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Title: Analysis of a cyclotron maser instability in cylindrical geometry

Abstract

Cyclotron maser instability is known to be one of the main mechanisms of coherent radio emission in space and laboratory plasmas. This paper investigates a particular case of such an instability induced by a horseshoe- or crescent-shaped electron velocity distribution function, which is produced when an electron beam propagates in a convergent magnetic field, whether it is Earth's magnetic field or one introduced in a laboratory experiment. The instability is analyzed in cylindrical geometry which is relevant to auroral kilometric radiation and to a laboratory experiment. Exact modeling of TE and TM anisotropic modes for circular electronic beam shows its high growth rate for modes with almost perpendicular propagation.

Authors:
; ;  [1];  [2]
  1. School of Mathematics and Statistics, University of St Andrews, Saint Andrews, Fife KY16 9SS (United Kingdom)
  2. (United Kingdom)
Publication Date:
OSTI Identifier:
20782402
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 12; Journal Issue: 12; Other Information: DOI: 10.1063/1.2139506; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ANISOTROPY; BEAM-PLASMA SYSTEMS; COMPUTERIZED SIMULATION; CYLINDRICAL CONFIGURATION; DISTRIBUTION FUNCTIONS; ELECTRON BEAMS; ELECTRONS; EMISSION; GEOMETRY; MAGNETIC FIELDS; MASERS; PLASMA; PLASMA INSTABILITY; PLASMA SIMULATION

Citation Formats

Vorgul, I., Cairns, R.A., Bingham, R., and CCLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX. Analysis of a cyclotron maser instability in cylindrical geometry. United States: N. p., 2005. Web. doi:10.1063/1.2139506.
Vorgul, I., Cairns, R.A., Bingham, R., & CCLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX. Analysis of a cyclotron maser instability in cylindrical geometry. United States. doi:10.1063/1.2139506.
Vorgul, I., Cairns, R.A., Bingham, R., and CCLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX. Thu . "Analysis of a cyclotron maser instability in cylindrical geometry". United States. doi:10.1063/1.2139506.
@article{osti_20782402,
title = {Analysis of a cyclotron maser instability in cylindrical geometry},
author = {Vorgul, I. and Cairns, R.A. and Bingham, R. and CCLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX},
abstractNote = {Cyclotron maser instability is known to be one of the main mechanisms of coherent radio emission in space and laboratory plasmas. This paper investigates a particular case of such an instability induced by a horseshoe- or crescent-shaped electron velocity distribution function, which is produced when an electron beam propagates in a convergent magnetic field, whether it is Earth's magnetic field or one introduced in a laboratory experiment. The instability is analyzed in cylindrical geometry which is relevant to auroral kilometric radiation and to a laboratory experiment. Exact modeling of TE and TM anisotropic modes for circular electronic beam shows its high growth rate for modes with almost perpendicular propagation.},
doi = {10.1063/1.2139506},
journal = {Physics of Plasmas},
number = 12,
volume = 12,
place = {United States},
year = {Thu Dec 15 00:00:00 EST 2005},
month = {Thu Dec 15 00:00:00 EST 2005}
}
  • This paper presents a quasilinear analysis of the relativistic electron cyclotron maser instability. Two electron populations are assumed: a low-temperature background component and a more energetic loss-cone population. The dispersion relation is valid for any ratio of the energetic to cold populations, and includes thermal and relativistic effects. The quasilinear analysis is based upon an efficient kinetic moment method, in which various moment equations are derived from the particle kinetic equation. A model time-dependent loss-cone electron distribution function is assumed, which allows one to evaluate the instantaneous linear growth rate as well as the moment kinetic equations. These moment equationsmore » along with the wave kinetic equation form a fully self-consistent set of equations which governs the evolution of the particles as well as unstable waves. This set of equations is solved with physical parameters typical of the earth`s auroral zone plasma. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.« less
  • The temporal evolution of the linear diocotron instability of the cylindrical annular plasma column is investigated by employing the extension of the shearing modes methodology to the cylindrical geometry. It was obtained that the spatial time-dependent distortion of the electron density initial perturbations by shear flows leads to the non-modal evolution of the potential, which was referred to as the manifestation of the continuous spectrum. The evolution process leads toward the convergence to the phase-locking configuration of the mutually growing normal modes.
  • The temporal evolution of the linear diocotron instability of a cylindrical annular plasma column surrounded by a conducting boundary has been investigated by using the methodology of the cylindrical shearing modes. The linear solution of the initial and boundary-value problems is obtained which is valid for any time at which linear effects dominate. The solution reveals that the initial perturbations of the electron density pass through the stage of the non-modal evolution when the perturbation experiences spatio-temporal distortion pertinent to the considered geometry of the electron column. The result is confirmed by a two-dimensional cylindrical particle-in-cell simulation.
  • It is shown that the electron-cyclotron maser instabilities may readily be excited in a plasma with a loss-cone distribution when the electron temperature exceeds a few tens of kiloelectronvolts. The growth rate is typically a few percent of the electron-cyclotron frequency. The appearance of the instability can be avoided by proper control of the plasma density.
  • A self-consistent theory of cyclotron maser instability is developed for azimuthally symmetric perturbations about the equilibrium of an intense slowly rotating hollow beam that propagates at a certain axial velocity parallel to a uniform magnetic field. The stability analysis is carried out within the framework of the linearized Vlasov-Maxwell equations for an infinitely long beam (propagating parallel to a uniform magnetic field). The positive ions are assumed to form an immobile partially neutralized background. It is further assumed that the electron beam is thin, i.e., that the radial thickness is small in comparison with the mean radius. It is shownmore » that the TE mode corresponds to the most unstable propagation.« less