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| Vacuum testing began this week. The side flanges with the piston connections and thermocouple feedthroughs were attached. In addition, the bottom flange was attached, complete with feedthroughs for the electrical outputs (motor, etc), special high voltage connections, liquid nitrogen, and spare vacuum connection. All other connections were sealed with blank flanges while the chamber was pumped down to a pressure of 8e-3 mbar (after 40.minutes of pumping). | |
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| Leak testing identified a couple of leaks. One very large leak was due to an incorrectly sized O-ring on one of the feedthrough. This was very quickly and easily replaced. The second leak was a minor leak along the welding of the vacuum chamber. An overnight test (approximately 15 hours) was performed and showed an increase in pressure from 9.4e-3 to 7.8e-1 mbar. While the vacuum pumps might easily maintain the inner vacuum pressure necessary for the experiment in this case, the chamber was re-welded to be sure that ice will not build up on the experiment during the flight (potentially slowing, or even stopping, movement). Vacuum testing up to this point indicates that the chamber is functioning well and the vacuum seal is in excellent shape. | |
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