pyaml.tuning_tools.chromaticity_monitor#

Chromaticity and dispersion measurement tools.

The ChromaticityMonitor acquires and exposes fitted chromaticity or dispersion data from sextupole-based measurements, including read access to the resulting values and their associated units.

Classes

`ChromaticityMonitor`(name, ...[, ...])	Class providing access to a chromaticity monitor of a physical or simulated lattice.
`RChromaDispArray`(parent, name, unit)	Class providing read access to chromaticity or dispersion.

class pyaml.tuning_tools.chromaticity_monitor.ChromaticityMonitor(name, betatron_tune_name, rf_plant_name, bpm_array_name=None, e_delta=0.001, max_e_delta=0.004, fit_order=1, fit_disp_order=1, fit_dispersion=False, n_step=1, sleep_between_step=0, n_avg_meas=1, sleep_between_meas=0)#

Bases: MeasurementTool, DynamicValidation

Class providing access to a chromaticity monitor of a physical or simulated lattice. The monitor provides horizontal and vertical chromaticity measurements.

Parameters:

name (str) – Name of the chromaticity monitor.
betatron_tune_name (str) – Name of the betatron tune monitor used to measure the horizontal and vertical tunes.
rf_plant_name (str) – Name of the RF plant used to vary the RF frequency.
bpm_array_name (str, optional) – Name of the BPM array used for dispersion measurements. Required only when dispersion fitting is enabled.
e_delta (float, optional) – Default relative momentum deviation, delta = dp/p (dimensionless), used during the measurement.
max_e_delta (float, optional) – Maximum permitted relative momentum deviation (dimensionless).
fit_order (int, optional) – Polynomial order used to fit the chromaticity.
fit_disp_order (int, optional) – Polynomial order used to fit the dispersion.
fit_dispersion (bool, optional) – Whether to fit the machine dispersion in addition to the chromaticity.
n_step (int, optional) – Number of RF frequency steps.
sleep_between_step (float, optional) – Delay in seconds after changing the RF frequency.
n_avg_meas (int, optional) – Number of tune (and orbit) measurements to average at each RF frequency.
sleep_between_meas (float, optional) – Delay in seconds between consecutive measurements during averaging.

Attributes

`chromaticity`	Get the chromaticity values.
`dispersion`	Get the dispersion values.
`tune_monitor`	Return the betatron tune monitor used for measurements.
`rf_plant`	Return the RF plant varied during measurements.
`bpms`	Return the optional BPM array used for dispersion measurements.

Methods

`set_mcf()`	Set the momentum-compaction factor for frequency-step measurements.
`measure()`	Main function for chromaticity measurement.
`fit()`	Compute chromaticity (and dispersion) from input data and update

Configuration

- type: pyaml.tuning_tools.chromaticity_monitor
  name: CHROMATICITY_MONITOR
  betatron_tune_name: BETATRON_TUNE
  rf_plant_name: RF
  bpm_array_name: BPM
  fit_dispersion: true
  n_step: 5

fit(deltas, Q, order, orbit=None, fit_disp_order=None, do_plot=False)#

Compute chromaticity (and dispersion) from input data and update latest_measurement.

Parameters:

deltas (array of float) – Relative momentum variation steps, delta = dp/p (dimensionless).
Q (array of [Qx,Qy]) – Measured horizontal and vertical tune (dimensionless).
order (int) – Chromaticity fitting order.
orbit (array of [[x0,y0],[x1,y1],...], optional) – Horizontal and vertical orbit in metres at each energy step, used to fit the dispersion.
fit_disp_order (int, optional) – Dispersion fitting order.
do_plot (bool, optional) – If True, plot the fit.

measure(n_step=None, alphac=None, e_delta=None, max_e_delta=None, n_avg_meas=None, sleep_between_meas=None, sleep_between_step=None, fit_order=None, fit_disp_order=None, fit_dispersion=None, do_plot=None, callback=None)#

Main function for chromaticity measurement.

latest_measurement contains:

chromaticity:np.array # First order chromaticity, Array of [q'x,q'y]
dispersion:np.array # First order dispersion, [[dx'0,..,dx'n],[dy'0,..,dy'n]]
chromaticity_fit:np.array # Array of [[qx,qy],[q'x,q'y],[q''x,q''y],...]
dispersionx_fit:np.array # Array of [[dx0],..,[dxn],[dx'0],..,[dx'n],...]
dispersiony_fit:np.array # Array of [[dy0,..,dyn],[dy'0,..,dy'n],...]

Parameters:

n_step (int) – Default number of RF step during chromaticity measurement [default: from config].
alphac (float | None) – Momentum-compaction factor (dimensionless) [default: from config].
e_delta (float) – Relative momentum variation delta = dp/p (dimensionless): f0 - f0 * e_delta * alphac < f_RF < f0 + f0 * e_delta * alphac [default: from config].
max_e_delta (float) – Maximum permitted relative momentum variation (dimensionless) [default: from config].
n_avg_meas (int) – Number of tune/orbit measurements per RF frequency [default: from config].
sleep_between_meas (float) – Delay in seconds between two tune measurements [default: from config].
sleep_between_step (float) – Delay in seconds after an RF-frequency variation [default: from config].
fit_order (int) – Fitting order [default: from config]
fit_disp_order (int, optional) – Dispersion fitting order [default: from config]
fit_dispersion (bool, optional) – Fit dispersion, [default: from config]
do_plot (bool) – Do you want to plot the fitting results ?

callback (Callable, optional) –

Callback is executed after each measurement or setting. If the callback return false, then the process is aborted. callback_data dict contains:

source:MeasurementTool # Tool that triggered the callback
step:int # The current step
avg_step:int # The current averaging step
rf:float # RF frequency in Hz used for the current step
tune:np.array # Dimensionless measured tune (on Action.MEASURE)
orbit:np_array # Orbit in m, if fit_dispersion is True (on Action.MEASURE)
dtune:np.array # Dimensionless tune variation (on Action.RESTORE)

set_mcf(alphac)#

Set the momentum-compaction factor for frequency-step measurements.

The factor is used to convert an RF-frequency variation into the corresponding relative energy deviation when measuring chromaticity.

Parameters:: alphac (float) – Momentum-compaction factor (dimensionless).

property bpms: BPMArray | None#: Return the optional BPM array used for dispersion measurements.

property chromaticity: ReadFloatArray#

Get the chromaticity values.

Returns:: ReadFloatArray – Chromaticity values [q'x, q'y] (dimensionless).

property dispersion: ReadFloatArray#

Get the dispersion values.

Returns:: ReadFloatArray – Array of dispersion values [[dx, dy], [d'x, d'y], ...], in metres for the first-order values.

property rf_plant: RFPlant#: Return the RF plant varied during measurements.

property tune_monitor: BetatronTuneMonitor#: Return the betatron tune monitor used for measurements.

class pyaml.tuning_tools.chromaticity_monitor.RChromaDispArray(parent, name, unit)#

Bases: ReadFloatArray

Class providing read access to chromaticity or dispersion. Returns arrays of shape (fit_order,2) or None

Parameters:

parent ('ChromaticityMonitor') – Monitor owning the measured values.
name (str) – Attribute of the parent monitor to read, such as chromaticity or dispersion.
unit (str) – Unit reported for the values, such as m.

Methods

`get()`	Return the latest chromaticity or dispersion values.
`unit()`	Return the unit of the reported values.

get()#

Return the latest chromaticity or dispersion values.

unit()#

Return the unit of the reported values.