Simultaneous High-Temporal- and High-Spectral-Resolution Measurements of Plasma Impurities

Previous spectroscopic efforts on the FuZE sheared-flow-stabilized Z Pinch have employed three systems to measure temporal, spatial, and spectral ion dynamics. The first system records high-spectral-resolution images, utilized to infer plasma parameters (n_e, T_i, v_i, B, etc.) from the C III 229.7 nm line and C V 227 nm triplet. However, these spectra are line-integrated at a single axial location and time integrated from 0.1-1.0 us. A second spectrograph records medium-resolution spectra at multiple axial locations on the FuZE chamber, but also time integrated. Finally, a fiber-coupled photodiode equipped with a fixed bandpass filter collects the emission of an ion line at a single location with high temporal fidelity but without any spectral information. With limited space for diagnostic access, these systems cannot be used to analyze the plasma at the same location simultaneously. A newly designed spectroscopic system based on a dual-exit-plane spectrograph combines all three capabilities to provide simultaneous high-temporal- and high-spectral-resolution data at multiple axial or radial locations during each shot. A small-pixel ICCD camera on one exit plane provides very high spectral resolution to extract plasma parameters as before, and a PMT array on the second exit plane provides high temporal resolution for simultaneous ion line intensity dynamics. The system is optimized for the weak emission of the C V triplet, but can be used on any spectral region in the 200-500 nm range. Initial spectra and data are presented.