In research of Inertial Confinement Fusion, the middle and high Z ablator enters into the hotspot which will cause the hotspot mix due to the hydrodynamics instability developed during the implosion compression stage. An enhanced Bremsstrahlung radiation which results in the additional energy loss of the hotspot due to the increase in electron density will significantly reduce the implosion performance and decrease the fusion gain. The Bremsstrahlung spectrum of the hotspot is related to the electron density and temperature, especially sensitive to the quantity of the mix materials which have more outer electrons. A ross filter pairs imaging is developed to measure the hotspot Bremsstrahlung spectrum. The components of the imaging system were calibrated and the spectrum were measured absolutely. And the 2D implosion dynamics simulation with different pre-mix models are carried out to analysis and modify the integral emission spectrum of the hotspot. A regular fit method is developed to estimate the mix fraction. The varies of the mix fraction were captured ana analyzed by the imaging system for the different implosion design. The channels of the system is modified to cover the soft energy band also. The low energy channels were used to analysis the ablator emission influence and to optimize the mix emission spectrum models. A obviously emission of the interface of ablator and hotspot was measured due to the radiation shock in low energy channels in some experiments. The influence on mix measurement is estimated and more information of implosion performance is analyzed. The system is expected to add more channels and to improve the spatial resolution. And an real-time measurement design is under developing and will be test in future.

diagnistics,hotspot mix,Ross filter pairs