Evaluating the de Hoffmann-Teller cross-shock potential at real collisionless shocks Journal Article uri icon

Overview

abstract

  • Shock waves are common in the heliosphere and beyond. The collisionless; nature of most astrophysical plasmas allows for the energy processed by; shocks to be partitioned amongst particle sub-populations and; electromagnetic fields via physical mechanisms that are not well; understood. The electrostatic potential across such shocks is frame; dependent. In a frame where the incident bulk velocity is parallel to; the magnetic field, the deHoffmann-Teller frame, the potential is linked; directly to the ambipolar electric field established by the electron; pressure gradient. Thus measuring and understanding this potential; solves the electron partition problem, and gives insight into other; competing shock processes. Integrating measured electric fields is space; is problematic since the measurements can have offsets that change with; plasma conditions. The offsets, once integrated, can be as large or; larger than the shock potential. Here we exploit the high-quality field; and plasma measurements from NASA's Magnetospheric Multiscale mission to; attempt this calculation. We investigate recent adaptations of the; deHoffmann-Teller frame transformation to include time variability, and; conclude that in practise these face difficulties inherent in the 3D; time-dependent nature of real shocks by comparison to 1D simulations.; Potential estimates based on electron fluid and kinetic analyses provide; the most robust measures of the deHoffmann-Teller potential, but with; some care direct integration of the electric fields can be made to; agree. These results suggest that it will be difficult to independently; assess the role of other processes, such as scattering by shock; turbulence, in accounting for the electron heating.

publication date

  • March 2, 2021

has restriction

  • bronze

Date in CU Experts

  • May 19, 2021 2:11 AM

Full Author List

  • Schwartz SJ; Ergun RE; Harald K; Wilson LB; Chen L-J; Goodrich KA; Turner DL; Gingell I; Madanian H; Gershman DJ

author count

  • 11

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