Ion Velocity Measurements Within the Acceleration Channel of a Low-Power Hall Thruster

Hargus, William A.; Nakles, Michael R.

doi:10.1109/tps.2008.2003967

Cited by 33 publications

(31 citation statements)

References 13 publications

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“…This transition has been used extensively throughout the electric propulsion community for timeaveraged and time-resolved LIF velocimetry [16,[22][23][24]. Figure 3 depicts the optical train and associated equipment used in this experiment [17,25]. A New Focus Vortex TLB-6917 tunable diode laser is used to seed a TA-7600 VAMP tapered amplifier to achieve a probe beam output power of 82 mW.…”

Section: Laser-induced Fluorescence Velocimetrymentioning

confidence: 99%

Background Pressure Effects on Ion Velocity Distributions in an SPT-100 Hall Thruster

MacDonald-Tenenbaum

Pratt²,

Nakles³

et al. 2019

Journal of Propulsion and Power

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Increased background pressure in vacuum chamber test facilities as compared to on-orbit operation has been shown to influence the operation of electric propulsion devices such as Hall thrusters. This study aims to elucidate the impact of pressure on the ionization and acceleration mechanisms in a stationary plasma thruster, model SPT-100 Hall thruster, using time-averaged and time-resolved laser-induced fluorescence velocimetry. The results are compared for the thruster operating at an applied 300 V (∼4.25 A), with vacuum facility background pressures ranging from 1.7 × 10 −5 to 8.0 × 10 −5 torr. Time-averaged measurements reveal that, in general, an upstream shift in the position of the ionization and acceleration regions occurs as the facility pressure is increased above the nominal 1.7 × 10 −5 torr. Time-resolved measurements, implemented using a sample-hold scheme with 1 μs resolution, emphasize that similar acceleration profiles are present within the Hall thruster discharge channel regardless of background pressure. Measurements taken at 3.5 × 10 −5 torr, where the facility background neutral density is similar to the neutral density emitted from the thruster, unexpectedly show increased ion acceleration over the next highest pressure condition at 5.0 × 10 −5 torr. These results indicate a not-yet well defined balance of the impacts of neutral ingestion, classical and turbulent electron transport on thruster operation, and that the ratio of the background to thruster neutral density is a more relevant benchmark than background pressure alone when evaluating Hall thruster operation.

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Section: Laser-induced Fluorescence Velocimetrymentioning

confidence: 99%

Background Pressure Effects on Ion Velocity Distributions in an SPT-100 Hall Thruster

MacDonald-Tenenbaum

Pratt²,

Nakles³

et al. 2019

Journal of Propulsion and Power

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“…According to the electric probe measurements, the IAR changes location in KM-88 thruster's channel whenever any operating parameter of the thruster is being changed. Independently, a series of works based on LIF measurements focused on acceleration region (AR) location [8][9][10][11][12] were carried out. Ion velocity distribution along the discharge channel was observed in these works for different operating regimes of different thrusters.…”

Section: Introductionmentioning

confidence: 99%

“…For example, the power throttling ratio about 20:1 and discharge current ratio about 15:1 was achieved in recent Hall thruster models [13]. However, papers [7][8][9][10][11][12] illustrate that to change the operating parameters within the throttle ratio it is necessary to correct magnetic field absolute value to conserve the IAR location and, consequently, the erosion rate.…”

Section: Introductionmentioning

confidence: 99%

Investigation into the ionization and acceleration regions shift in a Hall thruster channel

2019

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Location of the ionization and acceleration regions determines erosion belt location and thruster's maximum throughput consequently. For Hall thrusters with wide throttle ratio the location of the ionization and acceleration regions in each operating mode could vary significantly, which makes it difficult to provide necessary throughput for multi-mode operation. In this article, the shift of the ionization and acceleration region location caused by the change of operating mode is studied with the help of numerical method. Numerical investigation was conducted with 1D3V hybrid-PIC simulations. According to the results, the ionization and acceleration regions could move upstream significantly with gas flow rate increase and magnetic field decrease. In addition, it was proved that an increase in the magnetic field gradient shifts the ionization and acceleration region location outside of the channel significantly. The trends obtained in numerical simulations were experimentally testified. The acceleration region trend validation was carried out with electrical probe measurements on a 1.5 kW laboratory Hall thruster. The ionization region shift was validated with the shift of the maximum light intensity of the xenon inside the channel of a 2.3 kW laboratory Hall thruster. Moreover, experimental investigations indicate that the ionization and acceleration regions could move significantly when oscillation mode changes.

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“…suring the electrostatic acceleration of the Kr II must be developed. Similar measurements have been used for xenon fueled electrostatic thrusters for a number of years 2,3 . This work examines theoretical development and application of laser-induced fluorescence (LIF) of a singly charged krypton ion (Kr II) transition within a laboratory Hall effect plasma accelerator.…”

Section: Introductionmentioning

confidence: 88%

Kr II laser-induced fluorescence for measuring plasma acceleration

Hargus

Azarnia

Nakles

2012

Review of Scientific Instruments

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We present the application of laser-induced fluorescence of singly ionized krypton as a diagnostic technique for quantifying the electrostatic acceleration within the discharge of a laboratory cross-field plasma accelerator also known as a Hall effect thruster, which has heritage as spacecraft propulsion. The 728.98 nm Kr II transition from the metastable 5d(4)D(7/2) to the 5p(4)P(5/2)(∘) state was used for the measurement of laser-induced fluorescence within the plasma discharge. From these measurements, it is possible to measure velocity as krypton ions are accelerated from near rest to approximately 21 km/s (190 eV). Ion temperature and the ion velocity distributions may also be extracted from the fluorescence data since available hyperfine splitting data allow for the Kr II 5d(4)D(7/2)-5p(4)P(5/2)(∘) transition lineshape to be modeled. From the analysis, the fluorescence lineshape appears to be a reasonable estimate for the relatively broad ion velocity distributions. However, due to an apparent overlap of the ion creation and acceleration regions within the discharge, the distributed velocity distributions increase ion temperature determination uncertainty significantly. Using the most probable ion velocity as a representative, or characteristic, measure of the ion acceleration, overall propellant energy deposition, and effective electric fields may be calculated. With this diagnostic technique, it is possible to nonintrusively characterize the ion acceleration both within the discharge and in the plume.

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Ion Velocity Measurements Within the Acceleration Channel of a Low-Power Hall Thruster

Cited by 33 publications

References 13 publications

Background Pressure Effects on Ion Velocity Distributions in an SPT-100 Hall Thruster

Background Pressure Effects on Ion Velocity Distributions in an SPT-100 Hall Thruster

Investigation into the ionization and acceleration regions shift in a Hall thruster channel

Kr II laser-induced fluorescence for measuring plasma acceleration

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