Critique of fluid model of the microsecond plasma opening switch

Summary form only given. We have performed several single fluid two-dimensional calculations of the evolution of a microsecond opening switch plasma (POS) driven by the rising current from a Marx generator. Although the calculations provide reasonable estimates of the bulk plasma motion and conduction time measured in experiments, the more detailed results of interferometric and spectroscopic measurements as well as physical considerations suggest significant defects in the fluid picture. In particular, these measurements indicate a plasma at the end of the conduction phase that is substantially cooler than indicated by calculations, especially for a simple gamma-law gas, and even for a plasma where the energy investment in ionization and radiation is taken into account. In the former case calculated plasma temperature reach several kilovolts, in the latter case about 200 eV in the densest parts of the compressed plasma shell to about 1 keV where the densities are about a fifth of the maximum. Transport effects not normally included in single fluid codes, though not insignificant, are estimated to be insufficient to cool the electron component of the plasma to the several tens of eV inferred from spectroscopy.