ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-22-3033-2004 The pressure tensor in tangential equilibria Mottez F. 1 Centre d’études des Environnements Terrestre et Planétaires, CETP/IPSL/CNRS, Vélizy, France 07 09 2004 22 8 3033 3037 Copyright: © 2004 F. Mottez 2004 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/22/3033/2004/angeo-22-3033-2004.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/22/3033/2004/angeo-22-3033-2004.pdf

The tangential equilibria are characterized by a bulk plasma velocity and a magnetic field that are perpendicular to the gradient direction. Such equilibria can be spatially periodic (like waves), or they can separate two regions with asymptotic uniform conditions (like MHD tangential discontinuities). It is possible to compute the velocity moments of the particle distribution function. Even in very simple cases, the pressure tensor is not isotropic and not gyrotropic. The differences between a scalar pressure and the pressure tensor derived in the frame of the Maxwell-Vlasov theory are significant when the gradient scales are of the order of the Larmor radius; they concern mainly the ion pressure tensor.