Re: strength of vacuum

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 

Or, do what we do at work for thermal vac and vacuum breakdown tests on
spacecraft and flight hardware, and use a BIG, fast pump.  Then the pumping
speed is high enough that the outgassed atoms/molecules are pumped out as
soon as they manage to bounce into the pump.If you've got 48" throat diff
pumps and truckloads of LN2, you can be pretty cavalier about stuff..  Even
so, pumpdown takes many hours.

However, Ken's comments are very much to the point. If you've got a 3 or 4"
turbo, you're going to be waiting a good long time to pump down even a small
tabletop coil to better than a micron, and that's just getting started.

If you're serious about high vacuum, vapor degreasing is your friend.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, November 01, 2003 9:04 PM
Subject: Re: strength of vacuum


 > Original poster: "Crow Leader" <tesla-at-lists.symmetric-dot-net>
 >
 > That's a hard vacuum, and from what I'm being told, pretty hard to get.
The
 > vacuum pro I chatted with (I got a difusion pump to make tubes at home)
said
 > you need to bake out anything you are evacuating for hours, use materials
 > that don't outgas, have correct diameter tubing to your pump, and you may
 > still never get a vacuum anywhere near the rating of your pump. Unless all
 > your parts are glass/ceramic and metal, you won't get a vacuum that hard
 > anyways.
 >
 > KEN
 >
 >
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Friday, October 31, 2003 12:41 PM
 > Subject: strength of vacuum
 >
 >
 >  > Original poster: "RIAA/MPAA's Worst Nightmare"
<mike.marcum-at-zoomtown-dot-com>
 >  >
 >  > I was thinking of encasing my big HV stuff/tesla coil in vacuum as
opposed
 >  > to oil (heavy in 15+ gallon quanities). Anyone know what the dielectric
 >  > strength of  a 1.5x10E-7 micron vacuum is? Is there a formula to
calculate
 >  > it from a known micron level (below the glow discharge region of 1-1000
 >  > microns)? This is the lower limits of my 2-stage rotary/turbomolecular
 >  > setup (probably the only way to get a better vacuum is to go out into
 >  > interstellar/intergalactic space and open a jar). I was also going to
make
 >  > some vacuum pulse caps (RF lossless and nearly indestructable other
than
 >  > from a vacuum leak), but with a k of 1, I need to get the plates as
close
 >  > as possible for a given voltage.
 >  >
 >  >
 >  >
 >
 >