Analysis of radio frequency radiation from a propagating electron beam

Abstract

An experiment was conducted which measured the Radio Frequency (RF) radiation from the PHERMEX accelerator, capable of 30 MeV and 600 A. This was accomplished by placing TEM horn antennae at varying angles from the path of the electron beam. The signals received by the antennae were then recorded by using a Digitizing Camera System (DCS). Measurements were taken of the radiation from propagating and non-propagating beams, beams with energy above and below Cherenkov threshold, and beams with varied currents. The captured RF signals and their corresponding frequency spectra were then analyzed. This analysis showed that the radio frequency radiation from the beams below the cherenkov threshold contained primarily transition radiation; when above, diffracted Cherenkov radiation was observed. Non-propagating beams produced larger-angle radiation and had less definition in their spectrum. All electric fields measured were proportional to the beam current. Lastly, the electron beam pulse width and separation were determined by both the received signals and their spectrum.