David raised the bias to 49.5kV. Module is still sparking mainly on top. Humidity is super high.
Wednesday, July 10, 2019, 09:50 : sitting at 49.7kV for a coupe mins, big spark in vacuum took everything down.
Wednesday, July 10, 2019, 10:16 : Bias at 50kV drawing 0.1mA but looking pretty jumpy. Left it here for ~5 mins then had to turn down bias for TH work.
Wednesday, July 10, 2019, 13:33 : Back at 50kV on bias with no problems.
Wednesday, July 10, 2019, 13:46 : 10 mins at 50kV, will try to go a bit higher
Wednesday, July 10, 2019, 14:06 : Everything sparked off while sitting at 50.6kV. This seems a bit futile....
Wednesday, July 10, 2019, 14:15 : Back at 50.1kV with no problems
Wednesday, July 10, 2019, 14:33 : Up to 51kV
Wednesday, July 10, 2019, 15:20 : Difficult to go above 51.4. Turning up EZL since there were a couple sparks to it. -> Putting this up causes significant sparks between HV bias and EZL in vacuum at 5kV on the EZL, 51.1kV on bias. Leaving EZL @ 5kV
Wednesday, July 10, 2019, 16:04 : Around 52.2 sparking on the top of the module
Wednesday, July 10, 2019, 16:36 : 53kV
Wednesday, July 10, 2019, 17:16 : up to 54kV without much trouble
Wednesday, July 10, 2019, 17:53 : Sitting at 55kV for about 4mins when a spark tripped off everything. Will try to bring it back to sit stable at 55kV tomorrow
Thursday, July 11, 2019, 10:28 : TM4 up to 54.9kV without too many problems, EZL at 25kV. Will sit here for a little while
Thursday, July 11, 2019, 10:48 : 20mins at 54.9kV, going to 55kV
Thursday, July 11, 2019, 11:14 : 25 mins at 55kV and everything sparked off
Thursday, July 11, 2019, 11:26 : Back up to BIAS / EZL = 54.8kV / 26kV. Checked that the TGHT and TBHT power supplies have not been killed by sparks, everything looks fine.
Thursday, July 11, 2019, 12:56 : Sat at 49.6kV for 1.5hrs with one spark.
Thursday, July 11, 2019, 14:02 : Been sitting at 55kV for 2 hrs now with one spark.
Friday, July 12, 2019, 08:09 : Back up to 52kV easily, then had to reduce step size to 100V to keep going
Friday, July 12, 2019, 08:47 : 56kV
everything sparked off at 56.5 or so
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TM4 has developed 4 leaks so far:
- Line B - seems to be solved with an indium gasket (some testing already done)
- Line D - seems to be solved with an indium gasket (some testing already done)
- EE - indium gasket installed, preliminary tests are good
- Window cooling line - David found with 70 psi helium, leak detector response went from 3E-7 atm.cc/sec to 4E-4torr atm.cc/sec in 1 min and stayed there. When water was put through the circuit, there was an initial vacuum increase to about 1E-6, then a couple hours later it began to fall and has been falling for ~14hrs, now in the 7E-7 range for IG1.
Testing indium seals on lines B, D, EE. No repair has been done for window line. Ramping heaters to TGHT=450A, TBHT=200A. Everything behaving normally.
Wednesday, ramped up BIAS, EZL and EE to 36kV, 17kV, 1.5kV. Sparking at about 1 spark per 20 - 30 mins. Bias current somewhere between 66uA and 78uA, varying with the chiller ON/OFF.
Thursday morning around 2am everything tripped off. No spark visible on strip tool, seems this is from an increase in the window water leak. Vacuum recovered on its own and heaters were ramped back up. |