The Ohio State University College of Mathematical & Physical Sciences Department of Astronomy

March 2001: Vacuum system testing

Initial vacuum pumping tests with the bell jar lid and dummy mirror cell were carried out by Bruce Atwood and Dan Pappalardo during the first weeks of March. The first pump tests were very encouraging and met all of our goals. There were the inevitable leaks, but the effective size is only ~70 microns diameter (calibrated against a reference 100 micron pinhole). The system was back-filled with 200 cu-ft of helium and sniffed with hand-held leak testers. Two leaks were found right away: 1 associated with a hermetic connector that was not properly seated. In all we need to test about 250 meters of welds during later tests.

Pictures of the mirror cell and bell jar lid were taken during the testing by Dan Pappalardo & Bruce Atwood. Click on the thumbnail below to see the full-resolution image (each approx 300Kb). These are not yet annotated.

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