Finite Larmor Radius Modifications to the Magnetoionic Wave Modes and Their Effects on Electron Cyclotron Maser Emission

Auroral kilometric radiation, Jupiter's decametric and Saturn's kilometric radio emissions, solar microwave spike bursts and microwave emissions from some flare stars have all been attributed to the electron cyclotron maser instability. The maser instability is usually assumed to involve the generation of magnetoionic waves. We investigate the modifications to the magneto ionic wave modes due to finite Larmor radius (FLR) corrections arising from a 'warm' background electron plasma with a Maxwellian distribution. We then consider the effects of these modifications on maser emission at frequencies near the fundamental of the electron cyclotron frequency fl e. The FLR effects are found to be small; the maximum temporal growth rate generally differs by ~ 10% from that for emission occurring in the magnetoionic modes. Small shifts occur in the frequencies and propagation angles corresponding to the maximum growth rates.