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 |
 | 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. |