Cooling of a pure electron plasma by cyclotron radiation

Abstract

It has been suggested that a magnetically confined pure electron plasma might be cooled to the liquid and crystal states. Here, cyclotron radiation is considered as a possible cooling mechanism. The plasma and some cooled resisting medium are assumed to reside inside a conducting cavity. When the cyclotron motion of the electrons resonantly drives a cavity mode which is damped by the cooled medium, energy is transferred from the electrons to the medium. Attention is focused on the case where all of the electrons experience a sharp (i.e., high‐Q) resonance with a single cavity mode. An interesting result is that the rate of energy loss per electron can exceed, by a factor of Q, the radiation rate for an electron executing cyclotron motion in unbounded space. The maximum value of Q is limited by cyclotron damping of the mode on the plasma itself and can be large for a non‐neutral plasma at a density well below the Brillouin limit (i.e., for ω_p<<Ω, where ω_p is the plasma frequency and Ω is the cyclotron frequency).