pyaml.tuning_tools.chromaticity_response_matrix#

Chromaticity response-matrix measurement tools.

The ChromaticityResponseMatrix measures how sextupole-strength changes affect horizontal and vertical chromaticity and stores the fitted slopes as a response matrix.

Classes

ChromaticityResponseMatrix(name, ...[, ...])

Measure the chromaticity response matrix of a lattice.
class pyaml.tuning_tools.chromaticity_response_matrix.ChromaticityResponseMatrix(name, sextu_array_name, chromaticity_name, sextu_delta, n_step=1, sleep_between_step=0, n_avg_meas=1, sleep_between_meas=0)#

Bases: MeasurementTool, DynamicValidation

Measure the chromaticity response matrix of a lattice.

This tool perturbs each sextupole in a sextupole array and measures the resulting chromaticity variation using a chromaticity monitor. The measured slopes are assembled into a response matrix with chromaticity components as the observables and sextupoles as the variables.

Parameters:

  • name (str) – Name of the response matrix measurement tool.

  • sextu_array_name (str) – Name of the sextupole array to excite.

  • chromaticity_name (str) – Name of the chromaticity monitor used to measure the response.

  • sextu_delta (float) – Default sextupole-strength excitation applied during the measurement, in the configured sextupole strength unit (typically m^-2).

  • n_step (int, optional) – Default number of excitation steps used to fit the response.

  • sleep_between_step (float, optional) – Default delay in seconds after changing the sextupole strength.

  • n_avg_meas (int, optional) – Default number of chromaticity measurements to average at each step.

  • sleep_between_meas (float, optional) – Default delay in seconds between averaged measurements.

Methods

measure()

Measure the chromaticity response matrix.

Attributes

sextupoles

Sextupole array used for the measurement.

chromaticity_monitor

Chromaticity monitor used for the measurement.

Configuration

- type: pyaml.tuning_tools.chromaticity_response_matrix
  name: CHROMATICITY_RESPONSE_MATRIX
  sextu_array_name: SEXTUPOLES
  chromaticity_name: CHROMATICITY_MONITOR
  sextu_delta: 1e-6
measure(sextu_delta=None, n_step=None, sleep_between_step=None, n_avg_meas=None, sleep_between_meas=None, callback=None)#

Measure the chromaticity response matrix.

latest_measurement contains:

matrix:list[list[float] # The response matrix
variable_names:list[str] # Variable names
observable_names:list[str] # Observables names

Example

from pyaml.accelerator import Accelerator
from pyaml.common.constants import Action

def callback(action: Action, data:dict):
    print(f"{action}, data:{data}")
    return True

sr = Accelerator.load("tests/config/EBSOrbit.yaml")
acc = sr.design

if acc.crm.measure(callback=callback):
    acc.crm.save("ideal_crm.json")
    acc.crm.save("ideal_crm.yaml", with_type="yaml")
    acc.crm.save("ideal_crm.npz", with_type="npz")
Parameters:

  • sextu_delta (float) – Sextupole-strength change in the configured sextupole unit (typically m^-2).

  • n_step (int, optional) – Number of step for fitting the chomaticity slope [-sextu_delta/n_step..sextu_delta/n_step] Default from config

  • sleep_between_step (float) – Delay in seconds after sextupole excitation. Default: from config.

  • n_avg_meas (int, optional) – Default number of chromaticity measurement per step used for averaging Default from config

  • sleep_between_meas (float) – Delay in seconds between two chromaticity measurements. Default: from config.

  • callback (Callable, optional) –

    Callback executed after each strength setting or measurement. See send_callback(). If the callback return false, then the scan is aborted and strength restored. callback_data dict contains:

    source:MeasurementTool # Tool that triggered the callback
idx:int # The index in the element array being processed
step:int # The current step
avg_step:int # The current averaging step
magnet:str # The magnet being excited
strength:float # Sextupole strength, typically in m^-2
chroma:np.array # Dimensionless measured chromaticity (on Action.MEASURE)
dchroma:np.array # Chromaticity change per sextupole-strength unit (on Action.RESTORE)

Returns:

bool – True when the response matrix is measured successfully; False when the measurement is aborted by the callback.

property chromaticity_monitor: ChromaticityMonitor#

Return the chromaticity monitor used for the measurement.

property sextupoles: MagnetArray#

Return the sextupole array used for the measurement.