Anomalous stability of the cryogenic z-pinch

The physics of the z-pinch phenomenon is examined with emphasis on the anomalous stability of the plasma column (time of evolution of the constriction instability is of the order of 1 ns), for which no hypotheses have been proposed to date. Here, it is suggested that the plasma column is strongly nonequilibrium, with hot electrons coexisting with cold ions, even though the medium density is close to that of a solid. Estimates are presented to support the possibility of such nonequilibrium and anomalous stability with respect to MHD instabilities.