Kostick S, Filkins T, Rosenberg M J, Katz J, Theobald W, Lemos N, Tubman E, Sommers R, Hernandez J E, Swadling G, Ross J S, Radha P B, Grullon F, Heinmiller J M, Fornes J, Hillyard P, McCumber J, Ceurvorst L, Regan S P
Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA.
Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627-0132, USA.
Rev Sci Instrum. 2024 Sep 1;95(9). doi: 10.1063/5.0218987.
The scattered-light time-history diagnostic (SLTD) suite measures time-resolved scattered light in three wavelength bands: stimulated Brillouin scattering (350-352 nm), stimulated Raman scattering (430-760 nm), and plasma emission at half the laser frequency (695-735 nm), at 15 locations around the National Ignition Facility (NIF) target chamber. The SLTD, along with the full-aperture backscatter station (FABS), collects scattered light from direct- and indirect-drive inertial confinement fusion experiments. The SLTD calibration was revisited after a discrepancy between FABS and SLTD measurements was observed on NIF polar direct-drive [Skupsky et al., Phys. Plasmas 11, 2763 (2004)] experiments. An integrated calibration of the SLTD was performed for the first time, and individual components were also calibrated for the wavelengths of 351, 527, and 532 nm. The optical transmission of the instrument was measured to be (1.12 ± 0.04) × 10-7 and (1.96 ± 0.11) × 10-7 for the wavelengths of 351 and 532 nm, respectively. The revised calibration at 351 nm brings the SLTD measured scattered energy in agreement with the FABS measured scattered energy after additionally accounting for the degradation of an optical element in FABS. This decreased the inferred absorption by 7% for a representative experiment. However, discrepancies remain between FABS and SLTD measurements in the SRS band (532 nm).
散射光时间历程诊断（SLTD）套件在国家点火装置（NIF）靶室周围的15个位置，测量三个波长波段的时间分辨散射光：受激布里渊散射（350 - 352纳米）、受激拉曼散射（430 - 760纳米）以及激光频率一半处的等离子体发射（695 - 735纳米）。SLTD与全孔径背散射站（FABS）一起，收集直接驱动和间接驱动惯性约束聚变实验中的散射光。在NIF极向直接驱动实验[斯库普斯基等人，《物理等离子体》11, 2763 (2004)]中观察到FABS和SLTD测量值之间存在差异后，重新审视了SLTD校准。首次对SLTD进行了综合校准，还对351、527和532纳米波长的各个组件进行了校准。分别测量了该仪器在351和532纳米波长下的光传输率为(1.12 ± 0.04) × 10⁻⁷和(1.96 ± 0.11) × 10⁻⁷。在351纳米处修订后的校准，在额外考虑FABS中一个光学元件的退化后，使SLTD测量的散射能量与FABS测量的散射能量一致。对于一个代表性实验，这使推断的吸收率降低了7%。然而，在受激拉曼散射波段（532纳米），FABS和SLTD测量之间仍存在差异。
