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Scale lengths in quasi‐parallel shocks
Journal article   Peer reviewed

Scale lengths in quasi‐parallel shocks

J. D Scudder, L. F Burlaga and E. W Greenstadt
Journal of Geophysical Research: Space Physics, Vol.89(A9), pp.7545-7550
09/01/1984
DOI: 10.1029/JA089iA09p07545

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Abstract

Examples of an interplanetary shock and the earth's bow shock are presented to illustrate the small‐scale size Lp of the fluid deceleration relative to the scale of the magnetic fluctuations, LM, at quasi‐parallel shocks. The increase in electron and ion random energies is also illustrated to occur on the short “inner” scale of Lp. The selected interplanetary and bow shock examples are both supercritical high‐β shocks but have different Alfvén Mach numbers. The thickness Lp in absolute and convected Larmor radii units of the lower Alfvén Mach number interplanetary shock is larger (∼10 U′/Ωci) than that at the bow shock (∼(1–2) U′/Ωci), where U′ is the plasma flow speed viewed in the normally incident shock rest frame. In both examples the scale of the fluid deceleration is much smaller than that of the up‐ or downstream magnetic fluctuations. The existence of steady state quasi‐parallel shocks requires that the Lorentz deceleration force be much larger than the electrostatic deceleration force along the shock normal.

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