The Simulation Of Forming Process Of Z-Pinch Driven Dynamic Hohlraum Based On The Program Multi2D-Z

Abstract

The radiation hydrodynamic code MULTI-2D has been modified to develop as a radiation magnetohydrodynamic code MULTI2D-Z by adding the programm module of evolution equation of magnetic field, and self-consistently considering the Lorentz force in the module of motion equation and the Ohmic heating in the module of energy equation. The newly developed module for magnetic field was validated to be reliable. The module is used to study the magneic field diffusion process, and it is found that the diffusion is weakened duo to the increasing plasma temperature and density and the fluid convection, in which there is minus grads of velocity in radial direction. The new code is used to simulate the forming process of dynamic hohlraum driven by tungsten wire-array Z-pinch at 8MA current level. The simulated X-ray power $(\sim 30$ TW) and energy $(\sim 300$ kJ), radiation temperature in foam $(\sim 120$ eV), and the implosion trajectory of wire-array agree well with the measured data in PTS facility. Calculated results reveal that the magnetic field is mainly distributed in the outside tungsten plasma during the hohlraum formation. The foam is expanding due to the radiation heating from the shock wave created by collision of wire-array plamsa and the foam. The thermal radiation wave, which is characterized by radiation temperature, spreads towards center axis faster than the plasma temperature. When the thermal radiation wave spreads to the center axis, the radiation temperature becomes comparatively uniform, and almost equates to the plasma temperature besides at the place of the shock wave. These results help the people to better understand the magnetic field diffusion and convection in Z-pinch, as well as the formation mechanism of dynamic hohlraum driven by wire-array Zpinch. It is also indicated that the developed code MULTI2DZ can be considered as a new tool for simualtions of Z-pinch and its applications.