Chromaticity measurement alexandre moutardier

[Amoutardier]

Module to measure chromaticity using frequency shift method.

[JeanLucPons]

Thanks @Amoutardier for this nice job !
Few remarks:

• All pyAML devices should be attached in post_init() to allow configuration error detection at early stage. post_init() is call after all underlying pyaml device are created.
  Move to code below to post_init().

tune = self._peer.get_betatron_tune_monitor(self._cfg.betatron_tune)
rf = self._peer.get_rf_plant(self._cfg.RFfreq)

• Add the way to select the order and fit a polynomial rather than method=linear | quad, it you select 1 then chromaticity_monitor.chromaticity.get() should return $[[q'_x,q'_y]]$, if you select 2 $[[q'_x,q'_y] , [q''_x,q''_y]]$, etc...

• Add the way to retreive the tune scan data to allow the plot to de done by the user

[JeanLucPons]

2 additional remarks:

• you can simplify the code by giving up the abstract implementations and respective attachments in control system and simulator. This will just prevent to call get_chrom() from AT but the scan you do should also work on the model

• Concerning the moment compaction factor, I would prefer to not have a default value, if None, the measurement should raise an Exception. We may add a default to at.lattice.get_mcf() if a model is defined.

[JeanLucPons]

@Amoutardier
I did the change, let me know if it is ok for you.

import time
from pyaml.accelerator import Accelerator
import numpy as np

sr = Accelerator.load("tests/config/EBS_chromaticity.yaml")
sr.design.get_lattice().disable_6d()
alphac = sr.design.get_lattice().get_mcf()
print(alphac)
chromaticity_monitor = sr.live.get_chromaticity_monitor("KSI")
chromaticity_monitor.chromaticity_measurement(do_plot=True, fit_order=1, alphac=alphac, N_tune_meas=1, N_step=5, Sleep_between_meas=0, Sleep_between_RFvar=4, E_delta=1e-3, Max_E_delta=1e-3)
ksi = np.abs(chromaticity_monitor.chromaticity.get())
print(ksi)

fit_order=2

fit_order=1

[gubaidulinvadim]

I think it is good. We probably need to place this chromaticity measurement in a different place. It is different from TuneMonitor because for tune there's a direct connection to a device that gives Q_x and Q_y (we can imagine the same for Q_s too). In this case, it is a real measurement that is not done in the background transparently. We do not have any "measurement" directory and, for me, this is a measurement, not a "tuning tool".

[JeanLucPons]

I agree.
And this kind of pyaml device should access only pyaml "low level" device. I mean by "low level" devices , devices that have direct connection to CS.