Numerical simulation of unconstrained cyclotron resonant maser emission

D. C. Speirs, K. M. Gillespie, K. Ronald, S. L. McConville, A. D R Phelps, A. W. Cross, R. Bingham, B. J. Kellett, R. A. Cairns, I. Vorgul

Research output: Contribution to journalArticle

Abstract

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 (AKR) - an intense rf emission sourced at high altitudes in the terrestrial auroral magnetosphere. PiC
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 to 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 2.68GHz, 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 radiation emission can be obtained from an electron horseshoe distribution in the absence of radiation boundaries.

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masers
cyclotrons
output
radiation
simulation
electron beams
waveguides
backward waves
cyclotron frequency
high altitude
kinetic theory
magnetospheres
conservation
electrons
velocity distribution
magnetic moments
cavities
predictions

Keywords

  • electron beam
  • electron cyclotron maser
  • auroral cyclotron maser
  • Auroral kilometric radiation
  • cyclotron maser radiation
  • PiC code simulation

Cite this

@article{d5ab97d2941f4e3b9c56597aa967f4f7,
title = "Numerical simulation of unconstrained cyclotron resonant maser emission",
abstract = "When a mainly rectilinear electron beam is subject to significant magneticcompression, 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 (AKR) - an intense rf emission sourced at high altitudes in the terrestrial auroral magnetosphere. PiCcode 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 to 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 2.68GHz, 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 radiation emission can be obtained from an electron horseshoe distribution in the absence of radiation boundaries.",
keywords = "electron beam, electron cyclotron maser, auroral cyclotron maser , Auroral kilometric radiation, cyclotron maser radiation, PiC code simulation",
author = "Speirs, {D. C.} and Gillespie, {K. M.} and K. Ronald and McConville, {S. L.} and Phelps, {A. D R} and Cross, {A. W.} and R. Bingham and Kellett, {B. J.} and Cairns, {R. A.} and I. Vorgul",
note = "Published in hardcopy : 01/01/2014",
year = "2014",
month = "1",
day = "1",
doi = "10.1088/1742-6596/511/1/012052",
language = "English",
volume = "511",
journal = "Journal of Physics: Conference Series",
issn = "1742-6588",
number = "1",

}

Numerical simulation of unconstrained cyclotron resonant maser emission. / Speirs, D. C.; Gillespie, K. M.; Ronald, K.; McConville, S. L.; Phelps, A. D R; Cross, A. W.; Bingham, R.; Kellett, B. J.; Cairns, R. A.; Vorgul, I.

In: Journal of Physics: Conference Series , Vol. 511, No. 1, 012052, 01.01.2014.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Numerical simulation of unconstrained cyclotron resonant maser emission

AU - Speirs, D. C.

AU - Gillespie, K. M.

AU - Ronald, K.

AU - McConville, S. L.

AU - Phelps, A. D R

AU - Cross, A. W.

AU - Bingham, R.

AU - Kellett, B. J.

AU - Cairns, R. A.

AU - Vorgul, I.

N1 - Published in hardcopy : 01/01/2014

PY - 2014/1/1

Y1 - 2014/1/1

N2 - When a mainly rectilinear electron beam is subject to significant magneticcompression, 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 (AKR) - an intense rf emission sourced at high altitudes in the terrestrial auroral magnetosphere. PiCcode 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 to 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 2.68GHz, 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 radiation emission can be obtained from an electron horseshoe distribution in the absence of radiation boundaries.

AB - When a mainly rectilinear electron beam is subject to significant magneticcompression, 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 (AKR) - an intense rf emission sourced at high altitudes in the terrestrial auroral magnetosphere. PiCcode 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 to 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 2.68GHz, 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 radiation emission can be obtained from an electron horseshoe distribution in the absence of radiation boundaries.

KW - electron beam

KW - electron cyclotron maser

KW - auroral cyclotron maser

KW - Auroral kilometric radiation

KW - cyclotron maser radiation

KW - PiC code simulation

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JO - Journal of Physics: Conference Series

T2 - Journal of Physics: Conference Series

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ER -