Laboratory astrophysics : investigation of planetary and astrophysical maser emission

Bingham, R. and Speirs, D.C. and Kellett, B.J. and Vorgul, I. and McConville, S.L. and Cairns, R.A. and Cross, A.W. and Phelps, A.D.R. and Ronald, K. (2013) Laboratory astrophysics : investigation of planetary and astrophysical maser emission. Space Science Reviews, 178 (2-4). pp. 695-713. ISSN 0038-6308 (https://doi.org/10.1007/s11214-013-9963-z)

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Abstract

This paper describes a model for cyclotron maser emission applicable to planetary auroral radio emission, the stars UV Ceti and CU Virginus, blazar jets and astrophysical shocks. These emissions may be attributed to energetic electrons moving into convergent magnetic fields that are typically found in association with dipole like planetary magnetospheres or shocks. It is found that magnetic compression leads to the formation of a velocity distribution having a horseshoe shape as a result of conservation of the electron magnetic moment. Under certain plasma conditions where the local electron plasma frequency ω is much less than the cyclotron frequency ω the distribution is found to be unstable to maser type radiation emission. We have established a laboratory-based facility that has verified many of the details of our original theoretical description and agrees well with numerical simulations. The experiment has demonstrated that the horseshoe distribution produces cyclotron emission at a frequency just below the local electron cyclotron frequency, with polarisation close to X-mode and propagating nearly perpendicularly to the electron beam motion. We discuss recent developments in the theory and simulation of the instability including addressing radiation escape problems, and relate these to the laboratory, space, and astrophysical observations. The experiments showed strong narrow band EM emissions at frequencies just below the cold-plasma cyclotron frequency as predicted by the theory. Measurements of the conversion efficiency, mode and spectral content were in close agreement with the predictions of numerical simulations undertaken using a particle-in-cell code and also with satellite observations confirming the horseshoe maser as an important emission mechanism in geophysical/astrophysical plasmas. In each case we address how the radiation can escape the plasma without suffering strong absorption at the second harmonic layer.

ORCID iDs

Bingham, R. ORCID logoORCID: https://orcid.org/0000-0002-9843-7635, Speirs, D.C. ORCID logoORCID: https://orcid.org/0000-0001-5705-6126, Kellett, B.J., Vorgul, I., McConville, S.L., Cairns, R.A., Cross, A.W. ORCID logoORCID: https://orcid.org/0000-0001-7672-1283, Phelps, A.D.R. ORCID logoORCID: https://orcid.org/0000-0002-1100-1012 and Ronald, K. ORCID logoORCID: https://orcid.org/0000-0002-8585-0746;
  • Item type:Article
    ID code:53046
    Dates:
    Date
    Event
    October 2013
    Published
    8 March 2013
    Published Online
    Notes:First published online on publisher's website on 8 March 2013; hardcopy paper published in journal October 2013, Volume 178, Issue 2-4, pp. 695-713.
    Subjects:Science > Astronomy
    Science > Physics
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:21 May 2015 15:55
    Last modified:11 Nov 2024 10:30
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/53046
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