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User name stevensm
Log entry time 14:27:26 on August25,2005
Entry number 153279
This entry is a followup to: 152847
keyword=target chamber vacuum gauge fluctuation
We were troubleshooting the target chamber cold cathode gauge readback fluctuation. The gauge was stable at the bottom of the 7 range when we entered the hall. Flexing the wiring on the cold cathode transducer head and at the back of the gauge unit did not cause any fluctuations in the readout. We put the residual gas analyzer (rga) onto the target chamber and saw that helium was down in the 9 - 10 range. More than 90 per cent of the residual gas is air and water (by the rga), and there is visible water frost on the target assembly. It is obvious that there is either and atmosphere or a water (sweeper magnet) leak, or perhaps both. We sprayed the outside of the target chamber with helium, but didn't see any change in the helium partial pressure on the rga. We removed the rga from the target chamber and exited the hall.