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Persistent URL http://purl.org/net/epubs/work/64158
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Record Id 64158
Title Laboratory astrophysics : investigation of planetary and astrophysical maser emission
Abstract This paper describes a new model for cyclotron maser emission from space and astrophysical objects such as magnetised planets and stars. These emissions are attributed to energetic electrons moving into convergent magnetic fields that are typically found in association with dipole like planetary / stellar 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 ωpe is much less than the cyclotron frequency ωce 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 polarization 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 the effect of competing instabilities, relating 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 the auroral region.
Organisation CLF , STFC
Keywords cyclotron maser radiation; , Auroral kilometric radiation; , plasma instabilities.
Funding Information
Related Research Object(s): 11833424
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Language English (EN)
Type Details URI(s) Local file(s) Year
Journal Article Space Sci Rev 178, no. 2-4 (2013): 695-713. doi:10.1007/s11214-013-9963-z 2013