Generation of coherent THz Cherenkov radiation by electron bunch tilt control

Abstract

We propose a new method that generates coherent Cherenkov radiation by controlling the tilt of the electron bunch. In this scheme, the wavelength band of coherent radiation depends on the transverse size of the electron bunch. This study demonstrates a coherent Cherenkov radiation (CChR) pulse in the THz region corresponding to the beam size. To generate the CChR, we used a 4.8-MeV electron bunch from a photocathode radio-frequency (rf) gun and controlled the angle through an rf transverse deflecting cavity. Our new method increased the pulse intensity by a factor of 7.3 compared to the case without tilting and the THz pulse characteristics well agreed with the prediction.