Measuring the Ion Temperature of a Plasma Jet Undergoing Instability-Driven Heating

Outlined are arrangements to measure the ion temperature of a plasma jet undergoing instabilities and an examination of experiment findings. The jet, formed by puffing a controlled amount of Nitrogen or Argon gas into Embry-Riddle's cylindrical vacuum chamber and then ionizing it via high-voltage electronically switched capacitor banks, is regulated to undergo three distinct instability regimes, stable, current-driven, and pinched (or detached), dependent on the voltage of an externally applied bias field and initial conditions. Ion temperature measurements of plasma are inferred through analysis of the Doppler-broadening observed spectroscopically at relevant wavelengths. To improve measurements, this arrangement implements a unique assemblage of 54 fiber-optic cables organized into a systematic two-dimensional array that broadens the area of observation and refines fidelity to distinguish collections at surveyed locations and then reconfigures the array to a one-dimensional output for simultaneous spectroscopy. This effort aims to support future research of plasma preheating for fusion projects and investigations of solar jets, to overall enhance our understanding of ion heating due to instabilities.