Investigation on the main characteristics of dynamic hohlraum formation at the Julong-1 facility

Z-pinch dynamic hohlraum experiments have been carried out at the Julong-1 facility by imploding a nested tungsten wire array, which is configured with 20/10 mm diameter and 168/84 wires of 6.0 μm in diameter for the outer/inner array, onto a 10 mg/cc C15H20O6 foam converter with a radius of 2.3 mm. Detailed processes of shock formation, propagation, and radiation transfer of dynamic hohlraum were experimentally observed using an on-axis x-ray imaging system with simultaneous dual spectral channels. When the wire array plasma impacts onto the foam converter, thermalization of kinetic energy at the interaction zone generates a shock that propagates inward. The energy dissipated by imploding plasmas increases gradually, resulting in the strengthening of shock wave and finally the formation of the main radiating shock. During the propagating period of radiating shock, thermal radiation gradually transfers into the inner region, and a uniform hohlraum is produced when the main shock arrives at a radius of 0.8 mm in the experiments at the Julong-1 facility. The experimental results first describe the physics of about 100 eV hohlraum formations and may extend our understanding of Z-pinch dynamic hohlraums for future inertial confinement fusion applications.