Stimulated Raman scattering mechanisms and scaling behavior in planar direct-drive experiments at the National Ignition Facility
Stimulated Raman scattering mechanisms and scaling behavior in planar direct-drive experiments at the National Ignition Facility
复制标题
DOI：
10.1063/1.5139226
复制
发表时间：
2020-04
影响因子：
2.2
通讯作者：
M. Rosenberg;A. Solodov;W. Seka;R. Follett;J. Myatt;A. Maximov;C. Ren;S. Cao;P. Michel;M. Hohenberger;J. Palastro;C. Goyon;T. Chapman;J. Ralph;J. Moody;R. Scott;K. Glize;S. Regan
中科院分区：
文献类型：
--
作者：
M. Rosenberg;A. Solodov;W. Seka;R. Follett;J. Myatt;A. Maximov;C. Ren;S. Cao;P. Michel;M. Hohenberger;J. Palastro;C. Goyon;T. Chapman;J. Ralph;J. Moody;R. Scott;K. Glize;S. Regan
受激拉曼散射(SRS)在国家点火装置的平面几何实验中，在与惯性约束聚变点火尺度直驱靶电晕相关的条件下得到了全面的研究。在测量的电子温度为4~5keV，模拟密度标度L n为400~700μm，四分之一临界密度为1.5×10~(15)W/cm~2的条件下，这些实验确定了受激喇曼散射阈值和不同束流几何形状下的受激喇曼散射标度行为。已经确定了几种受激拉曼散射机制，包括四分之一临界密度附近的饱和绝对受激拉曼散射和附加受激拉曼散射，包括较低密度下的近后向散射或侧向散射。观察到在临界密度∼为0.15到0.21时随时间变化的受激喇曼散射与热电子特征信号以及不同实验中这些特征信号的大小之间的关联。需要进一步的建模工作，以确定产生热电子的密度区域，并将指导直接驱动点火设计的SRS和热电子预热缓解战略。
Stimulated Raman scattering (SRS) has been explored comprehensively in planar-geometry experiments at the National Ignition Facility in conditions relevant to the corona of inertial confinement fusion ignition-scale direct-drive targets. These experiments at measured electron temperatures of 4 to 5 keV simulated density scale lengths L n of 400 to 700 μm, and laser intensities at the quarter-critical density of up to 1.5 × 1015 W/cm2 have determined SRS thresholds and the scaling behavior of SRS for various beam geometries. Several SRS mechanisms, including saturated absolute SRS near the quarter-critical density and additional SRS, including near-backscatter or sidescatter at lower densities, have been identified. Correlation of time-dependent SRS at densities ∼0.15 to 0.21 of the critical density with hot-electron signatures as well as the magnitudes of these signatures across different experiments, is observed. Further modeling work is needed to definitively identify the density region in which hot electrons are generated and will guide SRS and hot-electron preheat mitigation strategies for direct-drive-ignition designs.