Siheyuan (traditional courtyard house): Starting with the Korean War, returning home to take charge

When He Yuzhu got out of the jeep, it was still dark. The gate of the Shanghai Radio Factory was wide open, and the old gatekeeper was dozing in his booth. Hearing footsteps, he opened his eyes, hurriedly stood up, and saluted. He Yuzhu waved his hand and walked inside.

The factory area was quiet, the streetlights were still on, their dim yellow light illuminating the dusty factory buildings. In the distance, the muffled hum of machinery could be heard, like someone speaking with their mouth covered. He walked for more than ten minutes, rounding a small hill piled high with scrap metal, and saw the windowless, grayish-white building. The building was low, nestled in the open space, like a turtle with its neck tucked in. Two people stood at the door: Lin Jianguo and Factory Director Zhou. Lin Jianguo saw him, took two steps forward, then stopped.

He Yuzhu walked over. "How is it?"

Lin Jianguo threw his cigarette butt on the ground and stomped it out. "We've been working on this for seven days and seven nights, and there were three failures. Once the coolant pump leaked, once the memory modules burned out, and once a power grid fluctuation caused the storage array to crash. They're all fixed now, and it's stable." He paused, his voice lowering. "But... there's a problem."

He Yuzhu looked at him.

Lin Jianguo didn't continue. He turned around, walked to the iron gate, took out his key, inserted it into the lock, and turned it twice. When the iron gate opened, a rush of cold air rushed out, carrying the smell of heated electronic components. He Yuzhu followed him inside.

Galaxy VI was twice the size of Galaxy 5. The server racks were arranged in eight rows, each with a dozen or so units; the light gray metal casings gleamed coldly in the dim light. Indicator lights flashed densely, red and green, like navigational beacons on a dark sea. The fans hummed, not loud, but the vibrations made my feet numb. Several young technicians sat at their workstations; some stared at the screens, some flipped through notebooks, and some were asleep, their heads resting on their arms, their faces contorted in pain.

Lin Jianguo walked to the control panel, his fingers hovering over the keyboard, but he didn't type. The screen was lit, and data scrolled up line by line, too fast to see clearly. He turned to the side, showing He Yuzhu one of the windows.

"Dean, this is a simulation of the magnetohydrodynamic stability of a tokamak plasma. We've been running it for two days and we've found a problem."

He Yuzhu leaned closer to the screen. The window displayed concentric rings of colored stripes, like tree rings, the color deepening towards the outer edges. Lin Jianguo pointed to those stripes.

"This is a magnetic disturbance. Under normal circumstances, the disturbance would be suppressed by the magnetic field and would not be amplified. But our design will resonate in a certain mode, the disturbance will become stronger and stronger, and eventually the plasma will go out of control and crash into the first wall."

He Yuzhu pressed his hand on the table. "What would happen if we crashed into the first wall?"

Lin Jianguo didn't answer directly. He flipped through the notebook on the table, found a page, and handed it over. "These are the simulation results. After the plasma goes out of control, the local temperature of the first wall will instantly rise to over 3,000 degrees Celsius, the material will melt, and the reactor will shut down. In severe cases, even the vacuum chamber may be damaged."

He Yuzhu took the sheet of paper. It contained a temperature distribution chart; the red area resembled a ball of fire, spreading outwards from the center. He put the paper down and looked at Lin Jianguo. "Can it be changed?"

Lin Jianguo was silent for a moment. "Yes. We can change the magnetic field configuration, the coil layout, and the material of the first wall. But we have to calculate, many times. It takes two weeks to calculate once for Galaxy 6, and a year to calculate dozens of times."

He Yuzhu said, "Calculate. Calculate until you find the optimal solution."

Lin Jianguo nodded, turned around, and typed a few lines of commands on the keyboard. The data on the screen jumped even faster. After he finished typing, he stared at the screen without saying a word.

A technician next to him woke up, rubbed his eyes, looked at Lin Jianguo, then at He Yuzhu, and quickly stood up. "Dean..." He Yuzhu waved his hand, sat down, and lowered his head to continue flipping through his notebook.

