Low-Power Operation and Plasma Characterization of a Qualification Model SPT-140 Hall Thruster

Garner, Charles E.; Jorns, Benjamin; Hofer, Richard R.; Liang, Raymond; Delgado, Jorge

doi:10.2514/6.2015-3720

Cited by 8 publications

(4 citation statements)

References 4 publications

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“…The first test program investigated the performance and operation of the Development Model 4 (DM4) thruster at discharge powers of 0.23 to 6.0 kW, and observed stable operation and performance over this range [14]. The second test program repeated many of the same measurements on the flight-model Qualification Model 2 (QM002) thruster with similar results [15]. Recently, a study was carried out to examine the effects of facility background pressure on thruster performance [1] with the aim of predicting thrust in vacuum conditions.…”

Section: Introductionmentioning

confidence: 96%

Facility pressure effects on a Hall thruster with an external cathode: I. Numerical simulations

Ortega

Mikellides

Chaplin

et al. 2020

Plasma Sources Sci. Technol.

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We employ the 2D (r-z) code Hall2De to conduct numerical simulations of the SPT-140, a Hall thruster that operates with an external hollow cathode. The simulations are informed by direct measurements of the plasma conditions in the acceleration channel that were obtained using the laser-induced fluorescence technique. We validate our simulation results with additional plasma measurements, wear test erosion rates, and performance data as a function of background pressure. The comparisons of the simulation results with thrust measurements provide insight into the longstanding question of how background pressure affects Hall thruster performance. We find that in thrusters with an external cathode changes in the thrust with varying backpressure can be partially explained by changes in the plasma density near the cathode. We argue that such changes in the density affect the voltage coupling and, eventually, the thrust. However, accounting for this mechanism alone in the simulations over-predicts the thrust measured during ground tests for backpressures less than 10 μTorr. Also, at these backpressures, the measurements showed a higher rate of change of the thrust compared to the simulations. We propose that one explanation for this discrepancy is that the acceleration region may be axially shifting downstream with decreasing backpressure. Though possible, we also recognize that such shifts are not observed in LIF measurements at the lowest pressures for which such diagnostics are possible. We discuss alternative explanations in Part II of this article.

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Section: Introductionmentioning

confidence: 96%

Facility pressure effects on a Hall thruster with an external cathode: I. Numerical simulations

Ortega

Mikellides

Chaplin

et al. 2020

Plasma Sources Sci. Technol.

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“…13 and 14 show performance levels that are similar to what has been reported by SSL and Snyder. 12,13,14 Additionally, comparison of segment 1 and 2 results indicated almost identical performance levels, further confirming that the thruster's closed-loop operation results in similar thruster operation as open-loop operation. Table 4 presents a summary of the ratio of the discharge current, anode mass flow rate, and thrust between open-loop and closed-loop thruster operation.…”

Section: Spt-140 Thruster Integration Test Resultsmentioning

confidence: 56%

Integration Tests of the 4 kW-class High Voltage Hall Accelerator Power Processing Unit with the HiVHAc and the SPT-140 Hall Effect Thrusters

Kamhawi

Pinero²,

Haag³

et al. 2016

52nd AIAA/SAE/ASEE Joint Propulsion Conference

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NASA's Science Mission Directorate is sponsoring the development of a 4 kW-class Hall propulsion system for implementation in NASA science and exploration missions. The main components of the system include the High Voltage Hall Accelerator (HiVHAc), an engineering model power processing unit (PPU) developed by Colorado Power Electronics, and a xenon flow control module (XFCM) developed by VACCO Industries. NASA Glenn Research Center is performing integrated tests of the Hall thruster propulsion system. This paper presents results from integrated tests of the PPU and XFCM with the HiVHAc engineering development thruster and a SPT-140 thruster provided by Space System Loral. The results presented in this paper demonstrate thruster discharge initiation along with open-loop and closed-loop control of the discharge current with anode flow for both the HiVHAc and the SPT-140 thrusters.Integrated tests with the SPT-140 thruster indicated that the PPU was able to repeatedly initiate the thruster's discharge, achieve steady state operation, and successfully throttle the thruster between 1.5 and 4.5 kW. The measured SPT-140 performance was identical to levels reported by Space Systems Loral.

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“…Year observation" in a given population (Aschengrau and Seage, 2008), that is, time is intrinsic to the denominator in rate calculations 10 . For our purpose, we calculate spacecraft-time instead of person-time, which is accrued only when the spacecraft is launched and until it is retired or completely fails on orbit.…”

Section: -Year Rolling Average Anomaly Per Spacecraftmentioning

confidence: 99%

“…The authors used two qualification models of the thruster, one to undergo qualification and acceptance testing and has accumulated several thousand hours of operation, and one to undergo plume characterization and other performance testing. The performance evaluation of the second model is discussed in Garner et al (2015) in which the authors conclude that the SPT-140 is a "viable candidate for NASA missions requiring power throttling down to low thruster input power". Dankanich et al (2009) develop a qualification standard for electric thrusters, which have very different lifetime qualification issues than chemical thrusters.…”

Section: Peculiarities and Limitations Of Observational Studiesmentioning

confidence: 99%

Electric propulsion reliability: Statistical analysis of on-orbit anomalies and comparative analysis of electric versus chemical propulsion failure rates

Saleh

Geng

et al. 2017

Acta Astronautica

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With a few hundred spacecraft launched to date with electric propulsion (EP), it is possible to conduct an epidemiological study of EP's on orbit reliability. The first objective of the present work was to undertake such a study and analyze EP's track record of on orbit anomalies and failures by different covariates. The second objective was to provide a comparative analysis of EP's failure rates with those of chemical propulsion. Satellite operators, manufacturers, and insurers will make reliability-and risk-informed decisions regarding the adoption and promotion of EP on board spacecraft. This work provides evidence-based support for such decisions. After a thorough data collection, 162 EP-equipped satellites launched between January 1997 and December 2015 were included in our dataset for analysis. Several statistical analyses were conducted, at the aggregate level and then with the data stratified by severity of the anomaly, by orbit type, and by EP technology. Mean Time To Anomaly (MTTA) and the distribution of the time to (minor/major) anomaly were investigated, as well as anomaly rates.The important findings in this work include the following: (1) Post-2005, EP's reliability has outperformed that of chemical propulsion; (2) Hall thrusters have robustly outperformed chemical propulsion, and they maintain a small but shrinking reliability advantage over gridded ion engines. Other results were also provided, for example the differentials in MTTA of minor and major anomalies for gridded ion engines and Hall thrusters. It was shown that: (3) Hall thrusters exhibit minor anomalies very early on orbit, which might be indicative of infant anomalies, and thus would benefit from better ground testing and acceptance procedures; (4) Strong evidence exists that EP anomalies (onset and likelihood) and orbit type are dependent, a dependence likely mediated by either the space environment or differences in thrusters duty cycles; (5) Gridded ion thrusters exhibit both infant and wear-out failures, and thus would benefit from a reliability growth program that addresses both these types of problems.

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Low-Power Operation and Plasma Characterization of a Qualification Model SPT-140 Hall Thruster

Cited by 8 publications

References 4 publications

Facility pressure effects on a Hall thruster with an external cathode: I. Numerical simulations

Facility pressure effects on a Hall thruster with an external cathode: I. Numerical simulations

Integration Tests of the 4 kW-class High Voltage Hall Accelerator Power Processing Unit with the HiVHAc and the SPT-140 Hall Effect Thrusters

Electric propulsion reliability: Statistical analysis of on-orbit anomalies and comparative analysis of electric versus chemical propulsion failure rates

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