Fluid-numerical studies of high-density theta-pinch implosion including classical and anomalous transport processes

For parameters appropriate to high-density pinch experiments (ne ⪆ 1014 cm−3) it is shown that both classical transport processes and anomalous transport processes can play an important role during the implosion. The fluid-numerical model of Liewer and Krall has been modified and extended to include (in addition to turbulent transport) the effects of classical transport (e.g. frictional force, thermal force, heat conduction, heat convection, resistive heating and thermalization), as well as the effects of ionization, neutral-particle diffusion and charge exchange. Numerical studies of the early and intermediate stages of implosion are presented for parameters appropriate to Scylla 1-B and Scyllac. It is found that the relative importance of the various transport processes depends in detail on radial location, initial ionization level, bias field, etc. As a general remark, however, anomalous transport processes tend to dominate in the sheath region and behind the piston (where the current and temperature are relatively high), whereas classical transport processes are important in front of the piston (where the density is high and the temperature is relatively low). Moreover, for sufficiently large initial neutral density, the effects of charge exchange, neutral-particle diffusion, and ionization, are found to be significant during the implosion.