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Introduction

The need for automating SRF cavity run up arose from the human error involved in manually implementing a long list of clearly defined steps. 

The basic procedure is:

  1. Run an SSA calibration
  2. Tune a cavity to resonance (a detune of 0Hz)
  3. Characterize the cavity and calculate the probe Q
  4. Ramp the RF to the desired amplitude (ADES)


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), we recursively 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

  1. Enable the piezo
  2. Set the piezo to manual
  3. Set the piezo DC voltage offset to 0
  4. Set the piezo bias voltage to 25V
  5. Set the RF drive level to 15%
  6. Set the RF mode to chirp
  7. Find a chirp range that yields a valid detune
    1. If no valid detune found and chirp range exceeds 500000Hz, throw an error




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