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Investigation of plasma instabilities in the Polar cuspDuring the last six months, our efforts concentrated on studying the excitation of electromagnetic waves in the whistler frequency range by an anisotropic electron beam. A paper entitled 'Electron Cyclotron Wave Generation by Relativistic Electrons' was submitted to Journal of Geophysical Research and was accepted for publication. This paper is in collaboration with Dr. M. L. Goldstein at Goddard Space Flight Center. It was shown that an anisotropic electron beam (or gyrating electron beam) is capable of generating electron cyclotron waves with frequency from above to below the electron plasma frequency in a low density plasma. This instability may account for the observed Z mode and the electromagnetic component of auroral hiss in the Earth's polar region. The abstract of this paper is enclosed. For a high density plasma in which the electron plasma frequency is considerably higher than the electron cyclotron frequency, a new left-hand electromagnetic wave at whistler frequencies, which is also driven unstable by an anisotropic electron beam, was found. The basic notion of this new instability is the significant change of the dispersion equation due to the contribution of the beam component, which can shift the usual right hand whistler waves into left hand waves.
Document ID
19940008611
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Wong, H. K. (Southwest Research Inst. San Antonio, TX, United States)
Date Acquired
September 6, 2013
Publication Date
August 31, 1993
Subject Category
Plasma Physics
Report/Patent Number
NASA-CR-194283
NAS 1.26:194283
Accession Number
94N13084
Funding Number(s)
PROJECT: SWRI PROJ. 15-2779
CONTRACT_GRANT: NAGW-1620
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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