I started with a ship full of max-level veterans, and I'm just a complete noob.

On the evening of the third day, the No. 3 furnace completed its sixth propulsion.

The furnace position was occupied for six consecutive tests, and all other items on the furnace duty roster were postponed. The staff of the Institute of Physics took turns recording the protective gas flow, pipe pressure and furnace temperature changes, while the 502 technical team guarded both sides of the transmission mechanism and control console.

There were two disturbances in the six passes.

The first incident occurred in the middle of the second push. The pressure of the protective gas cylinder gradually decreased, and the flow meter float slid down one notch. Jiang Ming first saw the furnace temperature curve shift upward on the paper tape. He then asked Da Liu to open the spare gas cylinder, and the pressure regulator replenished the airflow. The control loop pulled the temperature back to the set line.

Fang Xudong cut out this curve separately and labeled it as atmospheric flow disturbance.

The second occurrence occurred near the end of the fourth pass. Irregular bright spots appeared on the crystalline surface at the end of the germanium rod. After the quartz boat passed the coil, a rough grayish-white layer formed at the edge of the tail.

Old Sun stopped the handwheel in front of the graduation line and reached out to check the record.

"If the crystallization at the tail end can't keep up, continuing to push it will bring this part into the material later on."

Jiang Ming checked the pyrometer reading and then verified the temperature change of the trailing edge sensor.

"Cut five millimeters off the tail end, then reset to zero again for the next pass."

Old Sun took out a small cutting frame, put the germanium rod into the positioning groove, cut off the tail end along the marked line, and then used fine sandpaper to treat the broken edge.

Lin Lanying sealed the cut-off portion separately and wrote on the seal that the fourth crystallization at the tail end was abnormal.

When the furnace started again for the fifth time, the furnace's advance speed remained at 0.8 millimeters per minute. Jiang Ming added the length change caused by the shortening of the tail end to the process card, and Fang Xudong transferred the new end mark to the paper tape.

After the sixth pass, the germanium rod was removed from the quartz boat. The front part of the rod was smooth, while the tail part retained a clear enrichment zone. The removal location was further back than the abnormal area in the fourth pass.

Lin Lanying pushed the four-probe measuring station to the side of the long table, wiped the tips of the probes clean, first calibrated the germanium rod at the head, and then measured every centimeter along the length.

The germanium rod is fixed on the cork clamp, and the four contacts of the probe are pressed down in sequence. The current source sends a low-voltage test signal, and the voltmeter reading is converted and written into a table.

One centimeter, two centimeters, three centimeters.

Fang Xudong was in charge of reporting the numbers, Lin Lanying was in charge of measuring, Da Liu wrote the data on the blackboard, and Jiang Ming checked the spacing between each measuring point.

When the resistivity curve reaches the front section of the rod, the fluctuations gradually narrow. After entering the middle section, the reading falls into a flat range. Near the tail, the curve bends downward, and the enrichment trend of impurities in the last ten centimeters is very clear.

Lin Lanying entered all the data into the coordinate paper, connected the measuring points with a ruler, and formed an approximately horizontal line in the first two-thirds.

She pasted the graph paper onto the blackboard, her pencil hovering beside the flat curve.

"This uniformity has exceeded the threshold of three nines."

Old Sun was disassembling the transmission box when he heard this and looked up.

"Can it be used?"

"The front part can be selected for subsequent experiments, but the tail part still needs to be cut off, and the part near the transition zone also needs to be marked separately."

Jiang Ming circled the length of the enriched area at the tail and then wrote the cut-off line next to the curve.

Huang Kun took the germanium purification record from the Institute of Physics the previous year into the furnace room. The curve on the old record was manually cut into many undulating segments by adjusting the voltage. After three rounds of adjustment, the readings at the beginning and end were still in a state of continuous change.

He placed two graph sheets side by side on the table.

"You did it six times this time."

"Six times, with one gas cylinder changed in between, and the tail end cut by 5 millimeters. Other parameters are maintained according to the process card."

"After three times last year, the curve is still rising."

"At that time, the furnace temperature fluctuated by more than one degree, which would change the width of the molten zone and disrupt the distribution of impurities."

Huang Kun looked along the new curve once, then turned his gaze to the furnace temperature paper strip.

"Accurate temperature control is a prerequisite."

He wrote this sentence in the notebook, the pen tip pressing against the paper, leaving a clear ink mark.

Lin Lanying organized the resistivity data of the head, middle section and tail into three columns, and then pushed Huang Kun's record book in front of Jiang Ming.

"Based on these results, the closed-loop control of 502 is far superior to manual pressure regulation. Once the temperature stabilizes, the effect of regional purification will become apparent."

Jiang Ming nodded and reached out to fold the six strips of paper in order.

Lin Lanying's judgment is grounded in engineering facts: the controller's response, the decomposition of heat capacity, and the fixation of boundary conditions are what make that curve repeatable.

All she saw was that the furnace was finally working as planned. Jiang Ming knew that every parameter of the No. 3 furnace had been broken down into measurable, correctable, and verifiable steps.

