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Quasi‐parallel shocks: A patchwork of three‐dimensional structures
Author(s) -
Schwartz Steven J.,
Burgess David
Publication year - 1991
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 - 10.1029/91gl00138
Subject(s) - physics , shock (circulatory) , amplitude , foreshock , magnetic field , upstream (networking) , geophysics , shock wave , transverse plane , flow (mathematics) , boundary (topology) , spacecraft , kinetic energy , bow shock (aerodynamics) , computational physics , mechanics , geology , classical mechanics , seismology , optics , astronomy , computer science , aftershock , mathematics , medicine , computer network , mathematical analysis , structural engineering , engineering , quantum mechanics
Collisionless shocks at quasi‐parallel geometries, i.e., for which the average magnetic field direction upstream of the shock is close to the shock normal, reveal temporally varying quantities, a variety of boundary crossing and kinetic signatures, and magnetic structures, often convecting, of finite extent. These results can be put together by a framework in which the shock can be viewed as an extended region containing three‐dimensional Short Large Amplitude Magnetic Structures (SLAMS) which represent individual semi‐cycles of the ambient upstream low frequency waves associated with diffuse ions in the ULF foreshock. As SLAMS convect with the flow they grow to large amplitudes and entrain inter‐SLAMS regions to form an inhornogeneous downstream state. Their finite transverse extent is probably related to, and interacts with, ion beams, to produce a patchy transition zone which accounts for the variety of spacecraft signatures observed.