Self-similar dynamics of fiber initiated high-density z-pinch

The general interest to the fiber-initiated high-density Z pinches after the first successful experiments stimulated active studies of structure, dynamics and stability of dense z pinches. The most intriguing feature of these experiments is the observed remarkable stability of the z pinch plasma. To study the stability at least 1D fluid model is needed. The pinches are stable and plasma slowly expands as current increases. The velocity of the plasma expansion increase rapidly beginning from the instant when dI/dt=0, and pinch became unstable. As these pinches appear to be stable for many Alfven transit times τa, they represent essentially subsonic plasma flows. The first step to study the dynamics of dense pinches is the adequate description of the unperturbed plasma motions. The required fluid model of the pinch plasma should take into account dissipations because the time variation of the pinch flow is comparable to the Ohmic heating time. Hence, we use the full system of one-fluid two-temperature MHD, neglecting inertia and viscosity, but retain the other dissipative terms that is the terms describing the transverse heat conductivity, the thermogalvanomagnetic effects, called Nernst and Ettingshausen effects, and electron-ion temperature relaxation, all of them being of the same order. (author) 5 refs., 2 figs