What is the sealing mechanism of UHV view ports & electrical interconnects?

In summary, Knife edges on the edges of flanges with a maleable material gasket like copper is often used for creating UHV chamber environments. The UHV seal is maintained by using ceramics bonded to a metal surface which is then welded into the chamber using vacuum compatible techniques.
  • #1
Questii
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Knife edges on the edges of flanges with a maleable material gasket like copper is often used for creating UHV chamber environments.

For UHV view ports, typically say quartz or some other material, how is the UHV seal accomplished?

Is it the same mechanism? E.g. knife edges machined on quartz windows and then encapsulated by two UHV chamber 'rings/flange cover' with a gasket inbetween the two mating surfaces?

What about electrical interconnects/feedthroughs? How do you seal them to create UHV (and still create electrical insulation because UHV chambers are often metal and you can't generally use polymers because of outgasing)? Do they use ceramics between the metal connects and the chamber or high purity polymers/epoxy like polyimide?

How is the UHV seal maintained for electrical feedthroughs also?
 
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  • #2
Questii said:
Knife edges on the edges of flanges with a maleable material gasket like copper is often used for creating UHV chamber environments.

For UHV view ports, typically say quartz or some other material, how is the UHV seal accomplished?

Is it the same mechanism? E.g. knife edges machined on quartz windows and then encapsulated by two UHV chamber 'rings/flange cover' with a gasket inbetween the two mating surfaces?

What about electrical interconnects/feedthroughs? How do you seal them to create UHV (and still create electrical insulation because UHV chambers are often metal and you can't generally use polymers because of outgasing)? Do they use ceramics between the metal connects and the chamber or high purity polymers/epoxy like polyimide?

How is the UHV seal maintained for electrical feedthroughs also?
http://en.m.wikipedia.org/wiki/Glass-to-metal_seal

browsing through these vacuum system
Threads, I found this unanswered question, and thought I would contribute information I found on Wikipedia
 
  • #3
Electrical feedthroughs use ceramics bonded to a metal surface which is then welded into the chamber using vacuum compatible techniques.

The ceramic-metal bonding is similar to glass-metal bonding.

Obtaining materials with similar coefficients of thermal expansion is mandatory, or else the seal will fail when the chamber is heated for de-gassing.

You can find more details here: http://www.mdcvacuum.com/DisplayContentPage.aspx?d=MDC&cc=33c1ded3-4381-4d1b-8eed-bd5622ccaa5f
and here: http://mpfpi.com/
 
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  • #4
...

Obtaining materials with similar coefficients of thermal expansion is mandatory, or else the seal will fail when the chamber is heated...

yes and I understand similar coefficient of thermal expansion is required simply for the manufacturing process.

Dissimilar cte will cause the bond to fail as the newly fabricated part cools(!
 

1. What is the purpose of a UHV view port?

A UHV (ultra-high vacuum) view port is used to visually observe the inside of a vacuum chamber while maintaining a high level of vacuum. This allows for monitoring of experiments or processes taking place inside the chamber.

2. How does a UHV view port maintain a vacuum seal?

A UHV view port typically consists of a window made of a high-strength material, such as sapphire, which is sealed onto the vacuum chamber using an O-ring or metal seal. The window is also often surrounded by a metal frame to provide additional support and stability.

3. What is the difference between O-ring and metal seals for UHV view ports?

O-ring seals are made of a flexible material, such as rubber, and are commonly used for lower vacuum levels. Metal seals, on the other hand, are made of a harder material, such as copper or stainless steel, and are used for higher vacuum levels. Metal seals provide a more reliable and durable seal, but can also be more expensive.

4. How are UHV electrical interconnects sealed?

UHV electrical interconnects are typically sealed using a combination of metal seals and feedthroughs. The feedthroughs are inserted through the vacuum chamber wall and sealed using metal seals, while the electrical connections are made through the feedthroughs using specialized connectors or pins. This allows for the transfer of electrical signals into and out of the vacuum chamber without compromising the vacuum seal.

5. Can UHV view ports and electrical interconnects be used in extreme environments?

Yes, UHV view ports and electrical interconnects are designed to withstand extreme environments, such as high temperatures and pressures, as well as corrosive or radioactive materials. They are often used in industries such as aerospace, semiconductor manufacturing, and nuclear energy research.

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