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, 6:16 pm
Poster: Pierce Nichols

On Jan 18, 6:16 pm, Pierce Nichols wrote:

>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'm attracted to sorption pumps b/c it appears that an effective sorption pump can be ginned up out of copper tube and pipe fittings, along with some copper flashing as internal fins. LN2 can be a bit of a pain, but it's not all that expensive. The valves are expensive, but they can be smaller valves, and I think I can use the aspirator or at least a small, cheap pump for the bakeout of the sorption pumps.

>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.

I sort of figured that. I'm hoping that I can set up my fusor arrangement initially such that I can pump the SOB down and leave it there for long periods. Not entirely likely, given how often I like to change my mind *g*.

> 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.

Can you describe the bakeout cycle, please? Do you think it's possible to bakeout with an aspirator sucking up the exhausted vapors?