[time-nuts] Maser info (vacuum levels)
Mark J. Blair
nf6x at nf6x.net
Thu Sep 2 18:17:35 UTC 2010
On Sep 2, 2010, at 10:28 AM, Corby Dawson wrote:
> This EFOS maser typically runs with the two vacuum pressures below 1.5 X
> 10-6 Torr. (as measured via the ion pump current)
> Maximum should not exceed about 3.6 X 10-6 Torr for either pump.
> The internal vacuum will drop to about 1 X10-7 Torr if the Hydrogen to
> the disassociator is turned off.
Back in college, I took a semiconductor device physics course which included a lab where we made simple ICs (the most complex devices were SR latches). We had a vapor deposition system for plating on gold or aluminum, which pumped the chamber down below 10E-12 Torr as I recall, within ten minutes or so after a clueless freshman opened the beast up and tossed in a bit of aluminum or gold wire and a few chunks of silicon with their grubby hands (ok, we used tweezers, but still...). The whole unit was about as big as a refrigerator or two. It used a rotary-vane roughing pump and an oil diffusion pump with a liquid nitrogen trap. This was about 25 years ago.
Reading here about the troubles of pulling a very good vacuum, I'm now wondering what sorts of painful engineering went into making the machine turn-key and freshman-proof? It's entirely possible that I've mis-remembered the pressure level, but that's the exponent that stuck in my mind for whatever reason.
Mark J. Blair, NF6X <nf6x at nf6x.net>
Web page: http://www.nf6x.net/
GnuPG public key available from my web page.
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