while, he stood up, took out a cigarette to light it, glanced at the "No Smoking" sign on the liquid nitrogen tank, and put the cigarette back.

Qian Zhiyuan turned around from in front of the control panel. His eyes were still red, but the corners of his mouth were tugged upwards, not quite a smile.

"Dean He, the lift generated by 15 Tesla should, according to calculations, be able to lift 15 kilograms. We only put 10 kilograms."

"What's causing the vibration?"

Qian Zhiyuan walked to the bottom of the lab bench, squatted down to examine the fixing bolts. Smoke was rising from the splintered bolt holes, and the threads were worn smooth. He touched them, and they burned his hand, causing him to recoil.

"The electromagnetic force is too strong. The steel legs of the experimental platform are not strong enough. When the coil is energized, the attraction of the magnetic field to the ferromagnetic material pulls the experimental platform towards the coil. This platform is made of cast iron with a high iron content, so it is attracted."

Ma Yuejin leaned closer to look. "Change to a stainless steel countertop?"

"We'll change it tomorrow," He Yuzhu said.

He glanced at the suspended metal plate. It was still in mid-air, motionless.

"If the current is increased further, how high can it go?"

Qian Zhiyuan shook his head, stood up, and rubbed his knees, which were numb from squatting. "We can't add any more. The temperature at the strip joint is rising, and increasing the current further might cause it to exceed the limit. Fifteen Tesla is already the design limit for this coil. To increase the magnetic field, we need to wind a larger coil or use a wider strip."

How wide?

"It's currently ten millimeters wide. If it were twenty millimeters wide, the current would double, and the magnetic field would reach over twenty Tesla." He paused, "but the manufacturing process for wide wires hasn't been perfected yet. The wire drawing machines at the Beijing Wire Factory can only produce ten millimeters."

He Yuzhu was silent for a few seconds. "Go to the Beijing Wire Factory and work with them to tackle this problem. Produce 20mm strip within three months."

Qian Zhiyuan was taken aback. "Three months?"

"Three months."

Qian Zhiyuan bit his lip and said nothing more.

Ma Yuejin walked over from the lab bench, glanced at the data screen, and then at the iron plate. The iron plate was still hanging there.

"Dean He, if the vibration problem isn't solved, replacing the worktable with a stainless steel one won't help. The lab bench almost broke today. If we replaced it with the Kunlun, the ship's vibrations would cause structural fatigue."

Qian Zhiyuan took a tissue from his pocket and wiped the sweat from his hands. "Vibration indicates high energy conversion efficiency. The stronger the magnetic field, the greater the force, and the more intense the vibration. It's not a bad thing."

Ma Yuejin glared at him. "You almost blew up the lab just now, and you're saying it didn't cause any trouble?"

I'm talking about the principle.

"Can principles be eaten as food?"

He Yuzhu ignored their argument, walked to the control panel, and glanced at the data. "Shut down. Demagnetize."

Qian Zhiyuan walked back to the control panel and turned the knob. The current slowly decreased. The humming of the coil went from high to low, like the mournful cry of some animal.

The iron plate slowly descended. It landed on the table with a dull metallic clang.

The levitation disappeared. The iron plate lay back on the table, just like an ordinary piece of iron.

Ma Yuejin walked over and tapped the metal plate with his finger. It made a clanging sound. "It was floating just now."

He Yuzhu picked up the data record, glanced at it, and placed it on the table. "Director Qian, add an elastic buffer layer between the coil and the hull. It's a carbon nanotube rubber composite material that can both dampen shocks and provide insulation."

Qian Zhiyuan wrote it down in his notebook: "Propose a plan within a month."

He Yuzhu walked towards the door. Behind him, Ma Yuejin was still asking Qian Zhiyuan, "Twenty millimeters of strip, can you really do that?"

Qian Zhiyuan did not answer.

He Yuzhu walked to the door, paused for a moment, and did not turn around.

"Director Qian, you only have two months for the process of making 20mm wide strip. Not three months."