Hand rubbing nuclear fusion live in the wilderness

Chapter 462 Ultra-Low Temperature Freezing

The grinding process of the beryllium-iridium alloy mirror is still going on.

It is a little different from the polishing of the previous CNC equipment. The previous beryllium-iridium alloy mirror was fixed vertically in the CNC equipment, but this time it is lying down.

The alloy mirror lying flat on the machine tool has a slight curvature, and the slightly concave central area is filled with gray polishing fluid, like mercury, reflecting a faint metallic light.

This is a special polishing liquid for the final polishing of beryllium-iridium alloy mirrors. The main components in it are silicon ions + ultra-precision nano-scale alumina powder.

And directly above the mirror, a mechanical arm hangs down. Below the mechanical arm is an arc-shaped disc, which is constantly smoothing and polishing operations.

This is the polishing equipment for subsequent processing of beryllium-iridium alloy mirrors.

Using this equipment with the numerical control program, coupled with the precise infrared light measuring instrument, can achieve low-nanometer mirror polishing.

Although it is not comparable to the large polishing equipment in the CNC factory, it is enough for the beryllium iridium mirror used in the test.

Processing from the mirror surface roughness of the [-]nm level to the [-]nm level, this process takes longer than the Korean Won expected.

Even if the polishing equipment can operate 24 hours a day, and can automatically adjust the polishing angle and replace the polishing disc, it still took four and a half days.

And this is just processing a mirror with a diameter of only [-] centimeters. If it is replaced with a formal large mirror, the polishing time may increase exponentially.

The mirrors used on space telescopes are not simply polished with a grinding disc.

These mirrors with a certain curvature arc in the design, not only the surface roughness error cannot exceed five nanometers, but also the arc error of the mirror surface must be simultaneously accurate to the nanometer level.

Because it needs to reflect the received infrared light to the central signal receiver.

In addition, the most important thing is that these mirrors used in space telescopes can be said to have completely different curvatures of each mirror.

This means that batch processing is completely unacceptable. He needs to write a corresponding CNC processing program for each mirror surface separately, and write a data model to control the polishing equipment to achieve precise processing.

This is a rather troublesome thing.

Otherwise, how can we say that the space telescope is something that only superpowers can afford?
After nearly five days of tossing, the first piece of beryllium-iridium alloy mirror surface used in the experiment was finally polished.

This is the audience in the live broadcast room, and it is also the first time that Han Yuan has seen an object with a surface roughness of five nanometers.

Even experts from various countries squatting in the live broadcast room, I am afraid it is the first time to see a mirror with this level of smoothness.

After all, with the current polishing technology of human beings, the highest mirror surface polished by hand is at least about ten nanometers.

The Webb telescope is a top-level metal mirror, and its mirror roughness, that is, the surface finish, is only 14 grades, and the Ra index is 0.012.

Ra here refers to microns, 0.012 microns, which is 12 nanometers.

This is almost the limit of human manual polishing.

If the beryllium-iridium alloy mirror surface is manually polished and polished, let alone whether it can reach the five-nanometer level, the polishing time alone needs to add a zero at least.

Without a month or two, it can't be polished at all.

However, polishing with an ultra-precision polishing machine can save at least ten times the time.

It can be seen that technology is really the primary productive force.

After changing his clothes, putting on his shoe covers, and cleaning himself completely, Han Yuan entered the ultra-clean and dust-free room.

The beryllium-iridium mirror that has been polished and processed is now held in mid-air by the edge part of the mechanical arm.

Standing in front of the mirror, Han Yuan carefully observed the beryllium-iridium alloy that had undergone the second grinding and polishing process.

If you simply observe it with your eyes, there is no difference between the mirror surface roughness of the five-nanometer level and the twenty-nanometer level, at least he can't see any difference.

To detect the roughness of this level of mirror surface, special instruments are required.

At the same time, the audience in the live broadcast room also looked curiously at the beryllium-iridium alloy mirror in the display.

