Magnetized hohlraum of megagauss-field generated by capacitor-coil target at the ShenGuang-II laser facility

In previous studies, the pulsed strong magnetic fields generated by the laser-driven coils (LDCs) were usually overestimated. One of the reasons is that the self-generated magnetic field and the coil-induced magnetic field exhibit different power-law decay behaviors with respect to probe distance. We design an insulated coil target to measure the net coil-produced magnetic field, and to accurately infer the magnetic field inside a magnetized hohlraum. A magnetic field is generated by laser irradiation on a capacitor-coil target featuring an X-ray maze structure. The gold hohlraum inside the coil is slitted to eliminate the diamagnetic current and enable the external magnetic field to penetrate the gold hohlraum. To delay the closure of the slit, an X-ray maze is designed between the two capacitor plates. In this work, a pulsed magnetic field with a peak strength over 500 T is generated in the magnetized hohlraum using 1053 nm lasers with pulse length of 2 ns and energy of above 1.6 kJ. An energy conversion efficiency of ~8% from laser energy to magnetic field energy was achieved. This work provides technical support for magnetized high-energy-density physics (HEDP) research.