Magnetic Field Simulation and Mapping Based on Zeeman-split Laser-inducedFluorescence Spectra of Xenon in the Discharge Channel of a 5-6 kW Co-Axial Stationary-Plasma Hall Thrusters.

Hall Thruster;Field Mapping from Laser-induced Fluorescence Spectra of Neutral Xenon in the Near Infra-red Using a Diode-laser;Effect of Hall Current on Magnetic Field;Zeeman Splitting of Fine and Hyperfine Structure;Field Simulation Using Magnostatic Solver;Component of Neutrals"Temperature Along the Axial Direction;Aerospace Engineering;Engineering;Aerospace Engineering

Ngom, Bailo BahSmith, Timothy B. ;

University of Michigan

关键词: Hall Thruster;    Field Mapping from Laser-induced Fluorescence Spectra of Neutral Xenon in the Near Infra-red Using a Diode-laser;    Effect of Hall Current on Magnetic Field;    Zeeman Splitting of Fine and Hyperfine Structure;    Field Simulation Using Magnostatic Solver;    Component of Neutrals";    Temperature Along the Axial Direction;    Aerospace Engineering;    Engineering;    Aerospace Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/64615/bbahn_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

We studied the effect of the Hall current’s induced magnetic field on the vacuumfield of coaxial Hall thrusters based on MagNet 6 simulation of a 5 kW thruster (P5)and laser-induced fluorescence spectra taken at the exit plane of a 6 kW thruster(H6).MagNet 6 simulations were performed at power settings of 1.6 kW and 3 kW—each with a proper set coil currents and Hall current density distributions. The Hallcurrent—simulated using a rectangular array of current-carrying coils —induced asignificant reduction of the field strength . The radial component of the field strengthshifted towards the anode by as much as 10 mm and its gradient lost its mononoticityas the Hall current’s magnitude increased. Additionally, an increase in the concavityof streamlines along the axial direction was noted in the channel.MagNet simulations were compared to non-intrusive radial field strength measurementsat the exit of the 6 kW thruster from Zeeman-split laser-induced fluorescencespectra of neutral xenon (6S′ [1/2] → 6P′ [3/2] about 834.912 nm-vacuum) by fittingmeasured spectra with Lorentz and Doppler-broadened Zeeman-split fluorescencelineshapes.Spectra were modeled using a linear Zeeman theory of fine structure splitting ofisotopes with zero nuclear spin and a non-linear Zeman model of the splitting ofhyperfine lineshape components of isotopes with non-zero nuclear spin. The resultingisotopes’ line spectra were shifted, scaled (by natural abundance) and Lorentz- andDoppler-broadened (Voigt-profile) to yield neutrals’ absorption spectrum.A commercial non-linear least-squares solver was then used to compute radialcomponents of the magnetic field strength and axial kinetic temperatures that minimizethe fitting error between experimental and simulated spectra. The solver wasapplied to laser-induced fluorescence spectra measured at the exit plane of a 6 kWHall thruster (H6). The resulting magnetic field strength calculations revealed, as inthe MagNet 6 simulation study of the P5, that the plasma induces a reduction of theradial component of the field strength. Axial kinetic temperatures of neutral xenonparticles remained fairly constant near the channel’s centerline; closer to the innerwall, however, the temperature was found to be twice larger.