Passive high-speed imaging of ion acoustic turbulence in a hollow cathode
A passive, non-invasive plasma diagnostic is developed and validated to estimate the dispersion of electric propulsion plasmas. This new technique uses a Silicon photomultiplier (SiPM) to measure fluctuations in light intensity to estimate the dispersion of the plasma. Experimental validation of the technique was conducted on a hollow cathode. Ion acoustic waves, which are responsible for the anomalous resistivity of the cathode plume, were measured using both ion saturation probes and the SiPM technique. The results from the SiPM were compared to measurements from ion saturation probes. While the raw data and power spectra acquired with the SiPM were different, the estimated dispersion and phase velocity are within uncertainty of each other and within uncertainty of similar measurements found in the literature.
