Improvements to the Ion Doppler Spectrometer Diagnostic on the HIT-SI Experiments

Abstract

An Ion Doppler Spectrometer diagnostic system has been constructed to measure impurity ion temperature and velocity on the HIT-SI and HIT-SI3 spheromak devices with improved spatiotemporal resolution and lower error. Hardware and software improvements have resulted in a record 6.9 µs temporal and ≤ 2.8 cm spatial resolution in the midplane of the devices. With these, C III and O II flow, displacement, and temperature profiles can be simultaneously observed. In other words, we describe analysis and hardware improvements made to a spectrometer which significantly expand the measurement possibilities, for plasma physics applications. This paper has been submitted to the journal, Review of Scientific Instruments.