FILAMENTARY MAGNETOHYDRODYNAMIC PLASMAS

A filamentary construct of magnetohydrodynamical plasma dynamics based on the Elsasser variables is developed. This approach is modeled afte r discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to those based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and wh en this force is neglected, the plasma vortex system is described by a Hamiltonian. A statistical treatment of a collection of discrete curr ent-vorticity concentrations is given. Canonical and microcanonical st atistical calculations show that both the vorticity and;the current sp ectra are peaked at long wavelengths, and the expected states revert t o known hydrodynamical states as the magnetic field vanishes. These re sults differ from previous Fourier-based statistical theories, but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the l ow-temperature limit, and the previous Hamiltonian plasma vortex resul ts in the high-temperature limit. Numerical simulations of a large num ber of filaments are carried out and support the theory. A three-dimen sional vortex model is presented as well, which is also Hamiltonian wh en the inductive force is neglected. A statistical calculation in the canonical ensemble and numerical simulations show that a nonzero large -scale magnetic field is statistically favored, and that the preferred shape of this field is a long, thin tube of flux. Possible applicatio ns to a variety of physical phenomena are suggested.