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: Vacuum Alternatives
Date: Aug 22, 7:38 pm
Poster: Enon Harris

On Aug 22, 7:38 pm, Enon Harris wrote:

>Might there not be alternatives to high-cost vacuum pumps as means to an end? ...

>I've noticed that compressors usually cost considerably less than vacuum pumps...

>Also, why not use some kind of cryogenic means to condense the air within a vacuum chamber to the liquid state, at which point it would then be pumped out?

This isn't something Iíve tried personally, but back in the late 50s- early 60s Scientific American published a book of Amateur Scientist projects, one of which was an electrostatic linear accelerator which could produce from 100kEv to over 1MEv. The project included details of construction for a homemade high-vacuum pump that used a refrigerator compressor running in reverse as the first stage and a complicated blown-glass mercury vapor pump as the second stage. This setup would be dangerous if the glass failed in any way- an implosion enclosure is part of the book's plans, but mercury contamination might be worse. Today one could also add a liquid-nitrogen cooled zeolite getterer or an ion trap to the mercury pump for higher vacuums. (Or whatever the proper things are called- not my area of knowledge.) It is my understanding that only the highest stages of HV pump systems are best located in the vacuum chamber (traps rather than real pumps).