A novel investigation of the ion temperature and hydromotion of stagnating z-pinch plasma using Stark-broadened line shapes*

In imploding plasmas, there is a severe lack of detailed experimental data on the thermalization processes that govern the ion temperature at stagnation, and on the energy delivered to radiation. Here, we report on a novel spectroscopic system, used to determine the temporally-resolved ion temperature and total ion kinetic energy, as well as the electron temperature and density. We use a neon Z-pinch, imploding under a 500-kA, 500-ns current pulse, and observe a hot-and-dense plasma core stagnating on axis for $\sim$ 10 ns. A two-spectrometer diagnostic system is employed, simultaneously recording two groups of optically-thin lines: He-like satellites to Ly$_\alpha$ and high-\textit{n} H-like Ly$_\delta$ and Ly$_\epsilon$ lines, with ultra-high resolutions in spectrum, time and space. The ion temperature is obtained, as a function of time, by analyzing the ion-correlation-affected shapes of the Stark-broadened high-\textit{n} lines. The total Doppler width yielded the total ion kinetic energy. The ion temperature is found to be substantially lower than the hydrodynamic-motion energy, the dissipation time of which is determined as well.