Tuesday, May 14, 2024, 10:26 :
Ramping up bias/EE/EL on ITE - will see if the HV cage in the pit can hold 60kV or not.
At around 50kV the bias read current starts to get jumpy. Doesn't look like its an issue for the voltage, but definitely instability increases.
Occasional sparks seem to increase the EL current significantly...
David heard some sparks in the target hall. Looks like from heat shield feed through to the top of the cage. Several sparks heard in the TH also changed the einzel lens draw current significantly. These feethroughs are not far from each other so could be related.
Apparently the sparking also tripped off all the optics and heaters in ITW, by changing the state of the water flow interlock. Interesting and not seen ever before. Will test again with the cage off, rather than risk tripping ITW again.
Tried ramping up the voltage on just the EE. Seems the limit is 7kV - at that level it gets sparky and unstable. Should be investigated (should hold 10kV) but not critical for module function.
Wednesday, May 15, 2024, 10:05 :
HV cover was removed this morning and the MAA was locked out.
Started ramping things up, was very easy until around 58kV. At 59.5kV a spark tripped off the EL. Canbus controller had to be power cycled to fix it. Bias current is much more stable in this configuration.
Ramped up again while listening from the TH to see if it was sparking outside. Went slowly to 60kV (left EL at 29kV) and didn't see any outside sparks in the first 10 mins, couple sparks in vacuum. But after 15 mins a spark seems to have fried the EL canbus card. We were not in the TH so not sure if it was on the outside or not.
After 2 hours a spark tripped off both ITE and ITW. Looks like it makes a water interlock go bad momentarily, but after the trip the interlocks seem fine.
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