Optical tracking of Low-Z Impurities in a Stabilized Z Pinch through EUV-VIS Emission

Measurement of impurity ion parameters (n_e, n_i, v_i, B, etc.) via optical emission is an easily-accessed method of inferring the plasma conditions in a high-density, high-temperature deuterium plasma. Previous optical diagnostics on the FuZE shear-flow-stabilized Z pinch included high-resolution Ion Doppler Spectroscopy of C III/C V lines (227 & 229 nm) in conjunction with a Hadland 12-frame ICCD fast framing camera in the 350-900 nm region. These diagnostics provide high spectral resolution and nanosecond time resolution at the cost of limited understanding of the entire snowplow and quiescent period of pinch formation in FuZE. To rectify this limitation, two additional diagnostics will be fielded on FuZE-Q to track impurity movement across a long timescale and a wide spectral range. A vacuum EUV spectrometer with multichannel gating will be able to collect a sequence of spectra in the pinch formation region from excited-state C V and O VII emission in the 9-19 nm range as well as C VI and O VIII ground-state transitions in the 1.5-5 nm range. This will complement the current spectroscopic measurements of C V in the UV range, which can be compared against theoretical spectra. In addition, a fast framing Shimadzu camera, capable of 128 frames at 100 ns each, will be used to track carbon and oxygen impurity motion. A selection of narrow bandpass filters will provide the ability to select individual impurity emission lines (C II, C III, C V, O III, D-beta, etc.) instead of viewing the entire 200-900 nm emission profile. Initial spectra and images are presented.