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 <n...@nf6x.net> Web page: http://www.nf6x.net/ GnuPG public key available from my web page. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.