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Effect of alpha particles on the shock structure
Author(s) -
Gedalin Michael
Publication year - 2017
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja023460
Subject(s) - shock (circulatory) , physics , amplitude , mechanics , magnetic field , oblique shock , magnetic pressure , plasma , moving shock , atomic physics , compression (physics) , shock wave , classical mechanics , magnetization , nuclear physics , thermodynamics , optics , quantum mechanics , medicine
The magnetic profile of a collisionless shock is shaped by ions. Dynamics of the ions is governed by the fields in the shock front. Species with different charge‐to‐mass ratio have different gyroradii; thus, their distributions upon crossing the shock became substantially different. Accordingly, the dependencies of the density and temperature on the coordinate along the shock normal should differ. In a stable one‐dimensional stationary shock the total pressure must remain constant throughout. Therefore, the magnetic pressure should anticorrelate with the particle pressure. Since the particle pressure is not uniform, downstream spatial magnetic oscillations should arise. Each of the species results in its own dependence of the pressure on the coordinate along the shock normal; therefore, the oscillations are not spatially periodic. The magnetic compression in the shocks with alpha particles is higher than the magnetic compression in purely proton shocks, while the amplitude of the downstream magnetic oscillations is lower.