Microwave radiation from a low-energy rotating electron beam in an azimuthally periodic magnetic wiggler field

The generation of microwave radiation by the interaction of a low-energy rotating electron beam (25 kV, 0.5 A, 5 μs) with an azimuthally periodic magnetic wiggler field has been studied experimentally. Narrow-band radiation has been observed at a frequency of 10.15 GHz at power levels of about 100 W, correspoinding to an electronic efficiency of about 1 percent. Results are in reasonable agreement with theoretical expectations when the electron cyclotron frequency is adjusted to account for a precession in the electron orbits caused by the wiggler field.