Numerical simulation of auroral cyclotron maser processes

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

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Results are presented from a numerical investigation of radiation emission from an electron beam with a horseshoe-shaped velocity distribution. This process is relevant to the phenomenon of auroral kilometric radiation (AKR) which occurs in the polar regions of the Earth's magnetosphere. In these regions of the auroral zone, particles accelerated into the increasing magnetic field of the Earth's dipole develop a horseshoe-shaped velocity distribution through conservation of magnetic moment. It has been shown theoretically that this distribution is unstable to a cyclotron maser instability. A 2D particle-in-cell (PIC) code model was constructed to simulate a scaled laboratory experiment in which an electron beam subject to significant magnetic compression may be studied and brought into resonance with TE modes of an interaction waveguide. Results were obtained for electron beam energies of 75-85 keV, magnetic compression factors of up to 30 and electron cyclotron frequencies of 4.42 and 11.7 GHz. At 11.7 GHz, beam-wave coupling was observed with the TE03 mode and an RF output power of 20 kW was obtained corresponding to an RF conversion efficiency of 1.3%. At 4.42 GHz, excitation of the TE01 mode was observed with an RF output power of 35 kW for a cyclotron-wave detuning of 2%. This corresponds to an RF conversion efficiency of 2.6%. In both cases PiC particle velocity distributions show the clear formation of a horseshoe-shaped velocity distribution and subsequent action of a cyclotron maser instability. The RF conversion efficiencies obtained are also comparable with estimates for the AKR generation efficiency. (Abstract from: http://iopscience.iop.org/0741-3335/50/7/074011/)
Original languageEnglish
Article number074011
Number of pages15
JournalPlasma Physics and Controlled Fusion
Volume50
Issue number7
Early online date3 Jun 2008
DOIs
Publication statusPublished - Jul 2008

Fingerprint

Masers
Cyclotrons
masers
Velocity distribution
cyclotrons
velocity distribution
magnetic compression
Conversion efficiency
Electron beams
Computer simulation
electron beams
Radiation
radiation
simulation
Earth (planet)
Magnetosphere
auroral zones
Earth magnetosphere
output
cyclotron frequency

Keywords

  • numerical simulation
  • auroral cyclotron maser processes

Cite this

Speirs, David ; McConville, S.L. ; Gillespie, K.M. ; Ronald, K. ; Phelps, A.D.R. ; Cross, A.W. ; Bingham, R. ; Robertson, C.W. ; Whyte, C.G. ; Vorgul, I. ; Cairns, R.A. ; Kellett, B.J. / Numerical simulation of auroral cyclotron maser processes. In: Plasma Physics and Controlled Fusion. 2008 ; Vol. 50, No. 7.
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abstract = "Results are presented from a numerical investigation of radiation emission from an electron beam with a horseshoe-shaped velocity distribution. This process is relevant to the phenomenon of auroral kilometric radiation (AKR) which occurs in the polar regions of the Earth's magnetosphere. In these regions of the auroral zone, particles accelerated into the increasing magnetic field of the Earth's dipole develop a horseshoe-shaped velocity distribution through conservation of magnetic moment. It has been shown theoretically that this distribution is unstable to a cyclotron maser instability. A 2D particle-in-cell (PIC) code model was constructed to simulate a scaled laboratory experiment in which an electron beam subject to significant magnetic compression may be studied and brought into resonance with TE modes of an interaction waveguide. Results were obtained for electron beam energies of 75-85 keV, magnetic compression factors of up to 30 and electron cyclotron frequencies of 4.42 and 11.7 GHz. At 11.7 GHz, beam-wave coupling was observed with the TE03 mode and an RF output power of 20 kW was obtained corresponding to an RF conversion efficiency of 1.3{\%}. At 4.42 GHz, excitation of the TE01 mode was observed with an RF output power of 35 kW for a cyclotron-wave detuning of 2{\%}. This corresponds to an RF conversion efficiency of 2.6{\%}. In both cases PiC particle velocity distributions show the clear formation of a horseshoe-shaped velocity distribution and subsequent action of a cyclotron maser instability. The RF conversion efficiencies obtained are also comparable with estimates for the AKR generation efficiency. (Abstract from: http://iopscience.iop.org/0741-3335/50/7/074011/)",
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Numerical simulation of auroral cyclotron maser processes. / Speirs, David; McConville, S.L.; Gillespie, K.M.; Ronald, K.; Phelps, A.D.R.; Cross, A.W.; Bingham, R.; Robertson, C.W.; Whyte, C.G.; Vorgul, I.; Cairns, R.A.; Kellett, B.J.

