Density diagnosis based on ps-duration-pulse X-ray backlighting for fast ignition compression
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摘要: 为了给快点火集成耦合效率的计算提供关键参数，并为后期高密度压缩奠定高能背光的诊断基础，在神光-Ⅱ升级装置上利用皮秒短脉冲激光驱动产生了X射线背光源，测量了成像分辨率、光通量，获得了短脉冲背光源的辐射特性，进一步成功演示了基于这种短脉冲背光照相技术的间接驱动快点火预压缩密度诊断。实验所得图像与模拟图像结构一致，实测压缩过程中的面密度达到50 mg/cm2。实验还发现了压缩不对称引起的流体不稳定性特征，为后续实验提供了改进方向。Abstract: To provide significant parameters for fast ignition coupling efficiency and density diagnosis for higher compression, a ps-duration X-ray backlighter has been produced with ps-duration laser on Shenguang-Ⅱ updated facility. The radiation properties such as backlighting image resolution and the photons arriving at the image plate have been successfully measured. Based on the conformed conditions, density diagnosis of an indirectly-driven fast ignition target using ps-duration backlighting has been carried out. The obtained short-pulse backlighting radiography shows that the imploded shell shape agrees well with that of simulation and the areal density exceeds 50 mg/cm2. The short-pulse backlighting radiography also shows the hydrodynamic instability which might be caused by the asymmetric compression. Further investigations and attempts to improve implosion performance to a higher density are in progress.
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Key words:
- fast ignition /
- pre-compression /
- short-pulse backlighting /
- density diagnostics
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图 2 神光-II升级皮秒激光实测焦斑，10%（白线）50%（黑线）峰值强度等高线
Figure 2. Measured laser spot of ps laser at SG-II-updated facility，10%（white line） and 50%（black line）level contour of peak intensity
图 3 静态背光图像和成像分辨率
Figure 3. Statical backlight image, improved image and calculation result
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