A NEW FORM OF THE MAGNETOHYDRODYNAMIC POTENTIAL-ENERGY

In this Letter a useful and instructive form of the magnetohydrodynami c potential energy is presented. In this form all but one term is posi tive definite, each term is self-adjoint, and it can be directly evalu ated numerically in nonorthogonal coordinate systems. The product of t he local shear and the current parallel to the magnetic field is ident ified as a significant parameter for current-driven instabilities. (C) 1996 American Institute of Physics.