94: From Technological Warfare to Space Empire

Chapter 123 It doesn't make sense, this should be a success!

During this period, Lin Yu practically lived in the laboratory.

It was drizzling in Beijing that day.

In the laboratory, Lin Yu listened to the students' reports with a frown.

How many atoms are there?

A student surnamed Fang stared at the signals on the experimental equipment and answered in a flustered voice.

"It's less than 10 to the power of 7, which is two orders of magnitude less than the 10 to the power of 9 we need."

Lin Yu walked to the vacuum gun and looked inside through the window.

A few faint lights drifted in the vacuum.

Like fireflies flying around aimlessly.

According to theoretical calculations, this magnetic field gradient and this laser efficiency should be able to capture at least 10 to the power of 9 atoms.

What is the laser frequency detuning?

The student in charge of lasers answered.

"Red out of tune by 10 megahertz".

Lin Yu was silent for a few seconds. The laser frequency was correct, the magnetic field gradient was correct, and the vacuum rate was correct.

Where else could the problem lie?

This shouldn't be happening; this shouldn't have come to this.

He hadn't personally conducted this experiment either.

Now we can't find out where the problem is at all.

I waited until the afternoon.

The temperature in the laboratory was getting hotter and hotter.

Lin Yu initially thought his breathing difficulties were due to anger over the unsuccessful experiment.

But now that I'm slowly realizing it, something doesn't seem right.

"Cooling the coil!"

"How do you cool your coils?"

The group of students looked at each other and then answered somewhat blankly.

"Natural cooling works well for copper wires."

Lin Yu walked around the optical platform and finally arrived at the pair of anti-Helmholtz coils.

This is the solution Professor Yang provided.

The coil is made of oxygen-free copper, and each turn is wound neatly.

Lin Yu got closer and felt the temperature rise even higher.

"No, with a current of 10 amps, a coil resistance of 0.5 ohms, and a heating power of 50 watts, how high would the temperature rise if it were to cool naturally?"

He quickly made a mental estimate.

"According to the temperature coefficient of resistance of copper, the resistance increases by 4% for every 10-degree increase in temperature."

"Increased resistance leads to greater heat generation, creating a vicious cycle."

"The temperature of the coil is now at least 30 degrees Celsius higher than room temperature."

"The magnetic field gradient will be 15% lower than the design value."

The students looked at each other, none of them having noticed this detail.

Lin Yu squatted down and began to inspect the cooling water pipes.

"Connect a water-cooling solution."

Everyone worked all night.

When the temperature was controlled within ±0.5 degrees using circulating water cooling, the signal on the oscilloscope surged by an order of magnitude.

Although it hasn't reached 10 to the power of 9 atoms yet. Currently, it only has 10 to the power of 8 atoms.

But at least the direction is right.

We worked on it for a few more days.

Various problems have arisen.

Either the background air pressure was too high, resulting in too short a period of confinement.

Finally, by replacing the vacuum chamber with a titanium alloy vacuum chamber from Shenyang Aircraft Corporation, the number of atoms was finally increased to 10 to the power of 9.

Either the laser frequency is unstable.

The output frequency of the Ti:Sapphire laser is wildly inaccurate.

It deviates directly from the resonance line of the rubidium atom.

But no one had touched it yet. After checking several times, it was discovered that it was because it was approaching April and the weather was getting hot.

The air conditioning in this old building works well, but the insulation is poor.

Temperature differences caused the frequency of the Ti:Sapphire laser to shift.

In the end, Lin Yu went back and frantically researched the data, and came up with a saturated absorption frequency stabilization system, which finally stabilized the output peak.

After all this turmoil, it's already mid-April.

BJ's spring came incredibly fast.

The coconut trees outside the window were already covered with green leaves, but no one in the lab was in the mood to look at them.

They wished they could seal all the windows shut and leave the lights on inside.

After compression in a magneto-optical trap and cooling via polarization gradient, the process is carried out step by step.

The temperature of the atomic cloud has dropped to around 10 microK.

Now, with just one more step of evaporative cooling, BEC can be fully achieved.

"The radio frequency field is scanned from 20 MHz to 2 MHz, with a scan time of 5 seconds."

Lin Yu stared at the image of atomic clouds projected onto the screen.

Try to keep your voice as calm as possible to reassure the crowd.

But my palms were already sweating.

This was the closest we've ever come to success.

No one present, including Academician Zhou, could have predicted that the BEC experiment would progress so quickly in just a few weeks.

Now, at best, they can't reduce it by a few thousand micro-openings.

But now we are very close to the required 170 nanokJ.

Ten micro open is one thousand nano open.

As long as the evaporative cooling process continues to lower the temperature—

Then the Chinese will soon be able to complete the BEC experiment for the first time.

Everyone in the audience was trembling.

The people who came to the laboratory were not just Academician Zhou and Lin Yu's team.

The higher authorities sent people to inspect the area several times.

Chief Hou sent a large group of people to surround the Chinese Academy of Sciences building.

Not to mention birds, even flies can't get out.

Many senior experts also joined the research, including Professor Yang.

Everyone knows this is really important.

One step forward, and the rain will stop and the sun will shine.

After Lin Yu issued the command.

Professor Yang's fingers, hovering over the keyboard, pressed the Enter key.

Only after he finished knocking did he have time to take a deep breath.

The atomic cloud on the screen began to change.

As the radio frequency decreases.

The highest-energy atoms were gradually expelled from the trap.

The core of the atomic cloud became increasingly dense and brighter.

Everyone held their breath and stared at the screen.

When the frequency drops to 5 MHz, the cloud density of the atomic cloud is already astonishingly high.

Under normal circumstances, signs of condensation should be visible.

But now there's nothing.

The atomic cloud has indeed become denser, but it is still a normal hot atomic cloud without the sharp peaks characteristic of BEC.

Lin Yu frowned.

"Keep scanning."

The frequency kept decreasing: 4 MHz, 3 MHz, 2 MHz.

But even after the scan was completed, the atomic cloud remained still on the screen, showing no abnormalities.

Lin Yu frowned as he watched; this wasn't right, it shouldn't be like this.

Logically speaking, even if it fails, there should still be some changes.

Professor Yang muttered to himself.

"Failed? That shouldn't be the case."

"We've never gotten this far before!"

"The density is sufficient, the temperature is sufficient, so why can't it be done?"

Lin Yu stared at the screen, his mind racing.

The principle of evaporative cooling is correct, and the parameters are calculated according to theory.

Moreover, every step we took before has proven to be correct over time.

This step shouldn't have too much error either.

But why didn't it condense?

He walked to the optical platform and stared at the coil of the magneto-optical trap for a very long time.

Once again, I recalled the previous theories.

The hot atoms rise.

Cold atoms descend.

The magnetic field strength of the magneto-optical trap at the bottom is 0.

This ensures that the atoms won't move around randomly.

"What about the zero point of the magnetic field?"

"Check the zero point of the magnetic field!"

The professors were stunned.

"The central magnetic field of the magneto-optical trap is 0."

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