[It seems to be the same as before? 】

[It's the same as before it was processed, but this processed an air? 】

[It is [-] nanometers before processing, and it is [-] nanometers after processing. There is no difference. 】

[It's right if you can't tell the difference, because this is far beyond the scope of human vision, and human vision can't detect such a subtle difference at all. 】

[If you can see the difference, the country should arrest you to dissect it. The naked eye can see the five-nanometer level, tsk tsk, this is not human at all. 】

[I can't see any difference, but I feel like it's a little brighter? 】

[Five-nanometer mechanical polishing is terrifying! 】

[I checked a few days ago. If we don’t use this anchor’s technology, the highest precision we can polish is ten nanometers, and it’s purely manual. Mechanical polishing can only be processed to thirty nanometers. 】

[Upstairs, you said the opposite, hand-polished ten nanometers, and machined thirty nanometers? 】

[It’s true, the mirror surface of the previous Webb telescope was on the order of ten nanometers, which was hand-polished bit by bit by polishing engineers. 】

[In the field of polishing, in the past, machinery was really inferior to manual work. Manual polishing can achieve any precision you require. However, after this anchor produced a top-notch polishing machine, manual polishing was retired. 】

[Manual polishing can achieve ten nanometers, which is really awesome. How many years of practice will it take to control with such precision. 】

[The 'gunpowder engraver' in our country is even better. They can control the error of gunpowder by hand to within 0.1 mm, which is thinner than a strand of hair. 】

Looking at the barrage, Han Yuan smiled.

In top-level polishing, engraving and other fields, what can be done by machinery can basically be done by hand, and what cannot be done by machine can sometimes be done by hand.

In these fields, Huaguo has produced many touching deeds and master-level figures.

However, with the development of technology, it is inevitable that one day the precision of manual engraving and polishing will not be able to keep up with that of machinery.

Five-nanometer beryllium-iridium alloy mirror processing is an insurmountable moat for polishing engineers in the real world.

Even the polishing engineers who processed the mirror surface of the Webb telescope could not achieve this level.

Unless, like him, he has been injected with human development medicine.

For now, he can still achieve five-nanometer polishing, but he is not without limits.

Although there is no specific test, but Won estimated himself, the limit is probably around five nanometers.

No matter how low it is, he can't guarantee that the flatness of the mirror surface will always be consistent.

After completing the preliminary inspection of the beryllium-iridium alloy mirror, Han Yuan put on gloves, carefully trimmed the edge of the main alloy mirror, removed it from the mechanical arm, and sent it into the cryogenic instrument.

The beryllium-iridium alloy mirror used for infrared reflection sensing will eventually need to be sent into ultra-low temperature space, and it needs to maintain a low temperature below minus [-] degrees for a long time.

Therefore, it is indispensable to carry out ultra-low temperature freezing test on it.

The South Korean won needs this beryllium-iridium mirror to maintain its own shape in an ultra-low temperature environment below minus 230 degrees without any deformation, or to keep the linear expansion system below 0.0000004.

Only in this way will it not affect the reflection and sensing performance of this beryllium-iridium alloy mirror to infrared light.

The ultra-low temperature instrument was activated, and the temperature inside dropped rapidly. Through the sensor, Han Yuan observed the situation inside.

The falling temperature curve indicated that the temperature inside the ultra-low temperature instrument was steadily decreasing, and soon, the temperature had broken through minus one hundred degrees.

After confirming that the temperature drop was normal, Won turned to look at the inspection data of the beryllium-iridium alloy mirror.

Through the chart data displayed on the screen, you can clearly know the state of the alloy mirror inside the cryogenic instrument and the corresponding infrared reflection data.

After browsing the chart data and confirming that the beryllium-iridium alloy mirror did not show any shrinkage at minus one hundred degrees, he continued to lower the temperature.

Minus one hundred degrees is cold enough, but it is not the ultimate goal.

This piece of beryllium-iridium alloy will eventually face the test of an ultra-low temperature of minus 230 degrees. Even if it remains normal at this temperature, it will face lower temperatures to test its performance.

Of course, the follow-up lower temperature detection requires him to complete the overall experiment and confirm that the beryllium-iridium alloy can be used as the mirror of the space telescope before doing it.

Now complete the test at minus 230 degrees and confirm that there is no problem with the beryllium-iridium alloy at this temperature.

As time goes by, the temperature in the cryogenic instrument decreases little by little. The lower the temperature, the higher the overall requirements for the equipment, and the slower the temperature decrease.

If it takes 5 minutes to drop from zero to one hundred degrees, then it takes at least three to ten minutes to drop from minus one hundred to minus two hundred.

