Residual Gas Analyzer

31 03 2009

Just won this MKS Spectra Satellite RGA Residual Gas Analyzer w/Head. $800.

I got in touch with an MKS Technical Support Eng, and he is emailing the software to me.





Cleaning a Vacuum Chamber

29 03 2009

Found some information on cleaning vacuum chambers in this presentation on ultra high vacuum.

Some methods:

  • Bead Blasting    
  • Ultrasonic
  • Glow Discharge (top right)
  • Electropolishing
  • Reactive Gas Clean
  • Chemical (Acid and Alkaline)
  • Rough Abrasives

Cleaning method for 300 series stainless (Brookhaven National Laboratory)

  1. Degrease with ultrasonic agitation
  2. Hot alkaline pH 11
  3. wash with air agitation
  4. Rinse cold tap water
  5. Rinse DI water with air agitation
  6. Dry in hot air oven
  7. Vacuum bake at 950 C for 2h
  8. Glow discharge clean
  9. Reactive gas clean




Stop the Press

28 03 2009

Never Assume. 

So today I actually removed the top hexagonal part of the chamber from the bottom cylenrical part, and guess what I found.

The gasket on the lid is a different diameter than the gasket on the bottom cylender. Which means…

We can place the lid on the cylinder and it might just work.

 

Also 100th post!





Pump System

28 03 2009

Just won this Pfeiffer Balzer Turbo Molecular Pump TSU 065D PMS03407





On it’s side

28 03 2009

Stuart suggested turning the chamber on it’s side:

on_side

This would require a custom stand, but that’s easier to do than custom vacuum equipment. This also would require an adapter from the turbo pumps flange to the 10″ conflat (likely ~$500)

Also, not sure if the two 27″ OD ASA(rubber) flanges would work as well without the assistance of gravity. I image this setup would require a shipping strap when not under vacuum.

Also having a rounded bottom makes mounting things more difficult.





Turn the problem on it’s head

27 03 2009

What if we take the bottom cylinder of the vacuum chamber and flipped it upside down and used it like a bell-jar on top of a 316L stainless steel blank?

This would take the ASA (rubber) portal count from

7 X 14″, 2 X 27″

to

1 X 14″, 1 X 27″

This would require a custom fabricated blank, so while were are at it let’s add a flange for our turbo-molecular pump, in it’s ideal orientation:

upside_down2

 

I’m getting quotes on the custom 27″ blank.





Vacuum Gauge and Residual Gas Analyzer

26 03 2009

This chamber did come with a vacuum gauge, but it only goes down to 10E-3 torr, so it’s not suitable for our needs.

What we need is an Ionization gauge. I found one product that I really liked, the Intru Tech Hornet. It seems very easy to use: install conflat, plug in power, and get a reading. Coming in at under $1K, this gauge is in my budget. 

However, this is the scenario I imagine happening if I get this gauge: we get the pressure down to 10E-6 torr and that’s as low as it goes. At this point you need a Residual gas analyzer, to make any further diagnosis. If you see air, you have a real leak from the outside. If you see water you need a bake-out. If you see hydrocarbons, you have outgassing. I found the extorr,  which combines a Pirani, Ion Gauge, and RGA. It’s $3,450, and a stretch for my budget, but would be the only gauge you needed. It requires a windows box, and the software looks clunky.

Would an RSA also be useful for monitoring the pressure of the process gasses (deuterium/hydrogen/boron/helium)?








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