Optimal Iterative Techniques for Simulation of Plasma Reconnection.

An alternating dimension (1 1/2-D) numerical formulation is used to simulate the slow time, Tokamak scaled (low (beta)) resistive plasma in an oscillating doublet configuration. Convergence is improved by employing a multi-stage iterative technique, Back-Averaging. An optimal Back-Average parameter is used to accelerate convergence to high accuracy. The optimum is obtained by a nonlinear method which controls the dominant eigenvalues of the iteration. By monitoring the magnetic flux inside the separatrix, we investigate magnetic line breaking and reconnection in the adiabatic limit of resistivity, (eta), approaching zero. The results show conclusively that the net reconnected flux, (gamma) is non-zero in the limit as (eta) (--->) 0. This buttresses the assertion of Grad('1) in 1978 that, in a. perfectly conducting plasma, there can be a non -zero reconnected flux. ('1)Grad, H., "Reconnection of Magnetic Lines in an Ideal Fluid," COO-3077-152, MF-92, 1978.