431 / 2019-03-01 16:08:46

The hot-spot shape in the laser driven implosions diagnosed by a spatial flat response KB X-ray microscope

Implosion hot spot,KB X-ray microscope,Spatial flat response

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The 2D hot spot X-ray emission image diagnostics, including the shape and the fine structure, are very important in the inertial confinement fusion (ICF) implosions. Some advanced X-ray imaging systems with high spatial resolution and energy selection are required. The systems with a multi-channels KB microscope and a gated X-ray detector have been developed on NIF and OMEGA. In Laser Fusion Research Center, an 8-channel KB microscope with the periodic multilayer mirrors was commissioned for some time. Due to the small grazing angle bandwidth, the reflectivity varied rapidly with the incident angle. The reflectivity flatness in the field-of-view (FOV) was poor. The measured image would be modulated with the spatial reflectivity response. Recently, a new 4-channel KB microscope with a spatial flat response was developed for the implosion hot spot shape diagnostics. The single Pt layer mirrors were adopted. A passing energy band of 5.7-7.1keV was obtained by the K-edge of a Fe filter. The FOV range was larger than 1mm. The variation of the reflectivity was less than 10% in a FOV range of 400μm and less than 20% in a range of 800μm. The spatial resolution was about 5μm, and the designed magnification was 21. The covered solid angle was higher than 10-7 sr. The polar asymmetry of the hot spot X-ray emission was diagnosed in an equatorial view.