The pressure tensor in tangential equilibria

摘要

The tangential equilibria are characterized by a bulk plasma velocityand a magnetic field that are perpendicular to the gradient direction.Such equilibria can be spatially periodic (like waves), or they can separatetwo regions with asymptotic uniform conditions (like MHD tangential discontinuities).It is possible to compute the velocity momentsof 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 inthe frame of the Maxwell-Vlasov theory are significant when the gradientscales are of the order of the Larmor radius; theyconcern mainly the ion pressure tensor.