Search found 369 matches

by Quantum
Fri Jan 01, 2010 1:23 pm
Forum: Vacuum Technology (& FAQs)
Topic: Diff Pump Design
Replies: 7
Views: 2224

Re: Diff Pump Design

<t>That's exactly what I'm after, Derek.<br/> <br/> That would help me enormously.<br/> <br/> BTW, How is your Peltier cold trap design coming on?<br/> <br/> I'm interested in what device you plan to use, and how you intend to incorporate it into your system.<br/> <br/> I've asked this in the backst...
by Quantum
Fri Jan 01, 2010 12:31 pm
Forum: Vacuum Technology (& FAQs)
Topic: Diff Pump Design
Replies: 7
Views: 2224

Re: Diff Pump Design

<t>The only diff pumps I've seen for a reasonable price from the US recently were 11" ones. If I could find what I want, I'd buy it.<br/> <br/> We've established that 2" diameter is sufficient. Three stage, fractionating, water cooling, and a cold trap are the rest of my criteria.<br/> <br/> I'm sur...
by Quantum
Fri Jan 01, 2010 4:04 am
Forum: Vacuum Technology (& FAQs)
Topic: Diff Pump Design
Replies: 7
Views: 2224

Diff Pump Design

<t>I've spent considerable time over the Christmas period researching diff pump design, Steve Hanson's Bell Jar site has been useful, but so far, I've not yet come up with a design that satisfies all of my requirements.<br/> <br/> I've found several designs, with drawings, ranging from one inch sing...
by Quantum
Thu Dec 31, 2009 7:12 pm
Forum: Vacuum Technology (& FAQs)
Topic: Backstreaming
Replies: 25
Views: 6627

Re: Backstreaming

How do you plan to use the peltier device?

I've seen 12v 100w devices on E-bay. I suppose outgassing wouldn't be a huge problem in a foreline, but there must be other ways to utilize them?
by Quantum
Thu Dec 31, 2009 6:11 pm
Forum: Fusor and/or General Fusion Theory (& FAQs)
Topic: FAQ - The Sun versus the Fusor
Replies: 14
Views: 6022

Re: FAQ - The Sun versus the Fusor

<t>Richard, may I be the first to offer you the praise you so richly deserve.<br/> <br/> However, the other post to which you refer related to calculating the energy required to produce a plasma with a density similar to the core of the sun, thereby achieving thermonuclear conditions comparable to t...
by Quantum
Thu Dec 31, 2009 5:01 pm
Forum: Vacuum Technology (& FAQs)
Topic: Backstreaming
Replies: 25
Views: 6627

Re: Backstreaming

<t>Derek, there is still some backstreaming, according to Dow Corning, but they describe it as 'negligible'.<br/> <br/> You are also likely to have some backstreaming from the backing pump, unless it is a dry pump.<br/> <br/> This will contaminate the diff pump oil, and will result in backstreaming ...
by Quantum
Thu Dec 31, 2009 3:33 pm
Forum: Vacuum Technology (& FAQs)
Topic: Backstreaming
Replies: 25
Views: 6627

Re: Backstreaming

<r>From what I read, liquid nitrogen (or possibly liquid helium, which I understand is colder) is required to reduce backstreaming by a factor of 800, but water at 25 C will certainly reduce it, but not by as much.<br/> <br/> I've tried to get a link to an article on using Freon 22, to get down to n...
by Quantum
Wed Dec 30, 2009 7:28 pm
Forum: Vacuum Technology (& FAQs)
Topic: Anti-seize compound for 1/4-28 threads
Replies: 19
Views: 5873

Re: Anti-seize compound for 1/4-28 threads

The knife edges, mostly, I think, Derek. Apart from that, not a lot.
by Quantum
Wed Dec 30, 2009 7:26 pm
Forum: Vacuum Technology (& FAQs)
Topic: Backstreaming
Replies: 25
Views: 6627

Re: Backstreaming

<t>Yes, Derek, but most diffstacks seem to have a cryo-trap fitted, and most of us don't have liquid nitrogen on tap, although I've been reading up on some refrigerated ones, using fridge/freezer components and freon. It's possible to get to -50 centigrade, or lower. This isn't as good as around -20...
by Quantum
Wed Dec 30, 2009 4:26 pm
Forum: Vacuum Technology (& FAQs)
Topic: Backstreaming
Replies: 25
Views: 6627

Re: Backstreaming

<t>Modern Vacuum Practice by Nigel Harris (former head of training at Edwards) is a very informative book, with a large chapter on diff pumps, and quite a bit on backstreaming. It even differentiates between backstreaming and back migration.<br/> <br/> "Backstreaming is the direct flight of vapour m...