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

The next morning, when Jiang Ming arrived at the Institute of Physics with Fang Xudong and Lao Sun, Furnace No. 3 had already entered the protective atmosphere operation state. The flowmeter float was stopped at the specified mark on the process card, and the gas flow from the outlet pipe maintained a regular undulation on the glass soap film.

Lin Lanying stood beside the furnace frame, holding a newly copied sheet of material loading procedures in her hand.

"The germanium material was waste material sealed up last year. First, we weighed it, then measured its length, and took photos of both ends to record the process. After loading the material, we signed off on each step in sequence."

Old Sun placed his toolbox under the long table and took out a micrometer, a vernier caliper, and an iron plate covered with a soft cloth.

The duty officer took out a sealed box from the cabinet. After opening the lid, a gray-black germanium rod was found inside. The surface had fine lines left from the old cutting process. It was less than ten centimeters long and weighed less than the material used in the formal test.

Old Sun didn't rush to take it. He first put on his gloves and then wiped the tweezers and the iron plate with an alcohol swab.

"First weigh the pan, then weigh the material. Do this once for each step, and only when the values ​​match can this step be considered complete."

The duty officer moved the weights according to his instructions. Fang Xudong leaned over and looked at the balance pointer. After the swing narrowed, he reported the reading. Lin Lanying wrote the weight and number on the process card.

Jiang Ming stood next to the quartz tube, inspecting the sealing rings of the front and rear end caps. He ran his fingers along the edge of the cap to confirm that the old sealing material had been replaced with a new heat-resistant gasket. Then he re-matched the sensor position to the hot zone distribution map of Furnace No. 3.

"When the leading edge of the temperature measuring point is moved outward by two millimeters and pushed to the center of the coil, the leading edge of the melting zone can fall into the recording range."

Lin Lanying checked the drawings with a pencil, and then added a positioning line to the old drawings.

"Did you place it like this when you tested it under no-load conditions yesterday?"

"Yesterday it was based on the unloaded hot zone, today it's based on the length of the melting zone after loading. The two positions cannot be used interchangeably."

After measuring the length of the germanium rod, Lao Sun wrote the value on the edge of the process card. Then he used a thin copper sheet to measure the width of the inner groove of the quartz boat to confirm that there was still room for venting on both sides after the germanium rod was placed in.

Jiang Ming instructed him to place the germanium rod into the quartz boat, aligning the front end with the positioning hole of the push rod, and maintaining the specified distance at the tail end. Then, he sent the quartz boat into the quartz tube.

The push rod slowly extends from the rear end. Lao Sun uses the handwheel to move the end of the rod to the graduation mark position. Fang Xudong squats next to the transmission box and observes whether the zero position on the reading dial follows the rotation of the handwheel.

Old Sun turned the handwheel twice, stopped, and remeasured the distance between the end of the pole and the front edge of the quartz boat with a micrometer.

"About 0.1 millimeters off."

He took out a thin copper washer from the toolbox, disassembled the positioning base, inserted the washer into the contact surface, and then tightened the screws one by one.

The second measurement reduced the error to within the scale resolution range.

Lin Lanying stood on the other side of the stove rack, her previously tense brows gradually relaxing, and she placed the flowchart in her hand on the table.

"In the past, when we loaded the materials, we would first push the boat into the coil, and then estimate the position based on the markings on the outside of the furnace. It was always a bit off from the front or back."

"If the charging position is off, the width of the melting zone and the advancing length will change, making it difficult to explain with resistivity curves later."

Old Sun installed the front cover, Fang Xudong connected the air inlet pipe and pressure gauge, Jiang Ming checked each joint one by one, and then asked the duty officer to open the purified gas valve.

After the gas enters the quartz tube, the pressure inside the tube rises slowly. The change in flow rate at the outlet is transmitted to the paper tape by the recorder, and the temperature, pressure and flow rate curves are recorded simultaneously by the three pen tips.

Only after Jiang Ming and others stabilized their pressure did Da Liu connect the heating circuit next to the recording table.

The coil first emits a low hum, the ammeter pointer rises step by step along the scale, the inner wall of the quartz tube gradually lights up, the leading edge reading of the double platinum resistance rises before the trailing edge, and the differential controller then withdraws a portion of the heating power.

Fang Xudong stared at the paper tape.

"700 degrees, front edge 802, back edge 799, temperature difference 3 degrees."

"Keep warming up, don't rush to adjust."

Jiang Ming stood in front of the control panel, his finger hovering over the parameter seal, his gaze following the two curves toward 900 degrees.

After exceeding 930 degrees, the germanium rod in the quartz boat began to soften, and the originally gray-black surface became moist and shiny. The melting area spread along the center of the coil, and the liquid germanium appeared bright silver-gray in the protective atmosphere.

With the pyrometer aligned with the side of the quartz tube, Jiang Ming confirmed the front and rear boundaries of the melting zone through the observation hole, while Fang Xudong pressed the marking key to record the length of the melting zone on the paper tape.

"The front edge is 937.06, the rear edge is 937.01, and the width of the melting zone is 4.8 centimeters."

Lin Lanying checked the pyrometer reading and the double platinum resistance thermometer reading together, and then wrote down the first assembly data on the process card.

Before Huang Kun even arrived at the furnace room, the first crucial process of the furnace production had already begun.

Jiang Ming raised his hand to signal Lao Sun to start the advance.

