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: Abandoned vacuum chamber
Date: Oct 10, 2:30 pm
Poster: Richard Hester

On Oct 10, 2:30 pm, Richard Hester wrote:

I am reminded of a cryptic sign that has hung above a foundry in Oakland, CA neart he freeway for years on end, saying "stop casting porosity". Castings have problems with voids, pits, slag inclusions,just as Mr. Hull mentioned. Aluminum is a second best vacuum material for reasons of porosity. SS (304 or 316) is the best if you can afford the fittings. If conflat flanges are out for reasons of cost, you may want to consider ISO or ASA flanges, which are more reasonable, though rated for only HV rather than UHV. A friend with a machine shop can probably gin up an arrangement like an ASA flange without too much trouble. Check the K.J. Lesker catalog for examples of the flanges I mention.
Richard Hester

>> Anyway what I would like to know is if anyone can come up with any lookouts or problems with the idea. I was considering either phosphor bronze or a corrosion resistant aluminium but i don't know how they perform in a vacuum with regard to outgassing/vapours etc.
>The phosphor broze would be out due to out gassing (Zinc) and micro pits. Aluminum is OK for the most part, but with casting, you are always prone to piting and gas inclusions throughout the piece.
>I would really go with extruded or spun hemispheres.
>Richard Hull