Diagnostic Developments for Plasma-Material Interactions on a Sheared-Flow-Stabilized Z Pinch

Applying sheared velocity flow to the Z pinch successfully mitigates MHD instabilities, enabling the concept to scale to high energy densities on the ZaP-HD device. This provides a unique platform for studying the plasma-material interactions (PMI) of a Z pinch at fusion-relevant conditions. High particle and energy flux to the electrodes leads to erosion of the plasma-facing surface, especially at the location of current attachment at the nose cone. Initial PMI experiments will study the behavior of a graphite nose cone using new diagnostics currently under development. During the discharge, impurity flux measurements will be made with spectroscopy by converting line-of-sight emission intensities using the number of ionization events per photon, known as the S/XB value. An infrared imaging system will be implemented to attain surface temperature measurements and heat flux. In addition, the study will include conventional ex-situ diagnostics such as scanning electron microscopy, profilometry, and mass-loss techniques that measure net changes resolved over an experimental campaign. A redesigned nose cone will enable quick and frequent removal of a portion of material for this analysis. The implementation of these techniques is described here.