Local Plasma Parameter Measurements by Nearwall Probes Inside the SPT Accelerating Channel Under Thruster Operation with Kr

Kim, Vladimir; Grdlichko, D. P.; Козлов, В. І.; Lazourenko, Alexei; Popov, G.F.; Skrylnikov, Alexander

doi:10.2514/6.2002-4108

Cited by 14 publications

(16 citation statements)

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“…The mixed mobility model in the current version more correctly places the peak electron temperature and electric field inside the discharge chamber. The maximum electron temperatures are 30 and 26 eV for the original and current versions, respectively, which are both consistent with experiments that typically report peak electron temperatures that are around 10% of the discharge voltage [21,27,[37][38][39][51][52][53]. Note that setting α p =1.0, is equivalent to imposing "pure" Bohm diffusion in the plume.…”

Section: American Institute Of Aeronautics and Astronauticssupporting

confidence: 81%

“…The plasma properties predicted by the code are in good agreement with experimental measurements of the SPT-100 and other Hall thrusters [21,27,[37][38][39]41,[51][52][53] as well as plasma simulations of the SPT-100 [15,47,49,50]. The plasma response exhibits a high neutral density at the anode that decays monotonically due to the effects of ionization, a peak in the plasma density occurring approximately twothirds of the channel length downstream of the anode, a peak in the electron temperature occurring near the maximum in the magnetic field profile, and a plasma potential profile that begins to decrease near the peak of the plasma density (i.e., an electric field profile that closely follows the magnetic field profile).…”

Section: Plasma Response and Performance Predictionssupporting

confidence: 70%

“…Figure 7 and Figure 8 compares electron temperature and axial electric field predictions from the original version of HPHALL-2 with the standard mobility model (i.e., α=0.1 everywhere) and from HPHALL-2 with the mixed mobility model using α dc =0.035 and α p =1.0. The original version predicts peak electron temperature and electric field strengths downstream of the exit plane, which is not consistent with experimental data [21,27,[37][38][39][51][52][53]. The mixed mobility model in the current version more correctly places the peak electron temperature and electric field inside the discharge chamber.…”

Section: American Institute Of Aeronautics and Astronauticsmentioning

confidence: 70%

See 2 more Smart Citations

Wall Sheath and Electron Mobility Modeling in Hybrid-PIC Hall Thruster Simulations

Hofer¹,

Mikellides²,

Katz³

et al. 2007

43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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Progress on the development of physics-based modeling tools aimed at predicting the service life of Hall thrusters is discussed. Modifications of the wall sheath and electron mobility models in the hybrid fluid/particle-in-cell computer code HPHall-2 are made and the effects of these changes on the plasma parameters and thruster performance are assessed. The wall sheath model of Hobbs and Wesson [Plasma Physics, 9, 85-87 (1967)] has been adopted, resulting in modifications to the predicted sheath potentials that are relevant to the modeling of high specific impulse Hall thrusters. Experiments with a widely used mixed-mobility model of the cross-field electron transport is presented that enables the simultaneous prediction of thrust and discharge current in agreement with experimental data. Taken together, these code modifications have improved the predictive capability of HPHALL-2 to serve as an input for studies of Hall thruster erosion.

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Section: American Institute Of Aeronautics and Astronauticssupporting

confidence: 81%

Section: Plasma Response and Performance Predictionssupporting

confidence: 70%

Section: American Institute Of Aeronautics and Astronauticsmentioning

confidence: 70%

See 1 more Smart Citation

Wall Sheath and Electron Mobility Modeling in Hybrid-PIC Hall Thruster Simulations

Hofer¹,

Mikellides²,

Katz³

et al. 2007

43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

View full text Add to dashboard Cite

show abstract

“…Trim coils have been used extensively in Hall thrusters for decades, dating back at least to the work of Morosov, et al 37,38 More recently, Kim, et al has experimented with internal trim coils on xenon and krypton mixtures. 39,40 Other implementations of internal trim coils are discussed in Refs. 33 and 41-43.…”

Section: Hall Thrustermentioning

confidence: 99%

High-Specific Impulse Hall Thrusters, Part 1: Influence of Current Density and Magnetic Field