In: Plasma Physics and Controlled Fusion, Vol. 50, No. 7, 074011 , 07.2008.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Numerical simulation of auroral cyclotron maser processes

AU - Speirs, David

AU - McConville, S.L.

AU - Gillespie, K.M.

AU - Ronald, K.

AU - Phelps, A.D.R.

AU - Cross, A.W.

AU - Bingham, R.

AU - Robertson, C.W.

AU - Whyte, C.G.

AU - Vorgul, I.

AU - Cairns, R.A.

AU - Kellett, B.J.

PY - 2008/7

Y1 - 2008/7

N2 - Results are presented from a numerical investigation of radiation emission from an electron beam with a horseshoe-shaped velocity distribution. This process is relevant to the phenomenon of auroral kilometric radiation (AKR) which occurs in the polar regions of the Earth's magnetosphere. In these regions of the auroral zone, particles accelerated into the increasing magnetic field of the Earth's dipole develop a horseshoe-shaped velocity distribution through conservation of magnetic moment. It has been shown theoretically that this distribution is unstable to a cyclotron maser instability. A 2D particle-in-cell (PIC) code model was constructed to simulate a scaled laboratory experiment in which an electron beam subject to significant magnetic compression may be studied and brought into resonance with TE modes of an interaction waveguide. Results were obtained for electron beam energies of 75-85 keV, magnetic compression factors of up to 30 and electron cyclotron frequencies of 4.42 and 11.7 GHz. At 11.7 GHz, beam-wave coupling was observed with the TE03 mode and an RF output power of 20 kW was obtained corresponding to an RF conversion efficiency of 1.3%. At 4.42 GHz, excitation of the TE01 mode was observed with an RF output power of 35 kW for a cyclotron-wave detuning of 2%. This corresponds to an RF conversion efficiency of 2.6%. In both cases PiC particle velocity distributions show the clear formation of a horseshoe-shaped velocity distribution and subsequent action of a cyclotron maser instability. The RF conversion efficiencies obtained are also comparable with estimates for the AKR generation efficiency. (Abstract from: http://iopscience.iop.org/0741-3335/50/7/074011/)

AB - Results are presented from a numerical investigation of radiation emission from an electron beam with a horseshoe-shaped velocity distribution. This process is relevant to the phenomenon of auroral kilometric radiation (AKR) which occurs in the polar regions of the Earth's magnetosphere. In these regions of the auroral zone, particles accelerated into the increasing magnetic field of the Earth's dipole develop a horseshoe-shaped velocity distribution through conservation of magnetic moment. It has been shown theoretically that this distribution is unstable to a cyclotron maser instability. A 2D particle-in-cell (PIC) code model was constructed to simulate a scaled laboratory experiment in which an electron beam subject to significant magnetic compression may be studied and brought into resonance with TE modes of an interaction waveguide. Results were obtained for electron beam energies of 75-85 keV, magnetic compression factors of up to 30 and electron cyclotron frequencies of 4.42 and 11.7 GHz. At 11.7 GHz, beam-wave coupling was observed with the TE03 mode and an RF output power of 20 kW was obtained corresponding to an RF conversion efficiency of 1.3%. At 4.42 GHz, excitation of the TE01 mode was observed with an RF output power of 35 kW for a cyclotron-wave detuning of 2%. This corresponds to an RF conversion efficiency of 2.6%. In both cases PiC particle velocity distributions show the clear formation of a horseshoe-shaped velocity distribution and subsequent action of a cyclotron maser instability. The RF conversion efficiencies obtained are also comparable with estimates for the AKR generation efficiency. (Abstract from: http://iopscience.iop.org/0741-3335/50/7/074011/)

KW - numerical simulation

KW - auroral cyclotron maser processes

U2 - 10.1088/0741-3335/50/7/074011

DO - 10.1088/0741-3335/50/7/074011

M3 - Article

VL - 50

JO - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

SN - 0741-3335

IS - 7

M1 - 074011

ER -