The time evolution of a slightly non-ideal neutral plasma

The concept of a slightly non-ideal plasma was first introduced by J. B. Taylor in the context of his famous theory on plasma relaxation in the following sense: a slightly non-ideal plasma relaxes towards a state of minimum magnetic energy under the constraint that the global magnetic helicity integral and the total toroidal magnetic flux remain conserved. Based on a multiple time-scale derivative expansion scheme, we have shown in a previous work, that Taylor's conjecture is indeed tine on the MHD-collision time-scale (CMHD). In this paper, the invariance properties of both the local and the global mass integrals are investigated on the ideal MHD (IMHD) and the CMHD time-scales. On the IMHD time-scale, it is shown that both the local and the global mass integrals are conserved. On the CMHD time-scale, it turns out that the local mass integral is no longer conserved while, on account of the motion of the particles across the magnetic field lines, the global mass integral is only conserved