Analysis of laser imploded core plasma formation by Li-like satellite lines from argon dopant

Core plasma formation in a laser-driven fusion pellet is studied by means of time-resolved X-ray spectroscopy. The fusion pellet containing a high pressure deuterium gas doped with a small amount of Ar was irradiated with high-power laser beams from Gekko XII, and the temporal evolution of spatially-averaged electron temperatures and densities was inferred from Ar K-shell emissions. In a previous paper (Y. Ochi et al., JQSRT 2000;65:393), we note that a uniform core plasma was attained only when the uniform irradiation conditions were satisfied. Based on this result, in the present study, an additional low-modal non-uniformity was intentionally imposed on the pellet to investigate its influence on the core plasma formation. Experimental results showed that Li-like satellite lines from Ar became more intense than the He-beta resonance line at the later time of implosion. Focusing on this feature, we derive plausible combinations of the electron temperatures and densities of the core plasma by evaluating atomic processes that dominate the line emissions. We suggest, in comparison with one-dimensional hydro-code simulations of the implosion, that the core plasma is quenched probably due to hydrodynamic mixing of the cold dense pusher with the hot core, which is initiated by the drive non-uniformity. (C) 2001 Elsevier Science Ltd. All rights reserved.