Old Sun gripped the handwheel, first turning it forward a small increment to observe the engagement between the split nut and the push screw. Only after confirming that the quartz boat was moving smoothly did he turn it continuously at the speed specified in the process card.

The copper nut drives the screw, which in turn pushes the quartz boat. The front end of the germanium rod slowly enters the center of the coil, and the molten zone moves above the rod. A new crystallization zone gradually appears behind the liquid part.

Fang Xudong superimposed the propulsion speed curve and temperature curve onto the same paper tape, and reported the current position every time a marker was passed.

"The propulsion speed is 0.79 millimeters per minute, the temperature difference at the leading edge is 2.1 degrees Celsius, and the temperature difference at the trailing edge is 1.9 degrees Celsius."

Old Sun stared at the reading dial, keeping the handwheel turning at a consistent force. As the quartz boat moved inside the tube, the transmission frame emitted a continuous, light friction sound.

Jiang Ming moved the pyrometer from the front edge to the rear edge and then handed the two sets of readings to Fang Xudong.

"The trailing edge of the melting zone dropped slightly. Let's maintain the speed and wait for the next curve to appear before making a judgment."

Lin Lanying stood beside the recording table, watching the temperature line and the feed line gradually overlap on the paper tape.

She had initially anticipated that there would be many minor deviations during the first loading, as the sensor positions, propulsion mechanism, and protective atmosphere were interdependent, and any slightly faster movement in any part would cause the entire data to go astray.

Although the curve on the paper tape fluctuates at this moment, the fluctuations are still within an interpretable range.

After Lao Sun finished the last lap, Shi Yingzhou reached the finish line. Jiang Ming told him to stop pushing forward, continue to maintain the protective gas flow, and return to the starting position after the molten zone had completely solidified.

Fang Xudong cut the paper strip into three sections, labeling them as heating, propulsion, and cooling, respectively.

"First pass completed, maximum temperature fluctuation ±0.09 degrees."

After the temperature inside the quartz tube dropped to the specified range, Lao Sun returned the quartz boat to its original position. Jiang Ming opened the rear end cover and took out the germanium rod that still maintained its complete shape.

The germanium rod has a light gray sheen on its surface, and there are no polycrystalline fragments at the front and rear ends. There are also no large pieces of residue on the bottom of the quartz boat.

Lin Lanying took a handheld resistivity probe, first taking three points at the head, then moving along the rod to the tail to take three more points. Fang Xudong wrote each reading into a table.

"The average head is about 15 percentage points higher than the tail."

"Impurities are starting to concentrate towards the tail end; the direction is right."

Jiang Ming put the germanium rod back into the clean box and then asked Lao Sun to check whether the front-end positioning had changed due to thermal expansion.

Huang Kun then entered the furnace room, holding a notebook. He first looked at the paper tape, then at the resistivity data, and finally bent down to examine the surface of the germanium rod.

"It's alright, I'll walk through it a few more times and then take a look."

He took the paper tape handed to him by Fang Xudong and wrote down the data on the width of the melting zone, the pushing speed, the temperature fluctuation, and the resistivity into the record book.

That notebook originally recorded all the furnace temperature tests conducted by the Institute of Physics. Most of the data on the pages came from manual pressure adjustment and old-fashioned pyrometers. Now, Jiang Ming saw that Huang Kun had appended the curve of 502 to the end, and marked the number of the 502 technical group next to it.

This is the first time that two sets of test records have been put into the same book.

"We did it six times in a row without changing the parameters," Jiang Ming said. "After each run, we measured the resistivity and plotted the curve of impurity redistribution."

Huang Kun looked up at him.

"After six repetitions, cut off the tail. Can the remaining part reach three nines?"

"Based on the data from the first test, there is a chance that the front end will exceed the threshold. The specific result will depend on the stability of the melting zone and the degree of enrichment at the tail end."

"The word 'opportunity' alone is not enough to just write in the report."

"Then write in the curves six times."

Huang Kun looked at him and tapped the edge of the notebook twice with the pencil in his hand.

"Do it according to this standard."

In the afternoon, the second purification process began. Lao Sun locked the feed rate at 0.8 millimeters per minute, Fang Xudong adjusted the paper tape speed, Lin Lanying was responsible for the resistivity retest, and Jiang Ming stood in front of the control panel to observe the temperature difference compensation.

The melting zone in furnace No. 3 shifted again, and the bright color on the surface of the germanium rod moved backward along the coil, while the changes left from the first pass were covered by a new crystalline layer.

As the curve gradually stabilized, Fang Xudong said, "After completing six cycles, the next step is to perform single crystal growth."

"Director Wu is already preparing for the modification of the single crystal furnace."

"The material is remelted after regional purification, and then the seed crystal is allowed to touch the surface of the melt. It is then slowly lifted, and the liquid solidifies along the direction of the seed crystal."

Old Sun chimed in from the side, "How do you spin the seed crystal?"

Jiang Ming looked at the process card, his gaze falling on the column for seed crystal rotation speed. He crossed that line with his pencil, leaving a light-colored mark on the paper.

"This still lacks empirical data."

Fang Xudong put the record sheet away and didn't ask any further questions.

Inside the furnace, the second round of fusion was still underway. The pressure gauge pointer on the outside of the quartz tube remained stable, and the temperature control system kept the melting zone firmly within the predetermined length.

The real challenge has shifted from whether it can be purified to whether a usable single crystal can be grown.