Diffusion Pump Backing/Roughing Operation Order
For operating a diffusion pump with a valve between backing and roughing, which order do I follow:
1st Order:
- Set MANIFOLD VALVE to roughing and Pump down Vacuum chamber to 2mTorr
- Switch MANIFOLD VALVE to backing and pump air from diffusion pump then heat it for 20 minutes
- Open diffusion pump valve to chamber to enable diffusion pump
2nd Order:
- Pump down Diffusion pump to Backing and pump down to 2 mTorr
- Switch MANIFOLD VALVE to Roughing and pump down Vacuum chamber till 2 mTorr
- Switch MANIFOLD VALVE back to Backing and start heating process for 20 minutes
- Open diffusion pump MAIN VALVE to chamber to enable diffusion pump
I know the image shows that the roughing cycle is in the beginning but wasn't sure if it is beneficial, necessary, or bad to pump down diffusion pump in backing first. Also in the image of my vacuum chamber, I believe that is the MAIN VALVE, and it doesn't exactly look like an airtight seal so maybe roughing is just the way to go. The Manifold valve is an air tight seal though. I'm just being overly precautious before I turn on diffusion pump for the 1st time.
