Application of escape probability to line transfer in laser-produced plasmas

Summary Form only given, as follows. The escape probability method has been used to treat transfer of optically thick lines in laser-produced plasmas in plane-parallel geometry. The effect of self-absorption on the ionization balance and ion-level populations has been anticipated, and the effect on the laser gains in an exploding foil target heated by an optical laser has been calculated. Due to the large ion streaming motion in laser-produced plasmas, absorption of an emitted photon occurs only over the length in which the Doppler shift is equal to the linewidth. The escape probability calculated with the Doppler shift is larger than for a static plasma. Therefore, the ion streaming motion contributes significantly to the line transfer process in laser-produced plasmas. The method has been applied to both ablating slab and exploding foil targets under irradiation of a high-power optical laser. In both calculations the effect of absorption of the resonance lines on the level populations and gains is relatively large. However, the effect on the temperature and density is negligible because the radiative loss is small compared to the other losses, such as thermal transport and hydrodynamic expansion.<>