Bifurcation in viscoresistive MHD: the hartmann number and the reversed field pinch
A scaling approach to the simplest viscoresistive MHD model reveals that the Prandtl number acts only through the inertia term. When this term is negligible the dynamics is ruled by the Hartmann number H only. This occurs for the reversed field pinch dynamics as seen by numerical simulation of the model. When H is large the system is in a multiple helicity state. In the vicinity of H = 2500 the system displays temporal intermittency with laminar phases of quasi-single-helicity (SH) type. For lower H's two basins of SH are shown to coexist. SH regimes are of interest because of their nonchaotic magnetic field.
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Consorzio RFX, Corso Stati Uniti 4, 35127 Padova, Italy and Consiglio Nazionale delle Ricerche, Italy.
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