Detune computation for Resonance Control
Detune Computation block does not seem to provide correct detuning frequency error for resonance control.
Need to understand the differences in detuning calibration data processing between the Berkeley implementation
and the Fermilab LLRF data acquisition and scaling.
#1 Updated by Philip Varghese 2 months ago
- File HWR_Cavity7_Det_NewCal.dat HWR_Cavity7_Det_NewCal.dat added
- File HWR_Cavity6_Det_NewCal.dat HWR_Cavity6_Det_NewCal.dat added
- File HWR_Cavity5_Det_NewCal.dat HWR_Cavity5_Det_NewCal.dat added
- File HWR_Cavity4_Det_NewCal.dat HWR_Cavity4_Det_NewCal.dat added
- File Cavity8_newCal_output.pdf Cavity8_newCal_output.pdf added
- File Cavity7_newCal_output.pdf Cavity7_newCal_output.pdf added
- File Cavity6_newCal_output.pdf Cavity6_newCal_output.pdf added
- File Cavity5_newCal_output.pdf Cavity5_newCal_output.pdf added
- File Cavity4_newCal_output.pdf Cavity4_newCal_output.pdf added
- File Detune_Cal_Scaling_v2.pdf Detune_Cal_Scaling_v2.pdf added
Following discussions with Larry and Sergio, the detune calibration procedure was modified as follows.
1) The input data to the python scripts generating the coefficients was modified to unscale the data as
shown in the Detune Scaling document attached.
2) The pulse mode data taken for each cavity was done with larger gradients approaching 1/2 FS as opposed to the
~1/8 FS values used before.
3) Coefficients 0 and 1 were inverted in sign because this effectively inverts the sign of the detune output from the
detune block. When the cavity resonance is greater than the reference frequency, the detune frequency is negative by
definition of the underlying equations. The control output needs to be increased to increase the cavity pressure which
reduces the resonant frequency. The correct way to deal with this situation is to invert the detune output and not just the
3)Cavities 4,5,6,7 and 8 were recalibrated and the cavities run in GDR mode with the new coefficients. The performance was
much improved compared to the results obtained earlier this week with coefficients obtained by trial and error. Cavity
4 could not be run long enough due to RFPI problems and will be retested today.
4) At this point we have a functional detune computation block and the confusion regarding the data input to the firmware
block and the coefficient calculation scripts is understood and accounted for in the data processing.
5)The calibration data files, the python script outputs and the modified scripts are attached.
#3 Updated by Philip Varghese 2 months ago
- File HWR_Cavity8_Aug26_20_Data.dat HWR_Cavity8_Aug26_20_Data.dat added
- File HWR_Cavity7_Aug26_20_Data.dat HWR_Cavity7_Aug26_20_Data.dat added
- File HWR_Cavity6_Aug26_20_Data.dat HWR_Cavity6_Aug26_20_Data.dat added
- File HWR_Cavity5_Aug26_20_Data.dat HWR_Cavity5_Aug26_20_Data.dat added
Cavity, Forward, Reflected and Freq Error saved waveforms for cavity 5,6,7 and 8 in GDR mode at the operational gradient are