Residual Gas in High Vacuum Systems

In summary, the likely main residual gas constituent of a high vacuum system is hydrocarbons, which come from rotary pumps. To achieve ultra-high vacuum, the vacuum can be improved by using techniques such as cryopumping and baking. The likely main residual gas constituent of ultra-high vacuum is typically water vapor or other trace gases.
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Ryomega
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Homework Statement



What is the likely main residual gas constituent of a high vacuum system (HV) (P~1x10-4 Pa) and where does it come from? Explain how the vacuum may be improved to give ultra-high vacuum (UHV) (P~1x10-8 Pa). What is the likely main residual gas constituent of ultra-high
vacuum?

The Attempt at a Solution



My first guess was hydrocarbons for HV, but apparently that's something that occurs in rotary (rough) pumps which goes to about 10^-1 Pa.

I've searching google with no answer to this particular question.

Would anyone like to share their thoughts or a link with some answers?

Thanks a lot.
 
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Related to Residual Gas in High Vacuum Systems

1. What is residual gas in high vacuum systems?

Residual gas in high vacuum systems refers to the small amount of gas molecules that remain in a vacuum chamber even after the majority of the air has been removed. These residual gas molecules can have an impact on the quality and stability of the vacuum within the system.

2. Why is it important to minimize residual gas in high vacuum systems?

Minimizing residual gas is important because it can affect the performance and accuracy of experiments or processes taking place within the vacuum system. Residual gas can also lead to contamination, which can be detrimental to sensitive equipment or materials.

3. What are the common sources of residual gas in high vacuum systems?

The most common sources of residual gas include outgassing from materials used to construct the vacuum chamber, leaks in the system, and residual gas trapped in the pumping system. Other sources may include atmospheric contamination, desorption from surfaces, or gas released from chemical reactions within the system.

4. How is residual gas measured in high vacuum systems?

Residual gas can be measured using a residual gas analyzer, which is a device that can detect and quantify the types and concentrations of gas molecules present in the vacuum chamber. This measurement is typically expressed in terms of pressure, such as millitorr or parts per million (ppm).

5. What techniques are used to reduce residual gas in high vacuum systems?

There are several techniques used to reduce residual gas in high vacuum systems, including proper material selection for construction, proper sealing and cleaning of the vacuum chamber, and using high-quality vacuum pumps. Other techniques may include baking the vacuum chamber to remove any trapped gas, purging the system with inert gases, or using cryogenic traps to capture and remove residual gas molecules.

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