The first commissioning with beam has been made with the new Transverse Deflecting Cavity on VELA.
The transverse deflecting cavity was designed by ASTeC, STFC Technology Department and The University of Lancaster. Use of the cavity allows the longitudinal properties of the electron beam to be resolved, thus it forms a key component in the suite of diagnostics tools on VELA to enable full 6D phasespace characterisation of the electron bunches produced by the photoinjector electron gun.
Initial measurements taken using the Transverse Deflecting Cavity show the VELA electron bunch length to be of the picosecond to sub-picosecond scale, varying with bunch charge, with results similar to simulations. Knowledge of the bunch length is important for further experiments on VELA, such as electron diffraction. In addition, Understanding how to use this type of device to measure the temporal beam properties will be vital in delivering the high quality electron bunches needed for future FELs such as CLARA (link opens in a new window).