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Platform Conditioning
Conditioning the High Field Platform
- Make sure the vacuum space is well pumped
- Lock up the platform and energize the HV power supply
- Check that the Current Potentiometer on the HV Supply is set to
below 1 turn The current setting is 0.83 turns, corresponding to a
current limit of about 0.25 mA (read via needle or via epics)
- Start a strip tool of the HV voltage, current and vacuum (IG3)
- Set the BIAS to 30 kV and condition
Method A
The bias will trip and should stabilize at some low value like 10 kV
but at the current limit ~0.260 mA. Under these conditions there is a
plasma being formed somewhere, and you are conditioning provided the HV
is slowly creeping up, e.g. 1kV/10 minutes. Watch the voltage increase,
and if it does not continue to improve, then you are no longer
conditioning. In this steady-state current limited mode, once you get to
xx kV, the bias will hold 30 kV. The ion gauge is affected by this
plasma.
Method B
Turn the current limiting pot to some low value
- Test the conditioning. Set the set point to some low value (5kV)
and wait a moment for the plasma to dissipate (and the current to drop
to microamps). Slowly increase the voltage to test if it will hold.
- Repeat the procedure w/ the solenoid on and at field
- Repeat the procedure with the solenoid and EL3 on
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