John Wong wrote:

John Wong wrote: Wednesday, June 06, 2012, 16:55 The UO2/C green was prepared on June 04, 2012.  UO2 powder used = 50.26g C-grv used = 10.14g.  Dry UO2/C green mass = 61.71g. The green was rolled and wrapped in a piece of graphite sheet. The target boat was wrapped with 3 Ta-heat shield and installed in the Evap#1.  The chamber is currently being pumped down.    Monday, June 11, 2012, 10:31 Last week during the pump down of the chamber (vacuum got down to low 10e-5 Torr), the cooling was open in preparation of turning on the target heater.  A vacuum excursion was triggered (pressure went up to 300mTorr), and the system was tripped off.  It was suspected that there was some leaks.  A leak test was performed - all the water connecters & joints are fine.  The seal for the chamber lid was found leaky (5e-8 atm cc/sec).  The seal was replaced and the vacuum was improved but no perfect. The chamber has been pumped down over the weekend, pressure currently at 2.3e-6 Torr.  Coincidentally, the TGHT power supply is broken.  The initial action was to turn on the power supply at 0A when the chamber vacuum had gone down to 10-6 Torr.  But the power supply did not regular and shot up to 1000A and caused a vacuum excursion.  Ray Dube will replaced it.

 Tuesday, June 12, 2012, 11:37

Ray Dube repaired the TGHT power supply.  It is now operational.