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Re: Vacuum Pumps, can it be good AND cheap?

Posted: Fri Mar 09, 2012 8:08 pm
by Rob Pope
I read that the lowest pressure attamiable with a 1399 is 1.5X10^-2 torr, this translates to 15 millitorr, or ~15 microns, correct?

I just want to make sure this pump will be capable of fusion pressures

Re: Vacuum Pumps, can it be good AND cheap?

Posted: Tue Mar 13, 2012 3:23 pm
by Richard Hull
Any mechanical pump is generally not ideal for fusion, regardless of low end claims. You have to have a secondary diffusion or turbo pump for easy fusion.

The 1399 specs are, for the most part, a joke and, even if real, those specs are for a brand new, off the shelf, mint pump! An old worn out single stage like the 1399 would never do spec. As a matter of fact, few brand new mechanical pumps will meet their manufacturers spec in a real, full vacuum system setup.

The only thing that's real and honest is your pump of choice, pulling through your system, being read by a well calibrated gauge. All else is pretty much sales pitch and floobie dust.

Get a two stage pump and pray it is OK.

Richard Hull

Re: Vacuum Pumps, can it be good AND cheap?

Posted: Wed Mar 14, 2012 8:25 am
by AllenWallace
Call or visit every neon sign shop and also every testing lab that does helium leak detection.
Explain that you are doing a high school science fair project and can you have a old pump ?

I got my most excellent welch 1397 pump from a discarded helium leak detector. It pulled the fusor down to plasma extinction very easily.

FYI, when talking to the shop owners, avoid discussing fusion or neutrons or radiation-- it just make them think you are not serious or you are doing something dangerous. You might call it a high vacuum deuterium plasma experiment.

Re: Vacuum Pumps, can it be good AND cheap?

Posted: Wed Mar 14, 2012 6:26 pm
by Rob Pope
Thanks for the advice both of you
I'll start looking for other types of pumps, and keep my eye out for good dual stages

Re: Vacuum Pumps, can it be good AND cheap?

Posted: Fri Mar 16, 2012 1:24 pm
by Rob Pope
OK, I've come to understand how a good vacuum system is created, and that I need an oil diff pump (turbopump seems excessive)
I found this http://www.ebay.com/itm/Edwards-High-Va ... 3a70d29b51
some questions / concerns about this type of pump

1 it's watercooled, i can set up a watercooling system no problem, is that OK?
I know that most fusors prefer air cooled

2 I see no mounting flange... how difficult will this be to mount?

3 I see no visible baffle, will I need to install one?

I'm planning on a bell jar setup, similar to what Jeff Robertson has here- viewtopic.php?f=10&t=4156#p26546