Numerical study of the propagation of ionization processes in an oxygen Z-pinch plasma

The dynamics of the ionization processes in an oxygen Z-pinch plasma has been numerically studied. Ionization balance equations incorporated in single-fluid magnetohydrodynamics (MHD) equations were solved. The focus was on the imploding phase before a shock wave was fully developed. It was shown that the propagation speed of an ionization stage is larger than the fluid speed. For example, the propagation speed of O III ionization stage is faster than the fluid speed at the position of the peak density of O III particles. The larger propagation speeds of ionization stages than the fluid speed result from the propagation of Joule heating power. (C) 1997 American Institute of Physics.