Mode conversion and electron heating near the upper-hybrid resonance frequency

Abstract
Mode conversion near the upper‐hybrid resonance frequency and electron heating are studied using a one‐dimensional electromagnetic relativistic particle code. It is found that for a sufficiently small pump field E0, E20/4πnTe ≲0.01, electron heating is localized in a region near the electron cyclotron layer where the pump frequency is equal to the local electron gyrofrequency. For stronger pump fields, electron heating takes place more or less uniformly across a region between the upper‐hybrid resonance layer and the cyclotron layer. In addition, a significant fraction of electromagnetic energy associated with the pump is found to be reflected back into the vacuum from a region in the plasma near the upper‐hybrid resonance layer for both strong (E20/4πnTe ≊1) and weak pumps (E20/4πnTe ≪1).