Spectroscopic Investigation of the Particle Density and Motion in an Imploding z‐Pinch Plasma

Experimental investigations of the ion density and flow as a function of time and space in z‐pinch plasmas are of key importance for improving the understanding of z‐pinch dynamics. For such studies, measurements of emission‐line shapes can be highly useful.In the present experiment line emission of oxygen ions is used to investigate the ion density and motion in the imploding plasma in a 0.6‐μs, 220‐kA z‐pinch experiment. For the time period studied here (220 – 85 ns before the stagnation on‐axis), the plasma properties have been extensively characterized previously, employing various spectroscopic methods to determine the time‐dependent radial distributions of the ion velocities, the magnetic field, the charge‐state composition, the electron temperature, and the particle densities. In particular, the electron density was determined from the absolute intensities of spectral lines, from the ionization times in the plasma, and from momentum‐balance considerations, based on the previously measured time‐depe...