Post-implosion anomalous transport associated with the lower-hybrid drift instability

The immediate post-implosion phase of the ZT-1 toroidal pinch experiment is characterized by an anomalously high resistivity so that the average density and magnetic field profiles distort from an MHD-stable configuration to a regime where plasma confinement is lost, probably through an m = 1 kink instability. Moreover, linear theta-pinch experiments during the late stages of imposition often exhibit considerably more diffuse magnetic field profiles than predicted by existing fluid-numerical studies. The experimental results strongly suggest that substantial anomalous resistivity persists even in the low-drift-velocity regime Vsub(E) approximately < vsub(i). An extensive survey of microinstabilities for parameters appropriate to the post-implosion phase of high-density pinches has identified the lower-hybrid-drift instability as the most likely candidate for producing significant anomalous transport. The linear stability behavior and anomalous transport properties associated with this instability are examined assuming flute-like perturbations with k tilde . B tilde 0 = 0. (U.K.)