Hohlraum energetics and implosion symmetry with elliptical phase plates using a multi-cone beam geometry on OMEGA
Hohlraum energetics and implosion symmetry with elliptical phase plates using a multi-cone beam geometry on OMEGA
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DOI：
10.1088/1742-6596/112/2/022077
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发表时间：
2008-05
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通讯作者：
S. Regan;T. Sangster;D. Meyerhofer;W. Seka;R. Epstein;S. Loucks;R. Mccrory;C. Stoeckl;V. Glebov;O. Jones;D. Callahan;P. Amendt;N. Meezan;L. Suter;M. Rosen;O. Landen;E. Dewald;S. Glenzer;C. Sorce;S. Dixit;R. Turner;B. MacGowan
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文献类型：
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作者：
S. Regan;T. Sangster;D. Meyerhofer;W. Seka;R. Epstein;S. Loucks;R. Mccrory;C. Stoeckl;V. Glebov;O. Jones;D. Callahan;P. Amendt;N. Meezan;L. Suter;M. Rosen;O. Landen;E. Dewald;S. Glenzer;C. Sorce;S. Dixit;R. Turner;B. MacGowan
在 OMEGA 激光系统上进行了黑腔能量学和内爆对称实验，使用排列成三个锥体并用椭圆相位板平滑的激光束。使用 ~7-kJ 整形激光脉冲 (PS26) 用 20 束光束照射充气半射束的相位板，峰值辐射温度 (Tr) 增加了 17 eV，相当于峰值 X 射线通量增加了 44%。耦合的改进与受激拉曼散射 (SRS) 和受激布里渊散射 (SBS) 所产生的视锥相关损耗的减少相关。相位板通过控制目标激光强度包络和散斑模态功率谱来减少 SRS 和 SBS。通过改变真空和充气的薄壁 (3μm) Au 空腔的长度和光束指向，使用约 14 kJ PS26 用 40 束光束照射，进行内爆对称扫描。沿掺 Ar、D2 填充、塑料壳内爆自发射的径向和轴向视图拍摄的门控 X 射线 (hv > 3 keV) 图像量化了间接驱动内爆对称性。在具有相同光束指向的真空和充气黑腔之间观察到对称性的变化。对于充满气体的黑腔，胶囊两极相对于腰部的 X 射线驱动比率增加。黑腔等离子体中痕量的高 Z 掺杂剂（即 Ne、Kr）会降低硬 X 射线产生（hv > 20 keV）和 SRS 的水平，而峰值 Tr 增加约 5 eV。
Hohlraum energetics and implosion-symmetry experiments were conducted on the OMEGA Laser System using laser beams arranged in three cones and smoothed with elliptical phase plates. The peak radiation temperature (Tr) increased by 17 eV, with phase plates for gas-filled halfraums irradiated with 20 beams using a ~7-kJ shaped laser pulse (PS26), corresponding to a 44% increase in the peak x-ray flux. The improved coupling correlates with reduced, cone-dependent losses from stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS). Phase plates reduce SRS and SBS by controlling the on-target laser-intensity envelope and the speckle modal power spectrum. An implosion symmetry scan was performed by varying the length and beam pointing of vacuum and gas-filled, thin-walled (3-μm) Au hohlraums irradiated with 40 beams using a ~14-kJ PS26. Gated-x-ray (hv > 3 keV) images taken along radial and axial views of the self-emission from Ar-doped, D2-filled, plastic-shell implosions quantified the indirect-drive-implosion symmetry. A shift in symmetry was observed between vacuum and gas-filled hohlraums having identical beam pointing. The ratio of x-ray drive at the poles of the capsule relative to the waist increased for the gas-filled hohlraum. Levels of hard-x-ray production (hv > 20 keV) and SRS were reduced with trace amounts of high-Z dopants (i.e., Ne, Kr) in the hohlraum plasma, while the peak Tr increased ~5 eV.