The role of magnetic reconnection and differential rotation in spheromak formation.

The physical processes involved in the formation of a spheromak are studied. Using one-fluid axisymmetric resistive magnetohydrodynamic equations together with a temperature equation, investigations of the essential physics aspects of the formation specifically for the new Maryland Spheromak (MS) [J. Antoniades, C. Chin-Fatt, A. DeSilva, G. Goldenbaum, R. Hess, and R. Shaw, in Proceedings of the Sixth U. S. Symposium on Compact Torus Research, Princeton, 1984 (Princeton Plasma Physics Laboratory, Princeton, NJ, 1985), p. 65] have been performed. These studies elucidate the role of differential rotation in accelerating the penetration of toroidal field B[lowercase_phi_synonym] and in forcing I≡ rB[lowercase_phi_synonym] to be a flux function. Another important aspect of the formation is the magnetic reconnection that occurs at the X point between the two reversal coils. A strong toroidal current is generated by the reconnection, and the X point is converted into an O point that finally becomes the magnetic axis of the spheromak. In this latter phase of reconnection, the plasma is heated very strongly. Studies have also been done on the effect of the difference in phase and time scales for the reversal and Iz banks for the purpose of optimization. The effect of radiation from carbon and oxygen is examined and found to have very little effect on the proposed formation scheme. The results are also relatively insensitive to changes in the anomalous electron thermal conduction models used. [ABSTRACT FROM AUTHOR]