##### 10 August 2020

#### 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 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.

## 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 are initialized from process variables but can be overwritten 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 Measurement Optics' button. The associated quadruple magnets will be made evident in the neighbouring QTableWidget.
- Subsequent measurements with differenct RF Transverse Defector and Profile Monitor combinations require a new setting of the measurement optics.
- With the settings in place, press 'Start' to perform the measurement.
- Once the measurement is complete, information related to the collected (hdf5) data and the generated plots, can be automatically posted to the selected elog book by pressing the ELog icon in the application toolbar.
  The data files are appended with the first 9 digits of the run number, i.e., with one second sampling, as recorded at the start of the measurement.
- Before quitting the application, restore the quadruples to their initial values, 'Restore Initial Values', if warranted.