poor vacuum

Microscope running OK, but penning gauge pressure is poor. Noticed significant oil leak from RP-3. TEM off to evaluate situation. May need to remain off until Wed. Jan. 6 after return from travel.

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.

turbo-pump status

Provac Sales, Inc. found the problem we had anticipated with the turbo-pump controller. One of the internal power supplies was intermittently failing. The controller is repaired, but they are only now beginning to rebuild the pump itself. The have agreed to send us a loaner pump that should be shipped today. So it is possible we could install that on Monday and begin to use the TEM on Tuesday.

The turbo pump has stopped working and was sent to Provac for repairs on 9/3/2009, along with the turbo pump controller. The pump and controller are made by Seiko. The repair is expected to take 2-3 weeks, so the TEM will be down until at least 9/17/2009.

The problem started after a planned power outage in late July. The TEM was turned off the night before, but when we tried to restart the next day, the pump made a horrible clanging noise. Eventually, we got it working, by unplugging the pump from the controller and restarting. Then, an unplanned power outage occurred a couple of weeks later, and the pump clanged for many hours during the night. At this point we started having loss of vacuum issues. So the problem may have started with the controller, causing damage to the pump.