Crossed-beam energy transfer in direct-drive implosions
Crossed-beam energy transfer in direct-drive implosions
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DOI：
10.1063/1.4718594
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发表时间：
2011-10
影响因子：
2.2
通讯作者：
I. Igumenshchev;W. Seka;D. Edgell;D. T. Michel;D. Froula;V. Goncharov;R. Craxton;L. Divol;R. Ep
中科院分区：
文献类型：
--
作者：
I. Igumenshchev;W. Seka;D. Edgell;D. T. Michel;D. Froula;V. Goncharov;R. Craxton;L. Divol;R. Ep
OMEGA 激光器的直接驱动内爆实验 [T. R. Boehly 等人，选项。交流。 133, 495 (1997)]显示了散射（非吸收）光水平的模拟与测量的光水平之间的差异，表明存在一种使激光耦合效率降低 10%-20% 的机制。这似乎是由于交叉束能量转移 (CBET) 涉及电磁种子、低增益受激布里渊散射。 CBET 将能量从入射光束的中心部分散射到出射光，从而降低激光吸收和内爆的流体动力效率。包括 CBET 在内的一维流体动力学模拟与 OMEGA 上内爆实验中的所有观测结果均表现出良好的一致性。考虑了三种减轻 CBET 和改善激光耦合的策略：使用窄光束、多色激光器和高 Z 烧蚀器。使用窄光束在 OMEGA 上进行的实验表明，内爆性能有所改善。
Direct-drive-implosion experiments on the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] have showed discrepancies between simulations of the scattered (non-absorbed) light levels and measured ones that indicate the presence of a mechanism that reduces laser coupling efficiency by 10%-20%. This appears to be due to crossed-beam energy transfer (CBET) that involves electromagnetic-seeded, low-gain stimulated Brillouin scattering. CBET scatters energy from the central portion of the incoming light beam to outgoing light, reducing the laser absorption and hydrodynamic efficiency of implosions. One-dimensional hydrodynamic simulations including CBET show good agreement with all observables in implosion experiments on OMEGA. Three strategies to mitigate CBET and improve laser coupling are considered: the use of narrow beams, multicolor lasers, and higher-Z ablators. Experiments on OMEGA using narrow beams have demonstrated improvements in implosion performance.