Electron Beam Instability in Left-Handed Media

TL;DR

This paper predicts a unique instability caused by backward Cherenkov radiation when two electron beams pass through left-handed media, leading to self-modulation and chaotic electromagnetic radiation.

Contribution

It introduces the first theoretical prediction of electron beam instability specific to left-handed media due to backward Cherenkov radiation.

Findings

Instability occurs only in left-handed media.

Radiation spectrum shows well-separated lines indicating chaos.

Radiation intensity and spectrum are controllable via beam current and spacing.

Abstract

We predict that two electron beams can develop an instability when passing through a slab of left-handed media (LHM). This instability, which is inherent only for LHM, originates from the backward Cherenkov radiation and results in a self-modulation of the beams and radiation of electromagnetic waves. These waves leave the sample via the rear surface of the slab (the beam injection plane) and form two shifted bright circles centered at the beams. A simulated spectrum of radiation has well-separated lines on top of a broad continuous spectrum, which indicates dynamical chaos in the system. The radiation intensity and its spectrum can be controlled either by the beams' current or by the distance between the two beams.