In indirect-drive inertial confinement fusion (ICF), the radiation drive intensity of the hohlraum is related to the shock velocity and implosion velocity of the capsule. The radiation drive symmetry on the capsule is the vital parameter for the hotspot symmetry. A new method is proposed to simultaneously determine the intensity and P2 asymmetry of the drive flux on the capsule by measuring the re-emitted X-ray radiation flux along two orthogonal directions. The demonstration experiments were conducted on the Shenguang-100kJ laser facility. The interaction between the hohlraum and the imploded capsule can be decoupled by employing a high-Z substitute capsule. The effects of opacity and EOS on the measurement of the P2 asymmetry are given based on the self-similarity theory. The evolutions of the radiation drive temperature and P2 asymmetry are obtained in the experiment. The temporal trend of the symmetry is consistent between the experiment and the integrated simulation (LARED-JC). However, the experimental symmetry differs from the simulation results from the middle of the main pulse. This might be caused by the inverse bremsstrahlung absorption or the crossed-beam energy transfer (CBET) process. This measurement method can provide both radiation drive intensity and P2 asymmetry for different hohlraums in experiments, which is beneficial for optimizing the innovative hohlraum designs.
 

P2 asymmetry,radiation drive flux,re-emitted flux,experiments,diagnostics