Spatial scales of the magnetic ramp at the Venusian bow shock

A P Dimmock,S N Walker,S A Pope,T L Zhang

doi:10.5194/angeo-29-2081-2011

A P Dimmock, S N Walker + Show 2 more

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https://doi.org/10.5194/angeo-29-2081-2011

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Abstract

Abstract. Typically multi-spacecraft missions are ideally suited to the study of shock spatial scales due to the separation of temporal and spatial variations. These missions are not possible at all locations and therefore in-situ multi-spacecraft measurements are not available beyond the Earth. The present paper presents a study of shock spatial scales using single spacecraft measurements made by the Venus Express spacecraft. The scales are determined based on previous knowledge of shock overshoot scales measured by the ISEE and Cluster missions. The study encompasses around 60 crossings of the Venusian bow shock from 2006 to 2009. The statistical relationship between the shock ramp spatial scales, overshoot and upstream shock parameters are investigated. We find that despite somewhat different solar wind conditions our results are comparable with those based on multi-spacecraft missions at the terrestrial bow shock.

Highlights

Collision-less shocks are one of the core areas of plasma physics research
The purpose of this paper is to explore the spatial scale of the shock ramp and the dependance on the parameters of the quasi-perpendicular shock such as the upstream Alfven Mach number (MA) and the angle between the normal and the upstream magnetic field ( Bn)
The main conclusion that should be draw from this study is that despite the difference in solar wind conditions at the Venusian bow shock, and the absence of any significant intrinsic planetary magnetic field, the spatial scale of the ramp still lies within the same normalised values as studies carried out at the Earth bow shock

Summary

Introduction

Collision-less shocks are one of the core areas of plasma physics research. The dominant process that occurs at the front of a collision-less shock is the redistribution of the upstream plasma bulk kinetic energy into more degrees of freedom and the acceleration of a fragment of the particles into very high energies (Sagdeev, 1966; Sagdeev and Galeev, 1969). The magnetic profile of the collision-less shock has been comprehensively studied in the space environment (Scudder et al, 1986; Farris et al, 1991; Krasnoselskikh et al, 1991; Newbury and Russell, 1996; Balikhin et al, 2002; Bale et al, 2005). Numerical simulations such as those by performed by Leroy et al (1982) have played a critical role in our knowledge of shock structure. There is currently a good understanding of shock structure the roles that small scale structures have on individual dissipation mechanisms at the shock front still remain unclear

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