Modification of the solar wind electron velocity distribution at interplanetary shocks

Abstract

We analyze a small selection of interplanetary shocks of moderate strength, observed by instruments aboard the Wind spacecraft: We find electron signatures of heating and acceleration that are similar to those found at Earth's high Mach number bow shock. Upstream, velocity distributions have the signature of shock-accelerated electrons with the characteristic time of flight velocity cutoff with bump-on-tail reduced distributions observed in coincidence with Langmuir waves. Downstream, the distributions broaden with the stronger shocks showing flat-topped distributions and accompanying beams, such as are seen on the high entropy side of Earth's bow shock. We apply the Liouville mapping analysis of Hull et al. [1998, 2001] to one of the interplanetary shocks and compute the deHoffman-Teller electrostatic potential across the shock using the electron moments to map the observed upstream distribution to the downstream region. The mapping successfully reproduces the inflated phase density and beam signatures of the observed downstream electron velocity distribution. Copyright 2003 by the American Geophysical Union.