High-resolution spectroscopic X-ray diagnostics for studying the ion-kinetic energies at the stagnation of a Z-pinch plasma

Summary form only given. Spectroscopic systems with toroidally bent crystals, giving resolving power of 7000 and time-gated (1 ns) spatially-imaged spectra with 0.1 mm resolution, are used to obtain the kinetic energies of [H] ions as a function of time throughout the stagnation phase in a neon-puff, 350 kA Z-pinch experiment. The spectrographs were so designed to allow for Rocking-Curve-limited spectral resolutions, verified by double-grating measurements. Optically thin lines (mainly satellites) are utilized in order to obtain the Doppler contribution to the line profiles. The data show that the mean ion kinetic energies drop drown to the electron thermal energy at the end of the radiation phase of the plasma. The data also yield the electron density from the satellite-intensity ratios, and the total ion densities from line-shape measurements and analysis of the opacity effects. This allows for the investigation of the ion-energy conversion at stagnation and comparisons to the radiated energy, using collisional-radiative and radiation-transport calculations. The variations observed in the plasma structure and in the ion velocities along the pinch column allows for studying the relation between the ion-kinetic-energy history and the ionization processes in the plasma. In addition, the shapes of the resonance and intercombination lines of He-like ions are used to obtain the properties of the colder parts of the plasma. The energy balance in the plasma and inferences of temperature and density gradients will be discussed.