[Sneap] Turbo pumps and cesium

[Vanvorous, Rick]

Several vendors offer coated turbopump rotors, including Pfeiffer,
Varian, and Leybold.  These are called the corrosive series pumps.  For
larger pumps, above 1,000 l/sec, the rotor surface is an aluminum oxide
conversion process or plasma coated Al2O3.  The rotors on the Pfeiffer
corrosive series 261 and 521 pumps are nickel plated. Both approaches
are one way to deal with the cesium process effluent.  While the moving
part of the pump is coated, the stator and/or housing may not be coated
in all pump types or from all vendors, so it is not a complete solution.


Additionally, you should make sure that the pump is properly purged
during pumping and vented with nitrogen or other inert gas to make sure
that the pumps do not have any un-reacted material left inside the pump
when you stop them. This is suggested even if you resort to trapping
before the turbopump since traps are often inconsistently operated.
This same solution is used for other non-accelerator applications
involving barium, thallium (High temp superconductors), gallium (III/V
semiconductors) and a multitude of other materials in thin film
deposition processes with success.  

Don't use helium for purging unless you can deal with poorer base
pressure.  Helium goes backwards through turbopumps (just like it does
for counter-flow technology leak detectors).

Rick Van Vorous
Senior Sales Engineer
Pfeiffer Vacuum NA - MidAtlantic Region
336-538-1093 Phone 603-578-6550 Fax
Email rick.vanvorous at pfeiffer-vacuum.com  
USA WEBSITE www.pfeiffer-vacuum.com 
 
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-----Original Message-----
From: sneap-bounces at tunl.duke.edu [mailto:sneap-bounces at tunl.duke.edu]
On Behalf Of Karl von Reden
Sent: Tuesday, January 23, 2007 12:21 PM
To: Symposium of Northeastern Accelerator Personnel
Subject: Re: [Sneap] Turbo pumps and cesium

The SNEAP 2005 Meeting was held at Brookhaven National Laboratory.
Please visit the meeting Homepage at:
https://www.bnl.gov/sneap2005/default.asp

The ATF-SNEAP 2006 web site is now available:
http://www.ansto.gov.au/nugeo/conference/private/ATF_SNEAP.htm

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