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Evidence for specularly reflected ions upstream from the quasi‐parallel bow shock
Author(s) -
Gosling J. T.,
Thomsen M. F.,
Bame S. J.,
Feldman W. C.,
Paschmann G.,
Sckopke N.
Publication year - 1982
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl009i012p01333
Subject(s) - physics , specular reflection , solar wind , ion , bow shock (aerodynamics) , bow wave , shock (circulatory) , reflection (computer programming) , guiding center , shock wave , upstream (networking) , computational physics , fermi acceleration , magnetopause , magnetic field , atomic physics , particle acceleration , geophysics , optics , acceleration , mechanics , classical mechanics , medicine , computer network , quantum mechanics , computer science , programming language
Ion velocity distributions in the form of bunches of gyrating particles traveling along helical paths have been observed moving sunward immediately upstream from quasi‐parallel parts of the earth's bow shock using Los Alamos/Garching instruments on ISEE‐1 and ‐2. These distributions have characteristics which indicate that they are produced by the nearly specular reflection at the shock of a portion of the incident solar wind ions. In particular, the guiding center motion and the gyrospeeds of the gyrating ions are quantitatively consistent with simple geometrical considerations for specular reflection. These considerations reveal that specularly reflected ions can escape upstream for θ Bn < 45° but not for θ Bn > 45° (where θ Bn is the angle between the upstream magnetic field, B, and the local shock normal ). These upstream gyrating ions are an important signature of one of the processes by which solar wind streaming energy is dissipated into other forms of energy at the shock.