Fusion Message Board

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 18, 4:26 pm
Poster: Richard Hull

On Jan 18, 4:26 pm, Richard Hull wrote:

>"Designing Scientific Apparatus" alleges that you can pull 10^-7 torr in a properly baked chamber with a pair of properly prepared sorption pumps, in a system rough-pumped with a vacuum aspirator. Does anyone know how accurate a statement that is?

Extremely accurate!!

Prior to Turbo pumps, anybody who couldn't tolerate parts per billion of hydrocarbons in their vacuum, or who wanted the cleanest vacuum available, always used cryo-pumps (sorption pumps are of this school). You only need lots of valves ($$$)and lots of LN2 ($$$ + messey and a number of bothers and dangers) and you are off to the races and getting one of the best vacuums available.

I have seen these work and was just as impressed as I could be.

For regular amateur work, where you are up to air, pumped down and then back up to air, isn't the best application for sorption pumps. The bake out times of the sorptive materials are long and must be done carefully. This is even true of the micromaze which is a sorption seive without the cryogenic aspect.

Richard Hull

Richard Hull