Reversed-field pinch dynamics and transport studies

Progress in RFP dynamics and transport studies is described. A three dimensional, incompressible MHD code was developed, and is being checked against known results. It is computationally more efficient than the existing code, and will be used extensively if compressibility is determined to be unimportant. Post processor codes to analyze data generated by the nonlinear code were developed. Three dimensional computer runs at low theta(=B/sub theta/(a)/,B/sub z/) have found the development of a substantial stochastic core, with good flux surfaces being retained in the outer part of the discharge. Runs at high theta have shown complete stochasticity, with reappearance of outer flux surfaces as the modes saturate and relax. Anomalous maintenance of positive toroidal flux arising from a poloidal electric field at the field reversal surface induced by MHD fluctuations (dynamo) was observed. These results were documented in a publication. Statistical analysis of stochastic magnetic field regions to assess transport coefficients is underway.