Experimental and Numerical Examination of a Hall Thruster Plume (Preprint)

Nakles, Michael R.; Brieda, Lubos; Reed, Garrett; Hargus, William A.; Spicer, Randy L.

doi:10.21236/ada473510

Cited by 6 publications

(7 citation statements)

References 10 publications

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“…There is evidence, however, that the presence of physical probes near regions of propellant ionization and acceleration can perturb the operation of the discharge [24]. So, optical diagnostics, including passive measurements like emission studies [25,26] and active measurements like laser-induced fluorescence (LIF) [11,12], are preferable for experimentally investigating breathing mode dynamics. Only recently have the requisite time-resolved optical diagnostics become available for a close, noninvasive examination of the interior of the discharge channel with high spatial and temporal resolution.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved laser-induced fluorescence diagnostics for electric propulsion and their application to breathing mode dynamics

Young¹,

Fabris²,

MacDonald-Tenenbaum³

et al. 2018

Plasma Sources Sci. Technol.

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Several techniques have been developed recently for performing time-resolved laser-induced fluorescence (LIF) measurements in oscillating plasmas. One of the primary applications is characterizing plasma fluctuations in devices like Hall thrusters used for space propulsion. Optical measurements such as LIF are nonintrusive and can resolve properties like ion velocity distribution functions with high resolution in velocity and physical space. The goals of this paper are twofold. First, the various methods proposed by the community for introducing time resolution into the standard LIF measurement of electric propulsion devices are reviewed and compared in detail. Second, one of the methods, the sample-hold technique, is enhanced by parallelizing the measurement hardware into several signal processing channels that vastly increases the data acquisition rate. The new system is applied to study the dynamics of ionization and ion acceleration in a commercial BHT-600 Hall thruster undergoing unforced breathing mode oscillations in the 44-49 kHz range. A very detailed experimental picture of the common breathing mode ionization instability emerges, in close agreement with established theory and numerical simulations.

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Section: Introductionmentioning

confidence: 99%

Time-resolved laser-induced fluorescence diagnostics for electric propulsion and their application to breathing mode dynamics

Young¹,

Fabris²,

MacDonald-Tenenbaum³

et al. 2018

Plasma Sources Sci. Technol.

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“…Spacecraft interaction models have been developed which utilize near exit plane plasma information to estimate plume divergence and interactions with spacecraft surfaces. 1 A major limitation of these models is the accuracy of available near exit plane plume data for validation. The goal of this study is to characterize the near plume velocity field of a 600 W Hall thruster using excited state ionic xenon laser-induced fluorescence (LIF).…”

Section: Introductionmentioning

confidence: 99%

Near Plume laser Induced Fluorescence Velocity Measurements of a 600 W Hall Thruster

Hargus¹,

Charles²

2008

44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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“…Past experimental measurements of the Hall thruster ion source beam indicated that the Debye length ranged from ϳ0.05 to ϳ1 mm throughout the plume from 8 to 20 channel centerline diameters downstream ͑CCDD͒ from the exit plane. 13 Thus, the 0.5 mm gap configuration is expected to be less than or equal to 10 Debye lengths for all locations studied with the nested Faraday probe. The 1.5 mm gap configuration is greater than 10 Debye lengths, and is oversized to highlight effects of a gap width greater than the 10 Debye length design criteria.…”

Section: B Nested Faraday Probementioning

confidence: 95%

Evaluation of ion collection area in Faraday probes

Brown

Gallimore

2010

Review of Scientific Instruments

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A Faraday probe with three concentric rings was designed and fabricated to assess the effect of gap width and collector diameter in a systematic study of the diagnostic ion collection area. The nested Faraday probe consisted of two concentric collector rings and an outer guard ring, which enabled simultaneous current density measurements on the inner and outer collectors. Two versions of the outer collector were fabricated to create gaps of 0.5 and 1.5 mm between the rings. Distribution of current density in the plume of a low-power Hall thruster ion source was measured in azimuthal sweeps at constant radius from 8 to 20 thruster diameters downstream of the exit plane with variation in facility background pressure. A new analytical technique is proposed to account for ions collected in the gap between the Faraday probe collector and guard ring. This method is shown to exhibit excellent agreement between all nested Faraday probe configurations, and to reduce the magnitude of integrated ion beam current to levels consistent with Hall thruster performance analyses. The technique is further studied by varying the guard ring bias potential with a fixed collector bias potential, thereby controlling ion collection in the gap. Results are in agreement with predictions based on the proposed analytical technique. The method is applied to a past study comparing the measured ion current density profiles of two Faraday probe designs. These findings provide new insight into the nature of ion collection in Faraday probe diagnostics, and lead to improved accuracy with a significant reduction in measurement uncertainty.

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Experimental and Numerical Examination of a Hall Thruster Plume (Preprint)

Cited by 6 publications

References 10 publications

Time-resolved laser-induced fluorescence diagnostics for electric propulsion and their application to breathing mode dynamics

Time-resolved laser-induced fluorescence diagnostics for electric propulsion and their application to breathing mode dynamics

Near Plume laser Induced Fluorescence Velocity Measurements of a 600 W Hall Thruster

Evaluation of ion collection area in Faraday probes

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