Fig. 1. (a) Experimental setup, with nine laser beams injected into a cylindrical gas-filled Au hohlraum. The blue beams are 3ω heaters. The red beam is the 3ω interaction beam. The purple and lilac beams are the 4ω TS probe beam and the TS light, respectively. The green square is the TS diagnostic volume. (b) Relative timings of 3ω beams and the 4ω beam. (c) Diagram detailing the ion-acoustic wave vector probed. Here, k⃗0, k⃗s, and k⃗I are the wave vectors of the interaction beam, the SBS light, and the SBS-driven IAW, respectively.

Fig. 2. (a) Time-resolved spectrum of SBS light from the interaction beam. (b) Time-resolved spectrum of the TS light off the SBS-driven IAW in the diagnostic volume shown in Fig. 1(a). Frequency shifts of SBS light and TS light respectively relative to the interaction beam and the probe beam at (c) 0.4 ns and (d) 1.6 ns.

Fig. 3. Simulated spatial distributions of plasma parameters at 0.4 ns [(a) and (b)] and 1.6 ns [(c) and (d)]. The black dashed lines show the boundaries of heater beams with diameters of 500 μm in the R direction. The gray lines at the left of (b) and (d) are the interfaces between the Au and CH plasmas. The electron density along the red line in (b) is shown in Fig. 4. The green square is the TS diagnostic volume. Here, n_c is the critical density of the 3ω laser, n_c ≈ 9 × 10²¹ cm⁻³.

Fig. 4. Electron density profiles across the 3ω laser as marked by the red line in Fig. 3(b). The black lines are the boundaries of interaction beam. The dashed gray lines are the boundaries of the heater beam.

Fig. 5. Temporal spectra of SBS [(a) and (c)] and TS [(b) and (d)] light from calculations without [(a) and (b)] and with [(c) and (d)] ion–ion collisions.

Fig. 6. Spatial growth rates [(a) and (b)] and spatial spectra [(c) and (d)] of SBS light from the calculations without [(a) and (c)] and with [(b) and (d)] ion–ion collisions, at 1.0 ns. The growth rates are calculated at the pump light intensity at the left boundary [I₀(0)] and the plasma length across the whole computational domain. (e) SBS spectra at (red lines) the left boundary and (blue lines) the CH/Au interface from the calculations without (dashed lines) and with (solid lines) ion–ion collisions.

Fig. 7. (a) Profiles of plasma flow velocity along the ray path. The triangles and stars indicate the membrane/CH and CH/Au interfaces, respectively. (b) Spatial integral growth rates over the entire computational domain with (solid lines) and without (dashed lines) the membrane plasma.

Fig. 8. Spectra of (a) SBS and (b) TS light calculated by doubling the membrane plasma density in 0–0.7 ns.

Fig. 9. Transverse profiles of (a) laser intensity, (b) electron temperature and (c) electron density for beams with different diameters: the interaction beam with a diameter of 300 μm (red) and the heater beam with a diameter of 500 μm in the LEH plane (blue).

Fig. 10. (a) Schematic of the simulation for a cup-shaped hohlraum. (b)–(d) Distributions of electron temperature, flow velocity, and electron density, respectively, at 0.4 ns (orange lines) and 1.0 ns (dark green lines) along the transverse direction of the probe beam [on the yellow line in (a)]. n₀ here denotes the initial electron density.

Fig. 11. Spatial distributions of electron temperature (red lines) and plasma flow velocity (blue lines) along the interaction beam at (a) 0.4 ns and (b) 1.6 ns. The dashed lines show the original data from the LARED simulation, and the solid lines are the results corrected by considering the heating effect of the TS probe beam.

Fig. 12. Spatial distributions of electron density (red lines) and SBS reflectivity (blue lines) along the edge of the interaction beam near the hohlraum center. The dashed lines show the original data from the LARED simulation, and the solid lines are the results after considering the heating effects of (a) the 300 μm-diameter interaction beam at 0.4 ns and (b) the TS probe beam at 1.6 ns.

Fig. 13. (a) and (b) Temporal behaviors of SBS and TS light, respectively. Here, the black lines are experimental data. The colored lines represent three calculation cases: case A (blue) is the calculation with the original simulated plasma parameters; case B (green) is the calculation considering only the heating effect of the interaction beam; case C (red) is the calculation considering the heating effects of both the interaction beam and the TS probe beam. (c) and (d) Spectra of SBS and TS light, respectively, from calculation case C.

Fig. 14. Temporal behavior of SBS lights from different regions of the interaction beam: upper edge (blue), central region (green), lower edge (red), and whole beam (black).