Director Zhou stood in front of the server rack, holding a report in his hand. He flipped through it, then put it down and walked over. "Director He, Galaxy-6 is operating at full capacity, consuming 10,000 kilowatt-hours per hour. The Shanghai power grid can't handle it, so we've specially pulled a high-voltage line from the East China power grid."

He Yuzhu asked, "What about the electricity bill?"

Factory Director Zhou gave a wry smile. "Several hundred thousand a month. The finance department is already complaining."

He Yuzhu didn't reply. He walked to the front of the server rack and reached out to touch the casing. It was cool and vibrated slightly. He squatted down to look at the fans underneath, then stood up to look at the indicator lights on top. The lights blinked slowly and steadily, like a patient breath.

"High energy consumption is not a problem. Once the fusion power plant is built, electricity will no longer be an issue."

Factory Director Zhou nodded and said nothing more.

The iron gate was pushed open. Qian Zhiyuan walked in, carrying a silver-white tin box. A label, handwritten and illegible, was affixed to the lid. He wore a faded blue cotton jacket, the cuffs rolled up, and his hands still bore traces of grease. He walked to He Yuzhu, placed the box on the table, and opened it. Inside, a black velvet cloth lined the surface, upon which lay a thin, dark gray board, barely thicker than paper. He picked up the board and handed it to He Yuzhu.

"It's newly developed. It's a ceramic matrix composite material."

He Yuzhu took it and weighed it in his hand. It was light, almost weightless. He flicked it with his finger; the sound was crisp, like tapping porcelain. He took out a key from his pocket and ran the tip across the surface, leaving not a single mark.

How much heat resistance?

Qian Zhiyuan looked at him. "The lab data is 3,000 degrees. I haven't actually tried it; I don't have the conditions. A vacuum furnace can only reach 2,500 degrees."

He Yuzhu handed the board back to him. "Three thousand degrees, is that enough?"

Qian Zhiyuan took the board and put it back in the box. He lowered his head, his finger pausing on the lid of the box. "Theoretically, it's enough. But when the plasma goes out of control, the temperature could exceed three thousand. There's also thermal shock; it's not steady-state heating, it's an instantaneous explosion." He looked up at He Yuzhu. "Director He, we've only tested this material in a vacuum furnace, not in a plasma environment. It's hard to say how much it can actually withstand."

He Yuzhu didn't speak. He turned around, walked to the wall, and looked at the cross-sectional diagram of the tokamak on the wall. A toroidal vacuum chamber, outer coils, the first wall at the very inside. He stood there for a long time.

"Make a small sample first, and test it in a tokamak. We'll see what happens after that."

Qian Zhiyuan nodded, picked up his suitcase, and left. The iron gate closed, but the lights in the server room were still on, and the fans were still running.

He Yuzhu stood at the control panel, watching the data fluctuate on the screen. Lin Jianguo sat in his chair, his eyes fixed on the screen, motionless. The technician next to him was asleep again, his head resting on his arm, his breathing very soft.

He Yuzhu walked behind him, picked up the notebook that had slipped to the floor, and put it back on the table. The open page of the notebook was filled with dense data, the handwriting messy, but each line was neat and tidy. He looked at it for a while, then closed the notebook.

Lin Jianguo turned around. "Dean, are Director Qian's materials... any good?"

He Yuzhu didn't answer. He patted Lin Jianguo on the shoulder. "Calculate it first. We'll talk about it after we figure it out."

Lin Jianguo nodded and turned back to continue staring at the screen.

He Yuzhu walked out of the machine room. As the iron door closed behind him, he heard a soft sigh come from inside. He didn't know who sighed.

The streetlights in the courtyard were still on, and the sky was already a hazy, grayish white. Birds chirped in the distance, their calls crisp and clear. He stood at the door, lit a cigarette, but didn't smoke it, watching it burn out on its own. Then he turned and walked towards the guesthouse. He didn't encounter a single person along the way.