Measurement of XeI and XeII velocity in the near exit plane of a low-power Hall effect thruster by light induced fluorescence spectroscopy

TL;DR

This study employs light induced fluorescence spectroscopy to measure the velocity components of XeI and XeII ions near the exit of a low-power Hall thruster, revealing ion velocity distributions and their origins within the acceleration channel.

Contribution

It introduces a non-intrusive optical method to measure ion velocities in a Hall thruster, providing detailed velocity profiles of XeI and XeII ions.

Findings

XeI velocity matches thermal velocity expectations.

Two dominant ion velocities are observed, linked to ion creation zones.

Spatial resolution limitations are identified due to setup constraints.

Abstract

Near exit plane non-resonant light induced fluorescence spectroscopy is performed in a Hall effect low-power Xenon thruster at discharge voltage of 250V and anode flow rate of 0.7mg/sec. Measurement of the axial and radial velocity components are performed, exciting the 6s[3/2]_2-->6p[3/2]_2 transition at 823.16nm in XeI and the 5d[4]_(7/2)-->6p[3]_(5/2) transition at 834.724nm in XeII. No significant deviation from the thermal velocity is observed for XeI. Two most probable ion velocities are registered at a given position with respect to the thruster axis, which are mainly attributed to different areas of creation of ions inside the acceleration channel. The spatial resolution of the set-up is limited by the laser beam size (radius of the order of 0.5mm) and the fluorescence collection optics, which have a view spot diameter of 8mm.