Proposal of a new principle of cyclotron emission from neutralized electron beams

Abstract

AbstractRadiation from a loosely constrained cyclotron motion of mono-energetic electrons on a common large orbit (LO) circle in a uniform axial magnetic field and in a right-hand circularly polarized field of plane electromagnetic waves has been studied numerically by particle simulation. A restoring force caused by neutralizing ions against the displacements of gyrating electrons from the original LO circle is introduced by a phenomenological potential well in the radial direction. It is shown that, in high-density beams such as ωb2 ≫~Ω2, Cherenkov instability in the azimuthal direction with ω <~ω+Vzkz leads to the excitation of microwaves. Here, ωb, ~ω, ω, Vz and kz are, respectively, relativistic beam plasma frequency, relativistic electron cyclotron frequency, oscillation angular frequency, axial component of beam velocity and axial wavenumber.