Analysis of macro- and micro-turbulence within quasi perpendicular supercritical shocks via numerical simulation.

Bertrand Lembège 1
1 HEPPI - LATMOS
LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
Abstract : Recent numerical simulations and experimental results have clearly evidenced that shock front of quasi perpendicular shocks can be strongly nonstationary. Different processes of nonstionarity have been identified thanks to numerical simulations. One major difficulty is that these different processés strongly compete each other within the shock front region (according to the Mach regime, direction of propagation, upstream plasma parameters, approach to more realistic conditions ) and are strongly mixed including quite different time/spatial scales. A tentative approach for overcoming such a difficulty consists in classifying all these processes into two groups. The first group gathers the processes due to the variations of macroscopic field at the front only (without invoking microinstabilities). Main features are that characteristic time scale is on the ion scale (or a part of it), while typical spatial scale of the ramp can strongly varies from a part of ion scale to the electron scale. The second group is only based on microinstabilities. The striking features are that the characteristics scale of nonstationarity varies from ion and hybrid scales (between ion and electron scale) to a few tens of Debye lengths as shown recently. This presentation will illustrate how this classification can influence the analysis of experimental results, in order to identify the features of some underlying nonstationary processes.
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Submitted on : Wednesday, December 26, 2012 - 9:44:06 PM
Last modification on : Tuesday, May 14, 2019 - 11:09:50 AM

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  • HAL Id : hal-00768957, version 1

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Bertrand Lembège. Analysis of macro- and micro-turbulence within quasi perpendicular supercritical shocks via numerical simulation.. AGU Fall Meeting, Dec 2012, San Francisco, United States. ⟨hal-00768957⟩

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