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Solar Second Harmonic Plasma Emission and the Head-on Approximation

Published online by Cambridge University Press:  25 April 2016

A. J. Willes
Affiliation:
Department of Theoretical Physics and Research Centre for Theoretical Astrophysics, School of Physics, University of Sydney, NSW 2006, Australia. [email protected]
P. A. Robinson
Affiliation:
Department of Theoretical Physics and Research Centre for Theoretical Astrophysics, School of Physics, University of Sydney, NSW 2006, Australia. [email protected]
D. B. Melrose
Affiliation:
Department of Theoretical Physics and Research Centre for Theoretical Astrophysics, School of Physics, University of Sydney, NSW 2006, Australia. [email protected]

Abstract

The coalescence of two Langmuir waves, L and L′, produces emission at twice the plasma frequency in type II and type III solar radio bursts. The analysis of the coalescence process is usually simplified by assuming the head-on approximation, where the wavevectors of the coalescing waves satisfy kL′ ≈ −kL, corresponding to the two Langmuir waves meeting head on. However, this is not always a valid approximation, particularly when the peak of the Langmuir spectrum lies at small wavenumbers, for narrow band spectra, and for spectra with broad angular ranges. Realistic Langmuir wave spectra are used to investigate the effects of relaxing the head-on approximation.

Type
Solar and Solar System
Copyright
Copyright © Astronomical Society of Australia 1995

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