====== 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).

^Pressure^Mean free path|
|760 Torr|65 nm|
|7.5 x 10-6 Torr|6.6 m|


|{{::leak_testing.jpg?400|}}|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.|