Radiation of the electron bunch moving in non-regular fields

TL;DR

This paper investigates the spontaneous radiation emitted by an electron bunch moving over a rough metallic surface with randomly distributed asperities, revealing how surface roughness affects radiation spectra and proposing a new surface analysis method.

Contribution

It introduces a model for electron bunch radiation over irregular surfaces using gamma-distributed asperity spacings and derives radiation characteristics, including a novel non-destructive surface roughness measurement technique.

Findings

Angular distributions of radiated photons are similar for bunch and single electron.

Frequency distribution of the bunch significantly changes at high frequencies.

Derived gain expression for stimulated radiation based on the frequency distribution.

Abstract

The problem of spontaneous radiation of the electron bunch grazing into a charged metallic surface with randomly distributed needle shaped asperities is considered. Distances between two neighboring asperities have been described by gamma distribution. Being repealed by highly charged asperities the electrons of the bunch move along non-regular periodical trajectories in the planes parallel to the metallic surface. The spatial periods of the trajectories are random quantities which are described by the same gamma distribution. The radiation characteristics of the bunch have been obtained. It is shown that the angular distributions of the number of photons radiated from the bunch and from a single electron are the same but the frequency distribution of the bunch is being drastically changed at the hard frequency region. It is proposed to develop a new non-destructive method for investigation of the metal surface roughness. The frequency distribution of the number of photons radiated under the zero angle has been obtained. That allows to find the gain expression of the stimulated radiation.