Basics of Vacuum Technology

Several instruments in our lab work in vacuum environments. For example

  • E-beam evaporator
  • Graphene growth system
  • Optical cryostat

If using these systems, there are some basics about vacuum technology that you need to know. Our lab has a copy of “A User's Guide to Vacuum Technology” by John O'Hanlon. This book is an excellent resource.

I'll collect a few classic “rules of thumb” on this wiki page:

  • Mean free path in mm = 6.6/P

Where P is the pressure in Pascals. (1 atm = 10^5 Pa = 760 Torr).

PressureMean free path
760 Torr65 nm
7.5 x 10-6 Torr6.6 m
Standard leak testing procedure: The vacuum chamber is pumped out. A residual gas analyzer (RGA) is attached directly to chamber. The researcher sprays He gas on different cracks in the system. The RGA beeps if He gas enters the vacuum chamber.

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