Electrostatic shock properties inferred from AKR fine structure
- 1CETP-CNRS, 4 Rue de Neptune, F-94107 Saint-Maur des Fossés, France
- 2Centre for Interdisciplinary Plasma Science, Max-Planck-Institute for extraterrestrial Physics, P.O.Box 1312, D-85748 Garching, Germany. Also at International Space Science Institute, Hallerstr. 6, CH-3012 Bern, Switzerland
- 3Space Sciences Laboratory, University of California, Berkeley, CA94720-7450, USA. On leave from CETP
- 4Air Force Research Laboratory, Hanscom Air Force Base, MA01731-3010, USA
Abstract. The auroral kilometric radiation (AKR) consists of a large number of fast drifting elementary radiation events that have been interpreted as travelling electron holes resulting from the nonlinear evolution of electron-acoustic waves. The elementary radiation structures sometimes become reflected or trapped in slowly drifting larger structures where the parallel electric fields are located. These latter features have spectral frequency drifts which can be interpreted in terms of the propagation of shock-like disturbances along the auroral field line at velocities near the ion-acoustic speed. The amplitude, speed, and shock width of such localized ion-acoustic shocks are determined here in the fluid approximation from the Sagdeev potential, assuming realistic plasma parameters. It is emphasized that the electrostatic potentials of such nonlinear structures contribute to auroral acceleration.