Pirani, LaB6

Pirani gauge on RP-1 replaced with spare. This appears to have fixed the vacuum problem. Also, RP-1 and RP-2 cables were reversed. LaB6 tip reinstalled. Seems OK.

TEM status

During use last week, the TEM began to close the high vacuum valves and restart the evacuation cycle. Sometimes this was when inserting/removing the holder; other times it seemed unrelated to the holder. The symptoms were the same as those we had previously attributed to the turbo-pump problem. The problem grew worse, until eventually the valves would close every time a holder was inserted or removed.

John Martin (Hitachi) worked on cleaning the holders and the ball valve for the sample load lock, replacing several o-rings. He also drilled holes in the electronics cabinet to improve cooling of the TMP controller. He adjusted the Pirani gauge thresholds, which may have been indicating poor backing pressure, causing the vacuum failure status. At the moment, the problem seems to be remedied.