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Introduction
The need for automating SRF cavity run up
A brief introduction to the software used to run up SRF cavities
| Info |
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Full source code can be found here. It can be run natively on unix systems using the Local PyDM/Simulacrum Setup instructions |
Overview
The need for automation arose from the human error involved in manually implementing a long list of clearly defined steps.
...
- Run an SSA calibration
- Tune a cavity to resonance (a detune of 0Hz)
- Characterize the cavity and calculate the probe Q
- Ramp the RF to the desired amplitude (ADES)
| Info |
|---|
Full source code can be found here. It can be run natively on unix systems using the Local PyDM/Simulacrum Setup instructions |
Pseudocode Walkthrough
SSA Calibration
Using a previously saved drive max found during initial cryomodule commissioning as a starting point (or 1 for the harmonic linearizers), it we recursively runs run an SSA calibration with decreasing drive max until either the calibration succeeds or it hits one of two fault conditions:
- The max forward power is less than 3kW
- The desired drive max is less than 0.5
Auto Tune
- Enable the piezo
- Set the piezo to manual
- Set the piezo DC voltage offset to 0
- Set the piezo bias voltage to 25V
- Set the RF drive level to 15%
- Set the RF mode to chirp
- Find a chirp range that yields a valid detune
- If no valid detune found and chirp range exceeds 500000Hz, throw an error