High-resolution measurements of Cl15+ line shifts in hot, solid-density plasmas

The shifts of the $1s3p{\phantom{\rule{0.16em}{0ex}}}^{1}{P}_{1}\ensuremath{\rightarrow}1{s}^{2}{\phantom{\rule{0.16em}{0ex}}}^{1}{S}_{0}$ He-$\ensuremath{\beta}$ transition of ${\mathrm{Cl}}^{15+}$ were measured in hot ($\ensuremath{\ge}600$ eV), dense (1--2 g/${\mathrm{cm}}^{3}$) plasmas generated by a (66--151)-J short-pulse laser beam at the Orion laser facility. The subpicosecond laser beam irradiated optically thin, KCl microdot targets buried in layers of plastic. The measured red shifts ranged from $4.8\ifmmode\pm\else\textpm\fi{}1.1$ eV for unshocked to $5.9\ifmmode\pm\else\textpm\fi{}1.2$ eV for shocked targets. These values are significantly smaller than recent predictions from a self-consistent-field ion-sphere model.