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. |