Relaxation of spheromak plasmas toward a minimum-energy state through global magnetic fluctuations

Globally coherent modes which are observed during formation in the S-1 Spheromak plasma are shown to be important for flux conversion and plasma relaxation toward a minimum-energy state. A significant finding is the temporal progression through the n = 5, 4, 3, 2; m = 1 mode sequence as q rises through rational fractions m/n, where n and m are defined by the functional dependence e/sup i(nphi + mtheta/) of the fluctuations on toroidal angle phi and poloidal angle theta. Resistive MHD analysis predicts the observed modes and the sequence of occurrence