Improved Optical Diagnostic System for the FuZE-Q Experiment

Spectral data from non-invasive diagnostics provide a straightforward method of determining relevant plasma parameters (n_e, T_i, v_i, B, etc.). Previous Ion Doppler Spectroscopy on the ZaP and FuZE experiments utilized a radial and oblique telecentric telescope to calculate T_i and v_i through measuring the C III 229.7nm or O V 287.1nm lines. However, the system could not encompass the entire pinch plasma, and the telescopes were limited to a preset configuration which restricted the system's ability to measure arbitrary impurity emission lines. A new spectroscopic system that addresses the previous shortcomings will be employed for FuZE-Q. Simultaneous measurements of the z-pinch will increase from two to four with two sets of radial and oblique telescopes measuring in the x- and y-direction, respectively. Each telescope will view 15 chords to image the entire pinch plasma. In addition, a rail mount will allow the system to measure along the z-direction to provide 3D spectroscopic tomography of T_i and v_i. These data will be compared to solutions from 3D reconstruction algorithms. A low-cost, swappable lens design will provide access to more emission lines, thereby increasing our understanding of impurity and ionization migration. Initial spectra and plasma parameters are presented.