Nonlinear dependence of ion-acoustic anomalous resistivity on electron drift velocity

Petkaki, P.; Freeman, M.P.. 2008 Nonlinear dependence of ion-acoustic anomalous resistivity on electron drift velocity. Astrophysical Journal, 686 (1). 686-693. 10.1086/590654

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Collisionless magnetic reconnection requires the violation of ideal MHD by various kinetic-scale effects. Recent research has highlighted the potential importance of wave-particle interactions by showing that Vlasov simulations of unstable ion-acoustic waves predict an anomalous resistivity that can be significantly higher in the nonlinear regime than the quasi-linear estimate. Here, we investigate the dependence on the initial electron drift velocity of the current driven ion-acoustic instability and its resulting anomalous resistivity. We examine the properties of statistical ensembles of 10 Vlasov simulations with real mass ratios for a range of drift velocities and for electron to ion temperature ratios of 0.9, 1, and 2, relevant to both solar and magnetospheric physics. We show that the ion-acoustic anomalous resistivity depends nonlinearly on the electron drift velocity for the low temperature ratios examined, in contrast to the linear dependence predicted by theory and commonly assumed in models of magnetic reconnection. Specifically we find that (1) anomalous resistivity is a power-law function of the electron drift velocity ( ), approximately with exponent , and (2) anomalous resistivity is a power-law function of the normalized drift velocity ( , approximately with exponent . An anomalous resistivity model consistent with our results could be important for simulations of magnetic reconnection in astrophysical plasmas.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1086/590654
Programmes: BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Natural Complexity Programme
ISSN: 0004-637X
Additional Keywords: ion-acoustic instability, anomalous resistivity, power law, magnetic reconnection
NORA Subject Terms: Physics
Space Sciences
Date made live: 20 Jan 2009 11:03 +0 (UTC)

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