"After the tail section is removed, the remaining polycrystalline germanium will be stored," Jiang Ming said. "The next step is to grow single crystals."

Fang Xudong approached with the coordinate paper in his hand.

"After the purified polycrystalline germanium is remelted, the seed crystal contacts the surface of the melt. The pulling speed and rotation speed must be controlled together, and the temperature field must also be kept stable."

"The seed crystal rotation speed is currently only within an empirical range; the data must be obtained from the first growth."

Lin Lanying looked at him.

"The Institute of Physics currently does not have a single crystal furnace."

"502 is being modified."

Jiang Ming put the last temperature curve into a folder and returned to the Third Electronics Factory with Fang Xudong and Lao Sun.

In Lab 502, Wu Hanzhang had already dismantled the old vacuum evaporation equipment. The original evaporation hood had been moved to the wall, and the furnace frame was now fitted with a newly processed heating seat. The top lifting mechanism was not yet encapsulated, and several copper coils were resting against the worktable.

Old Sun first inspected the graphite crucible. The crucible had been machined into shape, with a smooth inner wall, but there was a difference in thickness at the bottom.

"It's off by 0.3 millimeters."

He handed the micrometer to Jiang Ming, then picked up the scraper and began to work on the bottom of the crucible again.

"After heating, the bottom is heated unevenly, and the melt will move first on this side, and the contact position of the seed crystal will also be off."

Jiang Ming placed the crucible on the flat plate and rotated it once. There was a spot on the bottom edge that did not make proper contact with the flat plate.

"Continue the repairs, and make sure the thickness at the bottom is consistent first."

Fang Xudong sat at another table, organizing the data from the six rounds of regional purification. The table listed the progress speed, furnace temperature fluctuations, protective gas flow rate, and resistivity changes for each round.

Wu Hanzhang took out two documents from behind his desk and placed them in front of Jiang Ming.

One document was a preliminary draft of the 24 gigahertz pre-research plan, and the other was a notification from the Institute of Physics.

"Wang Shouwu from the semiconductor research group will visit the Institute of Physics next week to inspect the purification results of Furnace No. 3."

He tucked the cigarette behind his ear and tapped the notice with his fingers.

"People from the semiconductor industry are coming; be prepared to get questioned."

Jiang Ming opened the notice and saw Wang Shouwu's name in the "Visitors" column, while the only listed person accompanying him was the "Research Group Technician".

Fang Xudong looked up from in front of the data table.

"Will he look at the temperature control first, or the germanium material first?"

"See what he wants to ask."

Wu Hanzhang took the 24 gigahertz scheme and turned to the device section.

"We also need to prepare here. The K-band receiver preamp and single-crystal germanium are both waiting to be moved forward. The time taken by the two furnaces will overlap."

Jiang Ming looked at the single crystal furnace under modification. On the table were crucibles, wire pullers, and seed crystal chucks. All the components had taken shape, but there was still a verification process before they could operate stably.

He picked up a pencil and added three test items to the process sheet.

Pulling speed, seed crystal rotation speed, melt temperature field.

"First, we'll build the single crystal furnace, then we'll use the first sample to answer the questions."

Wu Hanzhang glanced at him, the cigarette still tucked behind his ear.

"Wang Shouwu won't just look at the samples."

"Then let's display the curves and samples together."

Old Sun was grinding the bottom of the crucible behind the workbench, and the graphite powder fell into the iron pan. Fang Xudong put the six curves into a file bag according to their numbers.

At night, the lifting mechanism of the single crystal furnace was equipped with a worm gear, and the top chuck could move up and down along the guide rail, but the rotary motor was still missing a suitable speed regulating resistor.

Wu Hanzhang took out an old motor speed controller from the spare cabinet and handed it to Da Liu, asking him to remove the resistance wire and rewind it.

Standing beside the furnace frame, Jiang Ming transferred his experience in closed-loop control of Furnace No. 3 to the new equipment. He first listed the thermal inertia of the crucible, the response of the induction coil, and the heat dissipation of the furnace body, and temporarily filled in the initial range of the parameters.

Old Sun put down the scraper.

"Jiang, the bottom of the crucible has been leveled."

Jiang Ming took the micrometer and measured again; the thickness difference was now within the scale's resolution range.

"We'll load the furnace and test it under no-load conditions tomorrow."

"Should we heat the crucible first?"

"First, look at the temperature field."

Wu Hanzhang put the notice into a folder, and the sound of footsteps of the duty officer changing shifts could be heard outside the office door.

Wang Shouwu will arrive at the Institute of Physics in two days. The six-cycle curves of Furnace No. 3 have been sealed, but the single crystal furnace has not yet grown its first crystal.

Fang Xudong put the last page of data into the file folder, then suddenly asked, "What if we can't pull out a single crystal on the first try?"

Jiang Ming looked at the empty seed crystal clip at the top.

"Then leave the failed segment and see where it starts to go wrong."