[Sbs_gems] [New Logentry] Brief Test of J0 HV at lower HV Values

[ewertz at jlab.org]

Logentry Text:
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Earlier this morning there was an opportunity to briefly turn on the HV for J0, the beam was down for a short time. So I ramped each module on INFN J0 to 100 Vs and 300 Vs. At 100 V we expect the HV current readback to be about 2.5 uAmp. At 300 V we expect the HV current readback to be about 7.6 uAmps. Any major deviations from this is an indication of a potential problem. I have attached the relevant plots or HV GUIs during that process. We see the following information.

INFN J0 Bot:
Voltage Setpoint: 100 V, Voltage Readback: 99.1 V, Current Readback: 2.03 uAmps
Voltage Setpoint: 300 V, Voltage Readback: 299.2 V, Current Readback: 6.86 uAmps

INFN J0 Mid:
Voltage Setpoint: 100 V, Voltage Readback: 99.3 V, Current Readback: 2.68 uAmps
Voltage Setpoint: 300 V, Voltage Readback: 299.5 V, Current Readback: 8.085 uAmps

INFN J0 Top:
Voltage Setpoint: 100 V, Voltage Readback: 99.7 V, Current Readback: 2.545 uAmps
Voltage Setpoint: 300 V, Voltage Readback: 299.9 V, Current Readback: 7.595 uAmps

The only module that is still operating normally is J0 Top. The current readback is consistent with expectation. J0 Mid is drawing more current than the expect values, which is consistent with the development of new shorted sectors. J0 Bot is actually drawing less current than the expected values and I am not actually sure what that indicates. I will consult with other GEM folks about this matter. Regardless this is good information to know moving forward.

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