In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.
Subject: Re: Sorption Pumps
Date: Jan 19, 3:08 pm
Poster: Richad Hull
On Jan 19, 3:08 pm, Richad Hull wrote:
>What about air aspirators? I wasn't planning on using a water aspirator for exactly the reasons you cite. In any case they are much much much cheaper than mechanical roughing pumps. While they can only go to about 20 torr, a sorption pump can take over from there and go deep.
Air aspirators are fine.
I really forgot to mention that in a three pump system, the first pump might need bakeout after every draw down from air.
Pump number 2 might only need bakeout once every 10-20 air pump cycles and pump 3 might last a year or more between required bakeouts. The great thing is that once sealed off, your chamber pressure which might rise due to outgas or rise slowly due to virtual or even real micro leaks, can quickly be returned to deep vacuum by LN2ing the third pump and opening its valve to the chamber only!! Nice.
I do this with the micromaze and glow cleaning often with fusor III, and never even crank up the mechanical pump. I have the system sealed, finally, to the point where after 3 weeks the pressure is only back up to 50 microns and glow cleaning and opening the valve to the micromaze can have it back down to submicron pressures in minutes.
Good luck with your efforts.
- Re: Sorption Pumps/LN2 & Pump mods - Stephen Jan 19, 3:44 pm