Hofer¹,

Jankovsky

Gallimore

2006

Journal of Propulsion and Power

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A laboratory-model Hall thruster with a magnetic circuit designed for high-specific impulse (2000-3000 s) was evaluated to determine how current density and magnetic field affect thruster operation. Results have shown for the first time that a minimum current density and optimum magnetic field shape exist at which efficiency will monotonically increase with specific impulse. At the nominal mass flow rate of 10 mg/s and between discharge voltages of 300 and 1000 V, total specific impulse and total efficiency ranged from 1600 to 3400 s and 51 to 61%, respectively. Comparison with a similar thruster showed how efficiency can be optimized for specific impulse by varying the shape of the magnetic field. Plume divergence decreased from a maximum of 48 deg at 400 V to a minimum of 35 deg at 1000 V, but increased between 300 and 400 V as the likely result of a large increase in discharge current oscillations. The breathing-mode frequency continuously increased with voltage, from 14.5 kHz at 300 V to 22 kHz at 1000 V, in contrast to other Hall thrusters where a sharp decrease of the breathing-mode frequency was found to coincide with increasing electron current and decreasing efficiency. These findings suggest that efficient, high-specific impulse operation was enabled through the regulation of the electron current with the applied magnetic field. . Associate Fellow AIAA. η t = total efficiency θ = azimuthal coordinate direction ∇ z B r = axial gradient of the centerline radial magnetic field

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“…Flush-mounted Langmuir probes have been used successfully in the past to measure erosion-relevant properties in Hall thrusters. 10,[13][14][15][16][17][18][19][20][21] These probes were used to measure the local plasma potential and electron temperature along each wall, with a focus on the exit plane region that is characterized by high erosion rates in unshielded Hall thrusters. The thruster was operated across a wide range of discharge voltages and power levels to characterize the magnetic shielding across the HERMeS throttle table, especially at high specific impulse operation.…”

Section: Introductionmentioning

confidence: 99%

Near-Surface Plasma Characterization of the 12.5-kW NASA TDU1 Hall Thruster

Shastry

Huang²,

Kamhawi³

2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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To advance the state-of-the-art in Hall thruster technology, NASA is developing a 12.5-kW, high-specific-impulse, high-throughput thruster for the Solar Electric Propulsion Technology Demonstration Mission. In order to meet the demanding lifetime requirements of potential missions such as the Asteroid Redirect Robotic Mission, magnetic shielding was incorporated into the thruster design. Two units of the resulting thruster, called the Hall Effect Rocket with Magnetic Shielding (HERMeS), were fabricated and are presently being characterized. The first of these units, designated the Technology Development Unit 1 (TDU1), has undergone extensive performance and thermal characterization at NASA Glenn Research Center. A preliminary lifetime assessment was conducted by characterizing the degree of magnetic shielding within the thruster. This characterization was accomplished by placing eight flush-mounted Langmuir probes within each discharge channel wall and measuring the local plasma potential and electron temperature at various axial locations. Measured properties indicate a high degree of magnetic shielding across the throttle table, with plasma potential variations along each channel wall being ≤ 5 V and electron temperatures being maintained at ≤ 5 eV, even at 800 V discharge voltage near the thruster exit plane. These properties indicate that ion impact energies within the HERMeS will not exceed 26 eV, which is below the expected sputtering threshold energy for boron nitride. Parametric studies that varied the facility backpressure and magnetic field strength at 300 V, 9.4 kW, illustrate that the plasma potential and electron temperature are insensitive to these parameters, with shielding being maintained at facility pressures 3X higher and magnetic field strengths 2.5X higher than nominal conditions. Overall, the preliminary lifetime assessment indicates a high degree of shielding within the HERMeS TDU1, effectively mitigating discharge channel erosion as a life-limiting mechanism.

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Local Plasma Parameter Measurements by Nearwall Probes Inside the SPT Accelerating Channel Under Thruster Operation with Kr

Cited by 14 publications

References 0 publications

Wall Sheath and Electron Mobility Modeling in Hybrid-PIC Hall Thruster Simulations

Wall Sheath and Electron Mobility Modeling in Hybrid-PIC Hall Thruster Simulations

High-Specific Impulse Hall Thrusters, Part 1: Influence of Current Density and Magnetic Field

Near-Surface Plasma Characterization of the 12.5-kW NASA TDU1 Hall Thruster

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