Achieving efficient implosion for double-shell targets driven by Z-pinch dynamic hohlraum

Double-shell targets offer significant advantages in ignition margins and energy gain. We conducted theoretical studies and radiation hydrodynamic simulations to achieve efficient implosion of the double-shell targets driven by Z-pinch dynamic hohlraum (ZPDH). Theoretical models incorporating the ablator ablation, target implosion, and shell collisions are developed. The final implosion velocity can be theoretically predicted based on the given target and radiation drive parameters. The theoretical predictions exhibit a good agreement with the results from radiation hydrodynamic simulations, with deviations within 10%. Then, an optimal target structure using the random walk algorithm is designed. It is found that a target with a 3 mm radius can be ignited and yields energy of 165 MJ under a 285.6 eV radiation-driven source produced by ZPDH with a 50 MA load current. These findings provide valuable insights for designing double- or multi-shell targets in inertial confinement fusion.