Optical Emission Spectroscopy of Plasma Formation in a Xenon Theta Pinch

Analyses of xenon spectral emission data in the IR range primarily from Xe I transitions and estimations of electron temperature are performed on a theta pinch test article. Estimations are based on a collisional-radiative model originally written for Hall-effect thrusters by Karabadzhak et al. which takes into account metastable species in the 1s excited state of xenon. Tests performed on a pulsed xenon plasma at an energy of 80 joules, neutral back-fill pressures of 10ˉ² to 10ˉ¹ Torr, and discharge frequency of 460 kHz yield electron temperatures of 6.5 to 11.3 eV for cumulative spectra in the first 20 µs. Spectra acquired in the UV range verify the presence of 2nd order diffraction from Xe II transitions. Low single-to-noise ratios for optical gate widths of 250 nanoseconds produce substantial fluctuation in intensities and thus estimation errors, while not quantified here, are assumed high