STABILITY OF FORCE-FREE TAYLOR STATES IN A NEW VERSION OF MAGNETIC FLUX-AVERAGED MAGNETOHYDRODYNAMICS

It is observed that the recently developed magnetic flux-averaged magn etohydrodynamics (AMHD) [Phys. Plasmas 1, 2488 (1994)] is incompatible with Taylor's theorem, which states that the lowest-energy state of f orce-free equilibria based on the conservation of the helicity integra l is absolutely stable for vanishingly small resistivity. By a modific ation of the Lagrangian from which AMHD is derived, a modified version of AMHD that is compatible with Taylor's theorem is obtained. It also provides an energy principle for examining the linear instability of resistive equilibria, which has a great advantage over resistive MHD. (C) 1996 American Institute of Physics.