TM2 is in the TCS without containment box for HV testing following the installation of the IGLIS wiring.
Not great results so far - sat at 42.5kV for nearly 2 hours, current around 200uA and occasional sparks. I did not have time to go higher, will do this tomorrow. The sparks could be conditioning but it looks a bit suspicious to me. We will see if the ramp up tomorrow is very easy and how high we can go. I have data from HV testing of TM2 in December for comparison.
The EZL was reacting to all sparks, so I went into the target hall to see if it was sparking on the module top, but there was no sparking there.
Possible mitigations:
- Re-do the connections on top of the service cap to remove the extra length on the wires inside the service cap and inspect the routing carefully to make sure nothing is in the wron place.
- Inspect the wiring in the source tray to see if there is evidence of sparking in a certain area.
Second round of testing Tuesday April 5 2022:
Much better results, seems most of the sparking was conditioning. Went right up to 42.5kV with no issues. Spent quite a while getting up to 50kV, and didn't leave it there for more than a couple mins. May be running into the limitations of the HV cage at this point. Bias current was much lower, something like 140uA at 45kV.
Third round of testing Wednesday April 6 2022:
Ramped easily back to 45kV, a little more sparking above that. Sat at 47kV for ~30mins with no sparks. Won't try to go higher in case of issues with the cage. Will try to condition up to 50kV in the station. Other than the possible low megger value between B and C, all looks good. |