Numerical investigation of auroral cyclotron maser processes

Journal Article · Sat May 15 04:00:00 EDT 2010 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3371937· OSTI ID:21371305

Speirs, D C; Ronald, K; McConville, S L; Gillespie, K M; Phelps, A D. R.; Cross, A W; Robertson, C W; Whyte, C G; He, W ^[1]; Bingham, R ^[1]; Vorgul, I; Cairns, R A ^[2]; Kellett, B J ^[3]

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1. Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG, Scotland (United Kingdom)
2. School of Mathematics and Statistics, University of St. Andrews, St. Andrews KY16 9SS, Scotland (United Kingdom)
3. Rutherford Appleton Laboratory, Space Physics Division, STFC, Didcot OX11 0QX (United Kingdom)

When a mainly rectilinear electron beam is subject to significant magnetic compression, conservation of magnetic moment results in the formation of a horseshoe shaped velocity distribution. It has been shown that such a distribution is unstable to cyclotron emission and may be responsible for the generation of auroral kilometric radiation--an intense rf emission sourced at high altitudes in the terrestrial auroral magnetosphere. Particle-in-cell code simulations have been undertaken to investigate the dynamics of the cyclotron emission process in the absence of cavity boundaries with particular consideration of the spatial growth rate, spectral output and rf conversion efficiency. Computations reveal that a well-defined cyclotron emission process occurs albeit with a low spatial growth rate compared with waveguide bounded simulations. The rf output is near perpendicular to the electron beam with a slight backward-wave character reflected in the spectral output with a well defined peak at 2.68 GHz, just below the relativistic electron cyclotron frequency. The corresponding rf conversion efficiency of 1.1% is comparable to waveguide bounded simulations and consistent with the predictions of kinetic theory that suggest efficient, spectrally well defined emission can be obtained from an electron horseshoe distribution in the absence of radiation boundaries.

• OSTI ID: 21371305
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 17; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
AMPLIFIERS
AURORAE
BEAM-PLASMA SYSTEMS
BEAMS
COMPRESSION
DISTRIBUTION
ELECTRON BEAMS
ELECTRONIC EQUIPMENT
EQUIPMENT
LEPTON BEAMS
MAGNETIC COMPRESSION
MASERS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
PARTICLE BEAMS
PLASMA SIMULATION
SIMULATION
VELOCITY