Measuring CH-Au interface in gas-filled hohlraum using Thomson scattering on SG-III prototype

An experiment was conducted on the SG-III prototype laser facility to measure the plasma conditions in pentane-gas-filled gold hohlraum using Thomson scattering. The time-resolved plasma conditions are measured 400um off the hohlraum wall. In the measured ion feature, the transition from scattering from CH to scattering from Au is clearly resolved. Plasma parameters are obtained by fitting the ion feature with a theoretical form factor, with electron density given by radiation-hydrodynamic simulation (LARED code). A discrepancy is observed in flow velocity and electron temperature between experiment and 2D-simulation, indicating that the impact of the probe beam on the gold-bubble and 3D-effects are not negligible. A post-simulation was done to evaluate the influence of the probe beam on the plasma conditions, and the result shows, when considering probe-beam heating, (1) the CH/Au interface moves much faster, (2) the electron density inside the gold bubble decreases significantly, and (3) a density increase occurred at the CH/Au interface.