Adiabatic energy change of plasma electrons and the frame dependence of the cross-shock potential at collisionless magnetosonic shock waves
In collisionless magnetosonic shock waves, ions are commonly thought to be decelerated by dc electrostatic cross-shock electric field along the shock normal n. In a frame where ions are normally incident to the shock the change in the potential energy (qphi/sup N/) in the quasi-perpendicular geommetry is of the order of the change of the energy of normal ion flow: (qphi/sup N/)roughly-equal(1/2m/sub i/(V/sub i//sup N/xn)/sup 2/), which is approximately 200-500 eV at the earth's bow shock. We show that the electron energy gain, typically 1/10 this number, is consistent with such a large potential jump in this geometry. Key facts are the different paths taken by electrons an ions through the shock wave and the frame dependence of the potential jump in the geometry. In the normal incidence frame, electrons lose energy by doing work against the solar wind motional electric field E/sub M//sup N/, which partially offsets the energy gain from the cross-shock electrostatic potential energy (ephi/sub asterisk//sup N/). In the de Hoffman-Teller frame the motional electric field vanishes; the elctrons gain the full electrostatic potential energy jump e(phi/sub asterisk//sup H//sup T/) of that frame, which is not, however, equal to the electrostatic potential energy jump e(phi/sub asterisk//sup N/) of that frame, which is not, however, equal to the electrostatic potential energy jump e(phi/sub asterisk//sup N/) in the normal incidence frame.
- Research Organization:
- Department of Physics and Astronomy, University of Maryland, College Park
- OSTI ID:
- 5999657
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 89:A8
- Country of Publication:
- United States
- Language:
- English
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