Background Pressure Effects on Internal and Near-Field Ion Velocity Distribution of the BHT-600 Hall Thruster

Nakles, Michael R.; Hargus, William A.

doi:10.2514/6.2008-5101

Cited by 22 publications

(19 citation statements)

References 11 publications

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“…In the somewhat turbulent plasmas typical of Hall effect thrusters, the fluorescence lineshape can also be indicative of the relative motion of the ionization zone as it axially traverses in the periodic breathing mode plasma fluctuation. 8,9 However, care must be taken to ensure that the relative effects of these phenomena are separable. In addition, magnetic (Zeeman effect) and electric (Stark effect) fields may also influence the fluorescence lineshape 10 and must be accounted for when analyzing the lineshapes should the fields be of sufficient magnitude.…”

Section: Laser-induced Fluorescencementioning

confidence: 99%

A Comparison of Ion Acceleration Characteristics for Krypton and Xenon Propellants within a 600 W Hall Effect Thruster

Hargus¹,

Azarnia²,

Nakles³

2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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There is growing interest within the electrostatic propulsion community in 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. This work compares the internal propellant acceleration of krypton within a laboratory medium power Hall effect thruster to historical xenon data for the same thruster. One case matched in propellant particle flux (matched volumetric flow rates) is presented. The measurements consist of laser-induced fluorescence velocimetry extending approximately the anode to 10 mm outside the thruster into plume along the center of the coaxial acceleration channel. The results show that the acceleration process for krypton is more gradual and produces a lower electric field. As a result, energy conversion is lower than xenon for this flow matched case. In addition, there is clear evidence of ionization throughout the acceleration channel. This may explain a lower performance for krypton as this particular appears to have low propellant utilization. It is not known to what extent the less oscillatory plasma and/or the lower ionization cross-section of the krypton discharge produced this difference relative to xenon.

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Section: Laser-induced Fluorescencementioning

confidence: 99%

A Comparison of Ion Acceleration Characteristics for Krypton and Xenon Propellants within a 600 W Hall Effect Thruster

Hargus¹,

Azarnia²,

Nakles³

2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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“…In the somewhat turbulent plasmas typical of Hall effect thrusters, the fluorescence lineshape can also be indicative of the relative motion of the ionization zone as it axially traverses in the periodic breathing mode plasma fluctuation. 19,20 However, care must be taken to ensure that the relative effects of these phenomena are separable. In addition, magnetic (Zeeman effect) and electric (Stark effect) fields may also influence the fluorescence lineshape 21 and must be accounted for when analyzing the lineshapes should the fields be of sufficient magnitude.…”

Section: Laser-induced Fluorescencementioning

confidence: 99%

Investigation of Singly Ionized Iodine Spectroscopy in Support of Electrostatic Propulsion Diagnostics Development

Hargus¹,

Lubkeman²,

Remy³

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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This effort examines the spectroscopy of the second spectrum of the iodine atom (I II) in order to determine one, or more, useful transitions for laser-induced fluorescence of an accelerated atomic iodine singly charged ion (I + ). While the second spectrum of iodine has been analyzed, it is not particularly well characterized. Nor has it been studied substantially within a plasma such as those of interest to the spacecraft propulsion community. Our goal is to examine the spectral data available in the literature and determine transitions suitable for development into diagnostics tools, such as laserinduced fluorescence (LIF), to examine the plasma acceleration within an electro-static plasma propulsion thruster. While xenon remains the preferred propellant for electrostatic spacecraft propulsion, a number of alternative propellants are being analyzed in various laboratories. Some of the propellants that have been investigated in the recent literature include krypton, bismuth, and iodine. Of these alternative propellant candidates, iodine is the least well investigated. However, due to its close mass (127 versus 131 amu) compared to xenon, it has strong potential for use as an electro-static propulsion propellant. Iodine's benefits include a solid density of 4.9 g/cc, a low boiling point of 183 • C. Compared to xenon storage density of 1.2 g/cc at 2,000 psi, or the bismuth boiling point of 1,564 • C, there appear to be system level advantages to iodine fueled electrostatic spacecraft propulsion. This effort focuses on the development of a laser-induced fluorescence diagnostic tool for the iodine ion.

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“…where ( ) is the energy distribution of species i; ( ) is the excitation cross sections for a particle i, with energy , with a particle j to produce emission at λ ; and is the velocity of particle i. Excitation cross sections for neutral-electron and neutral-ion collisions are determined empirically from Chiu et al 18 and Sommerville 19 . Assuming a Maxwellian electron energy distribution, is determined as a function of the electron temperature, .…”

Section: Electron Temperature Measurementsmentioning

confidence: 99%

Comparison of Numerical and Experimental Time-Resolved Near-Field Hall Thruster Plasma Properties

Gonzales¹,

Scharfe²,

Koo³

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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The breathing mode of a xenon 600W Hall effect thruster has been studied using both temporally resolved experimental data and numerical modeling. Fluctuations in xenon neutral NIR (810-835 nm) emission in the near field thruster plume have been measured at 1 μs resolution using a high-speed intensified charge coupled device (ICCD). Oscillations in electron temperature, 3-9 eV, have been inferred using a collisional-radiative model and a two-line ratio method. The time-resolved emission and electron temperature measurements are then used to assess the accuracy of the numerical model HPHall.Simulations were found to be consistent with a -68̊ phase delay measured between discharge current and electron temperature cycles, but were unable to predict the magnitude of oscillations observed.

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Background Pressure Effects on Internal and Near-Field Ion Velocity Distribution of the BHT-600 Hall Thruster

Cited by 22 publications

References 11 publications

A Comparison of Ion Acceleration Characteristics for Krypton and Xenon Propellants within a 600 W Hall Effect Thruster

A Comparison of Ion Acceleration Characteristics for Krypton and Xenon Propellants within a 600 W Hall Effect Thruster

Investigation of Singly Ionized Iodine Spectroscopy in Support of Electrostatic Propulsion Diagnostics Development

Comparison of Numerical and Experimental Time-Resolved Near-Field Hall Thruster Plasma Properties

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