2 research outputs found
Magnetic Field Simulation and Mapping Based on Zeeman-split Laser-induced Fluorescence Spectra of Xenon in the Discharge Channel of a 5-6 kW Co-Axial Stationary-Plasma Hall Thrusters.
We studied the effect of the Hall current’s induced magnetic field on the vacuum
field 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 Hall
current—simulated using a rectangular array of current-carrying coils —induced a
significant reduction of the field strength . The radial component of the field strength
shifted towards the anode by as much as 10 mm and its gradient lost its mononoticity
as the Hall current’s magnitude increased. Additionally, an increase in the concavity
of streamlines along the axial direction was noted in the channel.
MagNet simulations were compared to non-intrusive radial field strength measurements
at the exit of the 6 kW thruster from Zeeman-split laser-induced fluorescence
spectra of neutral xenon (6S′ [1/2] → 6P′ [3/2] about 834.912 nm-vacuum) by fitting
measured spectra with Lorentz and Doppler-broadened Zeeman-split fluorescence
lineshapes.
Spectra were modeled using a linear Zeeman theory of fine structure splitting of
isotopes with zero nuclear spin and a non-linear Zeman model of the splitting of
hyperfine lineshape components of isotopes with non-zero nuclear spin. The resulting
isotopes’ line spectra were shifted, scaled (by natural abundance) and Lorentz- and
Doppler-broadened (Voigt-profile) to yield neutrals’ absorption spectrum.
A commercial non-linear least-squares solver was then used to compute radial
components of the magnetic field strength and axial kinetic temperatures that minimize
the fitting error between experimental and simulated spectra. The solver was
applied to laser-induced fluorescence spectra measured at the exit plane of a 6 kW
Hall thruster (H6). The resulting magnetic field strength calculations revealed, as in
the MagNet 6 simulation study of the P5, that the plasma induces a reduction of the
radial component of the field strength. Axial kinetic temperatures of neutral xenon
particles remained fairly constant near the channel’s centerline; closer to the inner
wall, however, the temperature was found to be twice larger.Ph.D.Aerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/64615/1/bbahn_1.pd
Diode Laser-Induced Fluorescence of Xenon Ion Velocity Distributions
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77011/1/AIAA-2005-4406-547.pd