Spontaneous emission measurements from a low voltage pre-bunched electron beam

Measurements have been carried out on the spontaneous microwave (8.25 GHz) emission which results when a low-voltage (55.5 kV), pre-bunched electron beam is passed through a waveguide in a wiggler magnetic field. The variation of the spontaneous emission output power level with the average electron beam energy and current are reported and compared with a recently presented theory. The effect of the degree of bunching of the electron beam on the spontaneous output has also been observed and is again compared with theory.