Contributions to the cross shock electric field at a quasiperpendicular collisionless shock

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Abstract

[1] The normal electric field structure of a supercritical (Mms = 5.2), quasiperpendicular (θBn = 70°) collisionless shock is examined using Cluster four-spacecraft observations of the terrestrial bow shock. Comparing the observed electric field with magnetic field and plasma observations, two different techniques find that the J × B/ne term in the generalized Ohm's law accounts for a majority of the large-scale normal electric field and potential drop encountered by the ions - the solar wind ion deceleration is in good empirical agreement with the observed potential drop, confirming earlier work. Large amplitude electric field fluctuations on shorter timescales, corresponding to fine scale structure, are not observed to contribute to the ion energization.

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