##### 2 March 2022

#### Measurement of the electron bunch length using an RF transverse deflector and beam profile monitor.

## About

The application performs a measurement of the electron bunch length using an RF transverse deflector. The profiles of the deflected beam are visualized by profile monitors located downstream. Two RF deflectors have presently been installed at SwissFEL. The first is positioned in the INJECTOR (SINDI01), at z = 84 m, soon after the electron gun, while the second is positioned towards the end of LINAC3 (S30CB10), at z = 386 m. A third deflector further downstream is planned.

## The Panel

How to enable a measurement:

- Select the RF Transverse Deflector and then the Profile Monitor from the drop down menu.
- Modify the configuration parameters (No. Steps, Step Size, etc.) from the default values, if desired.
  The zero-crossing phase and beam energy parameters can likewise be selected by the user.
- Select from the check boxes, the measurements that are to be made.
- Set the measurement optics, which writes to the corresponding quadruple magnets, by pressing the 'Set' button in the 'Optics' group box. The associated quadruple magnets will be made evident in the neighbouring table.
- Subsequent measurements with different RF Transverse Defector and Profile Monitor combinations require a new setting of the measurement optics.
- With the settings in place, press 'Start' in the 'Procedure' box to perform the measurement.
- Once the measurement is complete, the 'Save All' button in the 'Procedure' box will propagate results to epics process variables and hdf5 data files, before sending a summary, with plots, to ELOG.
  Alternatively, data can be saved step-by-step using the approproate icons in the toolbar.
  The HSF and image file names are appended with the date the analysis procedure began.
- Before undertaking a new measurement, or before quitting the application, restore the quadruples to their initial values, using the 'Restore' button in the 'Optics' group box.