[Sneap] alternatives to SF6

[Chris Westerfeldt]

Larry, As Nathan has said, adding a small percentage of SF6 to the normal
80/20 Nitrogen/CO2 blend that HVEC machines use, greatly improves
performance.  If I am not mistaken, Notre Dame doesn't even use CO2 any
more, just Nitrogen and SF6 to achieve 10+ MV on their FN.  The major
obstacle that I see in your case is that you tank is probably not rated for
the ~200 psi that we operate these blends at.  I am not sure if you will
be able to operate Nitrogen/SF6 at only 80 psi and get stable performance.
Has anyone with a Pelletron tried this?  Greg, has NEC ever done any tests
along these lines??
    In my files I find a paper by Phil Ashbaugh et al from Chalk River in
1965 where they compared pure SF6 to the Nitrogen/CO2 blend and found that
the relative dielectric strength of SF6 to Nitrogen/CO2 in an EN was roughly
3:1 with the SF6 at 60 psi and the blend at 250 psi.
    I also find a letter from a technical specialist at Allied Chemical
dated 1979 to someone discussing using a blend of Nitrogen and SF6 in some
electrical bus system.  I will attach that letter and a data table attached
to it which gives breakdown voltages for various mixtures of these two gases
at different pressures.  Hopefully this will be helpful.
- Chris
-- 

Chris R. Westerfeldt
Research Scientist / T.U.N.L. Radiation Safety Manager
Duke University Physics Department &
Triangle Universities Nuclear Laboratory
Science Drive, Box 90308
Durham, NC  27708-0308
Tel: (919) 660-2600
Fax: (919) 660-2634
Email: Cwest at Tunl.Duke.Edu


> From: Larry Ahle <ahle1 at llnl.gov>
> Reply-To: Symposium of Northeastern Accelerator Personnel
> <sneap at tunl.duke.edu>
> Date: Tue, 04 Sep 2007 19:17:27 -0400
> To: <sneap at tunl.duke.edu>
> Subject: [Sneap] alternatives to SF6
> 
> The ATF-SNEAP 2006 meeting was held in Australia and information is available
> at:
> http://www.ansto.gov.au/nugeo/conference/private/ATF_SNEAP.htm
> 
> ++++++++++++++++++++++++++++++++++++
> 
> The SNEAP 2007 meeting will be hosted by Brigham Young University in Salt Lake
> City Utah. The meeting web site is located at:
> http://webpub.byu.net/wsd/.
> The 41st SNEAP Conference
> Brigham Young University
> October 7 - 11, 2007
> 
> Please note:
> DUE TO THE ORIGINAL ANNOUNCEMENT BEING LOST IN CYBER-SP[ACE, THE
> SUBMISSION DATE HAS BEEN EXTENDED TO September 15th
>  
> Call for Papers: 
> 
> Brigham Young University in sponsoring the 41st Conference of the
> Symposium of North Eastern Accelerator Personnel (SNEAP) on October 7-
> 11, 2007. The conference will be held at the Embassy Suites Hotel in
> Salt Lake City, Utah.
> 
> The SNEAP Conference is directed toward scientists and technical staff
> who are involved in developing, upgrading, and operating electrostatic
> accelerators. Further information about the conference is available at
> the conference website:
>  
> 
> http://webpub.byu.net/wsd.
> 
> 
> We invite presentations on topics relating to accelerator design,
> operation, and improvement, and to unresolved problems with accelerator
> systems. Please send a title and abstract of your proposed presentations
> to sneap at byu.edu by September 15.
>  
> Contacts:
> Scott Daniel       wsd at byu.edu
> Lawrence Rees      sneap at byu.edu
> We are retrofitting an existing pelletron that has been moth balled
> for many years.  Unfortunately, the gas storage system developed a
> leak during that time and so we have no SF6.  We are interested in
> any info about possible gas mixtures that are more economical than
> SF6 but have comparable insulating properties.  Thanks.
> 
> Larry
> 
> ===================================
> Larry Ahle
> Lawrence Livermore National Laboratory
> L-414
> PO Box 808
> Livermore, CA 94551
> phone: (925)422-1621    FAX: (925)422-5940
> email: ahle1 at llnl.gov
> ===================================
> _______________________________________________
> Sneap mailing list
> Sneap at daytona.tunl.duke.edu
> http://daytona.tunl.duke.edu/mailman/listinfo/sneap

-------------- next part --------------
A non-text attachment was scrubbed...
Name: CCE00000.pdf
Type: application/pdf
Size: 118777 bytes
Desc: not available
Url : http://daytona.tunl.duke.edu/pipermail/sneap/attachments/20070906/5ef81a20/attachment-0001.pdf