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ABSTRACTEnergetic xenon ion collisions with neutral atoms play an important role in electric thruster plasma radiation at low electron temperatures. The respective emission excitation cross sections are necessary for the derivation of plasma parameters from the observed radiance. We present apparent emission excitation cross sections for near-infrared 5p 5 6p to 5p 5 6s transitions of neutral xenon impacted by singly and doubly charged xenon ions. The cross sections were measured over a laboratory energy-per-charge-number range of 100 to 900 eV, a range that covers typical Hall effect thruster discharge voltages. The cross sections are derived from ion beam luminescence spectra produced at single-collision conditions and at pressures for which radiation trapping effects were shown to be negligible. The Xe* cross sections are significantly higher than those of Xe 2 l and increase with energy throughout the investigated range. The Xe 2 1 cross sections plateau at approximately 600 eV. The cross sections are incorporated in a collisional-radiative model. The calculations of near-infrared spectra demonstrate that the sensitivity of the model diagnostic with respect to electron temperature increases with ion energy.
SUBJECT TERMS
C.Energetic xenon Ion collisions with neutral xenon atoms play an important role in electric thruster plasma 0 radiation at low electron temperatures The respective emission excitation cross sections are necessary for the derivation of plasma parameters from the observed radiance. We present apparent emission excitation cross sections for near-infrared 5p s 6p to 5ps6s transitions of neutral xenon impacted by singly and doubly charged xenon ions. The cross sections were measured over a laboratory energy-per-charge-number range of 100 to 900 eV, a range that covers typical Hall effect thruster discharge voltages. The cross sections are derived from ion beam luminescence
Bismuth metal vapor Hall thrusters may have superior performance and economic characteristics when compared to xenon. From increased efficiency to reduced propellant and testing costs, bismuth seems to have a bright future. Of paramount importance when developing a practical bismuth device is the mechanism by which the propellant flow is controlled. This paper reports on an effort to use waste heat from the thruster to control the evaporation of a reservoir of liquid bismuth maintained within the discharge chamber. Research done thus far indicates that mass flow control can be achieved via a segmented anode configuration that serves as a thermostat to control input power into the bismuth reservoir. Thermal modeling has indicated that sufficient thermal gradients can be maintained between anode segments. Laboratory testing on xenon development thrusters validates the scheme to control reservoir temperature through discharge current sharing.
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