Uncertainty in Inverted Pendulum Thrust Measurements

Mackey, Jeffrey R.; Haag, Thomas; Kamhawi, Hani; Hall, Scott J.; Peterson, Peter Y.

doi:10.2514/6.2018-4516

Cited by 20 publications

(3 citation statements)

References 14 publications

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“…The VF-8 facility, shown in Figure 17, is a 1.5-m diameter, 4.5-m long chamber whose pumping train (including four 35inch diameter oil diffusion pumps) can achieve a base pressure of ~4 x 10 -7 Torr. A displacement-style, invertedpendulum thrust stand of heritage GRC design [14] was installed in VF-8 and tuned for low-thrust measurements with a maximum uncertainty [15] of ±2 %. Cathode testing for the NASA-H64M-LM was conducted in VF-56.…”

Section: A Vacuum Test Facilitiesmentioning

confidence: 99%

Development of a High-Propellant Throughput Small Spacecraft Electric Propulsion System to Enable Lower Cost NASA Science Missions

Benavides

Kamhawi

Myers³

et al. 2019

AIAA Propulsion and Energy 2019 Forum

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This paper describes recent progress at the NASA Glenn Research Center (GRC) in the development and demonstration of an integrated high-propellant throughput small spacecraft electric propulsion (HT-SSEP) system based on a Hall-effect thruster. A center-mounted cathode and an innovative magnetic circuit topology were implemented in the design of the Hall-effect thruster to achieve high-propellant throughput, high performance, and efficient packaging. To minimize technical risk, the HT-SSEP development approach sought to limit design features and materials to those with a clear path-to-flight. A propellant throughput capability of greater than 100 kg at a minimum thruster efficiency of 50% was targeted. The proof-of-concept NASA-H64M laboratory model (LM) thruster was designed, fabricated, and tested at GRC in fiscal year 2018. The thruster development leveraged heritage Hall-effect thruster design and manufacturing processes wherever appropriate. Recent NASA advances in Hall-effect thruster technology were also leveraged. A scalable discharge power supply (DPS) capable of powering the H64M-LM was developed, then demonstrated as part of an integrated system test. The DPS uses commercial off-the-shelf components with spaceflight equivalents. A keeper supply with DC ignitor was breadboarded, then demonstrated with a laboratory cathode. Finally, feed system trade studies were performed to ascertain what feed system architecture might be appropriate for an HT-SSEP system. This paper details the motivations for the project, the development approach, the chosen sub-system architectures, design considerations, and test results.

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Section: A Vacuum Test Facilitiesmentioning

confidence: 99%

Development of a High-Propellant Throughput Small Spacecraft Electric Propulsion System to Enable Lower Cost NASA Science Missions

Benavides

Kamhawi

Myers³

et al. 2019

AIAA Propulsion and Energy 2019 Forum

Self Cite

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“…The specific impulse I sp and anode efficiency η a were defined as I sp = T/ ṁa g and η a = T 2 /2 ṁa P d , respectively, where ṁa is the total anode mass flow rate, and P d is the discharge power. The root sum of square method was used to calculate the total error [35]. The derived error bars in figures 3(a)-(c) include the statistical error of the measurement, which indicates the 95% confidence interval of threetimes thrust measurement at each set point in table 1, and the inherent error of the thrust stand due to the thermal drift.…”

Section: Resultsmentioning

confidence: 99%

Argon admixture-driven enhanced ionization and performance of a 5 kW Hall thruster on krypton

Lee,

Brabston,

Lev

et al. 2024

J. Phys. D: Appl. Phys.

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Utilizing alternative propellants has been recognized as a strategy to reduce the total cost of propellants in electric propulsion-based missions. The aim of this study is to quantify the Hall effect thruster (HET) performance and operating characteristics using a Kr-Ar mixture to enable mission designers to evaluate the impact on mission and spacecraft design. We present the performance and plume plasma properties of the P5 5 kW-class HET operated with a Kr-Ar mixture with Ar volumetric flow rate fractions from 0 to 100%. The thruster is characterized at discharge power levels of 2.6 kW and 4.1 kW at constant discharge current and voltage over the range of Ar fractions. Despite higher ionization energy and lower mass of Ar, the thruster exhibited a similar level of thrust within 2% when comparing the pure Kr and 26%-Ar mixture cases. The derived ion energy distribution functions and analytical modeling suggest that the characteristic length for the ionization region is extended as the Ar fraction increases. The increased residence time of Kr at the extended ionization region and background energetic electrons from the ionized Ar neutrals are considered to cause this enhanced ionization of the injected Kr neutrals, leading to a 6% higher Kr ion density at the 26%-Ar case even at the 16% reduced injected neutral density than in the pure Kr case. The enhanced Kr ionization and generated Ar ions in the 26%-Ar case consequently led to a comparable thrust with that of the pure Kr case. The study indicates that mixing Ar with approximately 26% volumetrically with Kr can provide a similar or even higher thrust performance at the same discharge power. This will be particularly advantageous for various space missions that require high impulses by reducing the total cost of the propellant.

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“…This thermal drift was accounted for in post-processing of the thrust values. Using the analysis technique developed by Mackey [22], which includes effects such as calibration variation, the weight of the thruster and stand, and inclination uncertainty, the uncertainty of the measurements reported here was determined to be approximately 0.8% of the highest measured thrust of this campaign, or approximately 36 mN. This value is dominated by uncertainty and resolution of the inclination control.…”

Section: E Thrust Standmentioning

confidence: 88%

High Power Demonstration of a 100 kW Nested Hall Thruster System

Shark

Hall

Jorns

et al. 2019

AIAA Propulsion and Energy 2019 Forum

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The XR-100 team successfully completed high power system testing of a Nested Hall Thruster system made up of the X3 Nested Hall Thruster, a modular Power Processing Unit, and a 5 valve Mass Flow Controller as the culmination of work performed under a NASA NextSTEP program. The test campaign attained several key records to date, including highest directly measured thrust of an electric propulsion (EP) string, highest demonstrated current of an EP string, and highest power operation of an EP string at thermal equilibrium published to date. Most importantly, the XR-100 system testing demonstrated that a 100 kW-class Nested Hall Thruster system has comparable performance and behavior to current state-of-the-art mid power Hall Thrusters, validating that the heritage technology can be scaled up to 100+ kW class. In addition to the outlined accomplishments and corresponding system demonstration, design improvements for future development and testing are discussed.

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Uncertainty in Inverted Pendulum Thrust Measurements

Cited by 20 publications

References 14 publications

Development of a High-Propellant Throughput Small Spacecraft Electric Propulsion System to Enable Lower Cost NASA Science Missions

Development of a High-Propellant Throughput Small Spacecraft Electric Propulsion System to Enable Lower Cost NASA Science Missions

Argon admixture-driven enhanced ionization and performance of a 5 kW Hall thruster on krypton

High Power Demonstration of a 100 kW Nested Hall Thruster System

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