Lower it any further, and it will take longer.

It is not easy to create an ultra-low temperature environment of more than minus 200 degrees.

Not only do you need to create an insulated space with a super-high thermal insulation capacity, but you also need to use special cooling methods.

Although the refrigeration principle is similar to household refrigerators, the coolant is not Freon, 134A or something.

But liquid nitrogen.

After passing through high pressure, nitrogen will release a huge amount of heat when it is condensed into a liquid state, and when it is vaporized under reduced pressure, it can absorb a lot of heat, thus creating a low temperature environment of more than minus 100 degrees, close to minus two hundred degrees.

However, liquid nitrogen refrigeration also has drawbacks.

That is, it cannot break through its own temperature of minus 190 degrees.

If a lower temperature is required, another cooling method-laser cooling is added.

That's right, this method that sounds like it is used in medicine is actually applied to ultra-low temperature manufacturing.

The principle is based on thermodynamics.

Anyone who has studied physics in junior high school knows that the thermal energy of an object is caused by molecular vibrations. The more intense the molecular motion, the higher the temperature.

When all molecular motions of an object stop, the temperature of the object is absolute zero without external interference.

Laser cooling, on the other hand, counteracts molecular motions by using laser-generated fluctuations.When the molecular motion is reduced, the temperature is naturally reduced.

In addition to this method, you can also use the most difficult to liquefy gas 'helium' to produce ultra-low temperature environment refrigeration.

Helium is quite difficult to liquefy, but its liquefied temperature is -269°C, which is very close to absolute zero.

Utilizing this feature, an ultra-low temperature space close to minus 250 degrees can be created.

But if it is lower, you still have to use laser cooling technology.

It took a while, but the temperature in the ultra-low temperature refrigeration equipment finally dropped to -230°C, which is the Korean Won's demand temperature.

Stabilizing the temperature at this data, Won looked at the display.

At a temperature of minus 230 degrees, the beryllium-iridium alloy mirror surface has a very slight linear expansion.

The linear expansion data is at -0.000000289.

That is to say, the length of beryllium-iridium alloy per meter is shortened by 0.000000289 meters, which is 289 nanometers when converted into nanometers.

This coefficient of linear expansion, completely within the standard index of 0.0000004, can be used in the manufacture of space telescope mirrors.

In addition to the linear expansion coefficient, there are two data indicators, the surface flatness and flatness of the mirror surface, which are particularly critical.

Because this involves subsequent hit reflections of infrared light.

The polished beryllium-iridium alloy mirror itself is not completely flat, but has a slight curvature.

This arc is different on every mirror surface, but is critical.

Korean Won needs to compare the mirror radian data that has just been processed with the mirror radian data below minus 230 degrees.

To confirm the changes in the radian data and the changes in the flatness and flatness of the mirror surface, so as to optimize the mirror and ensure that there is no problem with the subsequent large beryllium-iridium alloy mirror.

"There is an error in the radian, but the error is not large. The calculated data shows that the arc error is 0.0000108rad"

"As for the flatness of the lens, there are also errors, but the IRI index is 0.0000023m/km, and this difference is almost negligible."

Staring at the screen, Han Yuan checked the information fed back by various detectors in the ultra-low temperature refrigeration equipment, and muttered to himself to calculate various data, which made the audience in the live broadcast room look confused.

[I'm going, who can tell me what the anchor is talking about? 】

[Radian error, mirror flatness, these are all easy to understand. You can understand it from the literal meaning. As for the long string of zeros and rad units, you can just treat it as a small error. 】

[What is the nine digits after zero? 】

【Do it yourself! 】

[Nano, that is, every 1000 meters, there will be an error of 230 nanometers?This error is indeed negligible. 】

[Tsk tsk, this is minus 230 degrees, if a piece of iron is put in, it will shrink in half. 】

[Half is not, but the physical properties of iron will be changed, it will become very brittle, without any flexibility, and it will be broken into slag when it is hammered. 】

[So I really want to take a hammer and hit the platinum-iridium alloy in the video. 】

[It's beryllium-iridium alloy, come on, the word in front, follow me, pi==pi, beryllium-iridium alloy! 】

[Beryllium iridium alloy, referred to as p alloy, also known as 'fart alloy' in Chinese_]

【Chinese characters make you play badly】

(End of this chapter)