Evaluation of electron bunch shapes using the spectra of the coherent radiation

The bunch shape of single-bunch electron beams, generated with a 38 MeV L-band linear accelerator, was evaluated using the longitudinal bunch form factor at the Institute of Scientific and Industrial Research at Osaka University. The single-bunch beams are being used in experiments for generating self-amplified spontaneous emission and coherent radiation. In the present experiments, the energy of the electron beam was 27 MeV, the energy spread 1.1% FWHM, and the electron charge in a bunch 13.5 nC. The form factor was obtained from the spectrum of the coherent transition radiation measured with a Martin–Pupplet interferometer. A streak measurement was also performed in the same configurations and the results were compared to those for the measurements of the coherent radiation. By using these two methods, the performance of a chicane-type bunch compressor was investigated.