[Sneap] RF Puzzle

[jim]

  Hi 
 Is there not a bleed resistor on the circuit that could have a bad ground connection when machine is under pressure, especially if SF6 is used. I have found this before to be a source of problems. a A similar problem arises with the plugs used to connect the plate and grid currents for testing.
 Cheers Jim
  ----- Original Message ----- 
  From: Gerhard Randers-Pehrson 
  To: 'Symposium of Northeastern Accelerator Personnel' 
  Sent: Tuesday, July 03, 2007 1:25 PM
  Subject: [Sneap] RF Puzzle


  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/.




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  Hello all

   

  Our RF ion source is acting strangely:

   

  When probe voltage is applied, we get no probe current, and there is no change in beam current which is very small.

   

  With the machine open, the voltage is present on the probe cap and the current meter indication is consistent with the meter resistance.

   

  It is as though there is a resistive layer inside the cap.

   

  The bottle had been in use only 6 days before this happened and worked ok until then.

   

  Any clues or cures?

   

  Gerhard



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