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Title: Proton beam generation of oblique whistler waves

Journal Article · · Journal of Geophysical Research; (United States)
 [1];  [2]
  1. Southwest Research Inst., San Antonio, TX (United States)
  2. NASA Goddard Space Flight Center, Greenbelt, MD (United States)

It is known that ion beams are capable of generating whistler waves that propagate parallel to the mean magnetic field {und B}{sub o}. Such waves may have been observed both upstream of the Earth's bow shock and in the vicinity of comets. The authors extend previous analyses to include propagation oblique to {und B}{sub 0}. The instability is generated by the perpendicular component of free energy in the ions; which can arise either via a temperature anisotropy (T{sub perpendicular}/T{sub parallel} {much gt} 1) or via a gyrating distribution. In the former case the generation of whistler waves is confined to a fairly narrow cone of propagation directions centered about parallel propagation; while in the latter case, the maximum growth of the instability can occur at fairly large obliquities ({theta} {congruent} 50{degree}).

OSTI ID:
5962305
Journal Information:
Journal of Geophysical Research; (United States), Vol. 93:A5; ISSN 0148-0227
Country of Publication:
United States
Language:
English