Re: big Diffusion pumps

To: neon-l@netcom.com
Subject: Re: big Diffusion pumps
From: marcus@ttphysik.uni-duisburg.de
Date: Sun, 7 Apr 1996 22:39:59 +0100 (MESZ)
In-Reply-To: <960407003808_265817811@mail04> from "Neonmc@aol.com" at Apr 7, 96 00:38:09 am
Reply-To: neon-l@netcom.com
Sender: owner-neon-l@netcom.com

> 
> Marcus, 
> You have a four stage metal pump?  Please elaborate.
> Morgan

Dear Morgan,
yes, you may call it 4 stage, from outside this looks as a single stage, 
but when disassembling, you will see 4 venturi nozzles in a coaxial assembly.
This is today's standard in high vaccum technique. 
You need only one cylindrical outer wall, water cooled, where the vapour 
condenses, but there are 4 steam curtains, one above the other.
Without a nitrogen cold trap you will get absolute vacuum in the 10e-7 range, 
with LN2 baffle  10e-10, depending on the oil you're using. 
absolute vacuum also depends on the vapour spped, i.e. dimensions of the 
venturi and CLEANING of the surface. Polish it as a mirror!

I'm sorry not to be able to use this pump, because the heater power would
swallow more than additional 500W, and i'm not allowed to have a water 
supply in the garage. Planned to have a tank and air back cooling 
circulation cooling system. But 500W Diffusion, 200W Motor roughing punp 
PLUS Bombarder, all on a single 16Amp 220Volt outlet is too much to the fuse.
So I keep it until I have time to add it to the system in that way, 
that it's heat capacity will support pumping during time when the Bomber is on.

Hope this description helps. 
In our lab we pump to 1e-13 mbar, up to 1e-10 with Diffusion pumps. 

Marcus Thielen
student of physics at Duisburg University.
email: marcus@ttphysik.uni-duisburg.de

References:

Re: big pumps

From: Neonmc@aol.com