Demonstration of Laser-Induced Fluorescence on Krypton Hall Effect Thruster

摘要

There is growing interest within the electrostatic propulsion community for the use of krypton as a propellant. It is a lower cost replacement for xenon, and is especially of interest for potentially very large solar electric transfer vehicles that may potentially strain xenon production capability. Understanding the subtleties of changing the propellant requires the development of new diagnostic capabilities that can probe thruster krypton propellant acceleration with the minimum disturbance to the overall propellant stream similar to those already developed for xenon. This study presents the application of laser- induced fluorescence as a plasma diagnostic technique for singly ionized krypton. Using the 728.98 nm 5d4D7/2-5p4Po 5/2 Kr II transition, we successfully measured ion velocities in the near-plume and within the acceleration channel of a laboratory model, low power Hall effect thruster. A preliminary comparison to previous xenon ion laser-induced fluorescence measurements of the same thruster indicate substantially narrowed fluorescence lineshapes, presumed to be due to decreases in plasma turbulence of the krypton operation compared to xenon. However, overall propellant energy deposition and effective electric fields calculated from the bulk ion velocities were remarkably similar.