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

摘要

Radiation 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 w(b)(2) (Omega) over tilde (2), Cherenkov instability in the azimuthal direction with w < (Omega) over tilde + V(z)k(z) leads to the excitation of microwaves. Here, w(b), (Omega) over tilde, w, V-z and k(z) are, respectively, relativistic beam plasma frequency, relativistic electron cyclotron frequency, oscillation angular frequency, axial component of beam velocity and axial wavenumber.