Deformation of electron holes in phase space as prerequisite for narrow band maser emission: A qualitative discussion

TL;DR

This paper discusses how deformed electron holes in phase space, caused by interactions with specific electron distributions, are essential for generating narrow band emissions in electron cyclotron maser radiation, based on qualitative analysis.

Contribution

It introduces a qualitative model explaining how electron hole deformation leads to narrow band maser emission in space plasmas.

Findings

Deformed electron holes create steep velocity gradients leading to narrow band emission.

Interaction with ring or horseshoe distributions causes phase space deformation.

Emission and absorption bands shift in frequency due to electron hole displacement.

Abstract

A qualitative discussion is given of the role electron holes play in generating fine structure on the electron cyclotron maser radiation. It is argued that electron holes become deformed in phase space when interacting with an incomplete ring or horseshoe distribution which occurs in the presence of strong field aligned electric fields in the upward current region and in the presence of a loss cone. This interaction is based on momentum balance considerations. Deformed narrow electron holes cause steep velocity space gradients on the ring distribution that lead to intense but narrow band emission from their high speed sides and absorption at slightly higher frequency from their low speed sides. The twins of banded emission and absorption move in frequency space due to the average real space displacement of the deformed electron hole.