Laser induced fluorescence measurement of ion velocities in the plume of a Hall effect thruster

Williams, George; Smith, Timothy B.; Gulczinski, Frank S.; Beal, Brian E.; Gallimore, Alec D.; Drake, R. P.

doi:10.2514/6.1999-2424

Cited by 32 publications

(23 citation statements)

References 6 publications

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“…Although this assumption may be justified in many situations, it is not supported by previously published laser-induced fluorescence measurements taken downstream of a Hall thruster, which showed the ion temperature in the plume to remain nearly constant over a large area, whereas the electron temperature varied considerably over a comparable region. 12,13 When the ambiguity associated with the changing temperature ratio was considered, this method was determined to be of varying validity over the sampled plume region and, therefore, unsuitable for determining the electron temperature and number density profiles.…”

Section: Triple Probementioning

confidence: 99%

Plasma Properties in the Plume of a Hall Thruster Cluster

Beal

Gallimore²,

Haas

et al. 2004

Journal of Propulsion and Power

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Section: Triple Probementioning

confidence: 99%

Plasma Properties in the Plume of a Hall Thruster Cluster

Beal

Gallimore²,

Haas

et al. 2004

Journal of Propulsion and Power

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“…on the P5 Hall thruster. The measurements were based on a three-beam multiplex configuration, pioneered by Keefer [18] and expanded by Williams [19], [20], which yields simultaneous azimuthal, axial, and radial velocity components.…”

Section: Thruster Description and Operating Conditionsmentioning

confidence: 99%

Analysis of chamber simulations of long collecting probes in high-speed dense plasmas

Gilchrist

Bilén

Choinière

et al. 2002

IEEE Trans. Plasma Sci.

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Chamber tests of simulated electrodynamic tethers (EDTs) of different geometries operating in a dense high-speed plasma are described. The geometries tested and described here are cylindrical and flat-ribbon tape. By moving the probe samples relative to the plasma source it was possible to vary the density and therefore the effective width over a range of approximately 1 to 2 Debye lengths ( ) for the cylinder sample and 6 to 19 for the tape samples. Several important conclusions can be drawn from the tests. 1) The current-voltage characteristics of the cylinder behave as predicted by orbital-motion-limited (OML) current collection theory in the saturation region. 2) The tape tether had comparable current levels to a theoretical equal area OML cylinder up to an effective width of at least 11 and possibly wider. 3) Orienting the tape samples parallel or perpendicular to the plasma flow yielded different current responses (perpendicular is larger) above a bias potential that is near the estimated energy of the incoming beam ions. The observed difference was generally more pronounced at larger effective widths (higher densities). 4) It was also necessary to be above this bias potential to have a 0 5 current-voltage character appropriate for an ideal cylinder in the OML regime. It is concluded that wide ribbon-like tape tethers can be effective current collectors but that velocity effects will be a factor to consider, especially as relative width of the tape tether (with respect to ) grows.

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“…An argon-ion pumped dye laser was used in single-and multiplebeam techniques [20]. Both single-and four-beam techniques used a photovoltaic reference cell to provide a zero-velocity datum and wavelength calibration.…”

Section: Laser and Opticsmentioning

confidence: 99%

Measurement of 30-Centimeter Ion Thruster Discharge Cathode Erosion

Williams

Smith

Gallimore

2008

Journal of Propulsion and Power

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Relative erosion rates of the discharge cathode assembly of a 30-cm ion engine are measured using laser-induced fluorescence. Molybdenum and tungsten erosion products are interrogated downstream of the discharge cathode assembly during beam extraction. Erosion of the discharge cathode assembly is characterized for both keepered and unkeepered configurations. The erosion increases with both discharge current and voltage, and spatially resolved measurements agree with observed erosion patterns. Erosion rates are calculated using data from previous wear tests. Magnitudes and trends in the rates are correlated with both previous and subsequent wear tests. Laser-induced fluorescence is demonstrated to be a technique to measure relative internal erosion rates, and a path is identified for measuring absolute rates. Nomenclature= speed of light, 2:998 10 8 m=s E ij = energy of electronic state i with respect to state j, eV h = Plank's constant, 6:626 10 34 Js f oj = oscillator strength G = gaunt factor g i = degeneracy of state i g = Gaussian line shape, s I = intensity, W=m 2 I SAT = saturation intensity, W=m 2 J D = discharge current, A l = power-broadened line shape, s m C = discharge cathode flow rate, sccm m M = main flow rate, sccm n e = plasma density, cm 3 n i;j = density of state i or j, cm 3 n o = ground-state density, cm 3 P = thruster power, kW R oj = collisional population rate, cm 3 =s T e = electron temperature, eV TH = equivalent NSTAR throttle point V D = discharge voltage, V v = velocity, m=s = homogeneous relaxation rate, Hz = wavelength, m = frequency, Hz = cross section, m 2

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Laser induced fluorescence measurement of ion velocities in the plume of a Hall effect thruster

Cited by 32 publications

References 6 publications

Plasma Properties in the Plume of a Hall Thruster Cluster

Plasma Properties in the Plume of a Hall Thruster Cluster

Analysis of chamber simulations of long collecting probes in high-speed dense plasmas

Measurement of 30-Centimeter Ion Thruster Discharge Cathode Erosion

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