Emission of coherent microwave radiation from a relativistic electron beam propagating in a spatially modulated field

Abstract

Intense electromagnetic radiation has been observed from the interaction of an intense relativistic electron beam and a spatially modulated magnetic field. An efficiency of conversion of electron kinetic energy into microwave radiation of the order of 1% has been achieved, with total rf power radiated greater than 30 MW. A parametric study has shown that the device has not reached saturation over the range of parameters tested. The experimental results show that the new device differs from conventional generators in several respects. For example, the frequency and the bandwidth of the rf radiation can be tuned over a wide range and the power at the harmonics of the fundamental frequency ${\text{(∼\hspace{0.17em}10}}^{10}\hspace{0.17em}\mathrm{Hz})$ is the same order of magnitude as the power in the fundamental. Infrared radiation has also been observed; more than 1 MW has been found even for wavelengths under 10 $\mu \mathrm{m}$ .