Performance and Environmental Test Results of the High Voltage Hall Accelerator Engineering Development Unit

Kamhawi, Hani; Haag, Thomas; Huang, Wensheng; Shastry, Rohit; Pinero, Luis R.; Peterson, Todd; Mathers, Alex

doi:10.2514/6.2012-3854

Cited by 10 publications

(13 citation statements)

References 19 publications

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“…Compared to the previous iteration, which is the EDU1, the EDU2 has better thermal management, simpler design for the channel replacement mechanism, and superior voltage isolation. The EDU2 has undergone the performance acceptance test (PAT), 3 a vibration test, 3 a plume divergence characterization test, 4 an in-situ mechanism actuation tests (unpublished), and a single-string integration test (SSIT). 5 The background pressure study described in this paper was performed during the SSIT in April and May of 2013.…”

Section: Introductionmentioning

confidence: 99%

Effect of Background Pressure on the Plasma Oscillation Characteristics of the HiVHAc Hall Thruster

Huang¹,

Kamhawi²,

Lobbia³

et al. 2014

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)Air Force Research Laboratory (AFMC) AFRL/RQR 5 Pollux Drive SPONSOR/MONITOR'S REPORTEdwards AFB CA 93524-7048 NUMBER(S) AFRL-RQ-ED-TP-2014-226 DISTRIBUTION / AVAILABILITY STATEMENTDistribution A: Approved for Public Release; Distribution Unlimited SUPPLEMENTARY NOTESTechnical paper presented at 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Cleveland, OH, 28-30 July, 2014. PA#14392 ABSTRACTDuring a single-string integration test of the NASA HiVHAc Hall thruster, a number of plasma diagnostics were implemented to study the effect of varying facility background pressure on thruster operation. These diagnostics characterized the thruster performance, the plume, and the plasma oscillations in the thruster. Thruster performance and plume characteristics as functions of background pressure were previously published. This paper will focus on changes in the plasma oscillation characteristics with changing background pressure. The diagnostics used to study plasma oscillations include a high-speed camera and a set of high-speed Langmuir probes. The results show a rise in the oscillation frequency of the "breathing" mode with rising background pressure, which is hypothesized to be due to a shortening acceleration/ionization zone. An attempt is made to apply a simplified ingestion model to the data. The combined results are used to estimate the maximum acceptable background pressure for performance and wear testing. During a single-string integration test of the NASA HiVHAc Hall thruster, a number of plasma diagnostics were implemented to study the effect of varying facility background pressure on thruster operation. These diagnostics characterized the thruster performance, the plume, and the plasma oscillations in the thruster. Thruster performance and plume characteristics as functions of background pressure were previously published. This paper will focus on changes in the plasma oscillation characteristics with changing background pressure. The diagnostics used to study plasma oscillations include a high-speed camera and a set of high-speed Langmuir probes. The results show a rise in the oscillation frequency of the "breathing" mode with rising background pressure, which is hypothesized to be due to a shortening acceleration/ionization zone. An attempt is made to apply a simplified ingestion model to the data. The combined results are used to estimate the maximum acceptable background pressure for performance and...

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Section: Introductionmentioning

confidence: 99%

Effect of Background Pressure on the Plasma Oscillation Characteristics of the HiVHAc Hall Thruster

Huang¹,

Kamhawi²,

Lobbia³

et al. 2014

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“…In section IIIA, the performance evaluation of HiVHAc EDU for the entire throttle operating conditions is presented and compared to results from the performance acceptance test (PAT) that were reported in 2012. 13 In Section IIIB, results from a pressure sensitivity study that was performed at 7 throttle conditions are presented. Finally, Section IIIC presents the V-I profiles that were acquired at different facility background conditions for different thruster anode flow rates and electromagnet currents.…”

Section: Resultsmentioning

confidence: 99%

“…Test results indicate performance levels that are lower than levels demonstrated during the performance acceptance test (PAT) of EDU in VF12. 13 Table 2 below summarizes the HiVHAc EDU thruster performance in VF5 and VF12 at selected operating points. Figure 7 presents the discharge specific impulse (left) and efficiency (right) for the VF5 and VF12 tests for HiVHAc EDU thruster operation at discharge voltages of 300, 500, and 650 V.…”

Section: A Performance Characterizationmentioning

confidence: 99%

“…13 The EDU thruster is designed to operate at a peak discharge power of 3.9 kW and at discharge voltages up to 650 V. The thruster incorporates an in-situ discharge channel replacement mechanism for life extension. The thruster development plan has been reported earlier; 13  The Colorado Power Electronics (CPE) brassboard (BB) power processing unit (PPU), designated BB 1 PPU; 14,15  A 15 kW 600 V capable power supply that was remotely operated with control software created by The Aerospace Corp., and American Institute of Aeronautics and Astronautics  Two laboratory xenon feed systems.…”

Section: Experimental Apparatusmentioning

confidence: 99%

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Investigation of the Effects of Facility Background Pressure on the Performance and Operation of the High Voltage Hall Accelerator

Kamhawi¹,

Huang²,

Haag³

et al. 2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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The National Aeronautics and Space Administration (NASA) Science Mission Directorate In-Space Propulsion Technology office is sponsoring NASA Glenn ResearchCenter to develop a 4 kW-class Hall thruster propulsion system for implementation in NASA science missions. A study was conducted to assess the impact of varying the facility background pressure on the High Voltage Hall Accelerator (HiVHAc) thruster performance and voltage-current characteristics. This present study evaluated the HiVHAc thruster performance in the lowest attainable background pressure condition at NASA GRC Vacuum Facility 5 to best simulate space-like conditions. Additional tests were performed at selected thruster operating conditions to investigate and elucidate the underlying physics that change during thruster operation at elevated facility background pressure. Tests were performed at background pressure conditions that are three and ten times higher than the lowest realized background pressure. Results indicated that the thruster discharge specific impulse and efficiency increased with elevated facility background pressure. The voltage-current profiles indicated a narrower stable operating region with increased background pressure. Experimental observations of the thruster operation indicated that increasing the facility background pressure shifted the ionization and acceleration zones upstream towards the thruster's anode. Future tests of the HiVHAc thruster are planned at background pressure conditions that are expected to be two to three times lower than what was achieved during this test campaign. These tests will not only assess the impact of reduced facility background pressure on thruster performance, voltage-current characteristics, and plume properties; but will also attempt to quantify the magnitude of the ionization and acceleration zones upstream shifting as a function of increased background pressure.

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“…The current engineering development unit (EDU2) has demonstrated operation at discharge voltages up to 650 V and discharge powers in excess of 4 kW. 13 When operating at high voltages, the thruster is capable of generating a specific impulse of nearly 2700 s, and when operating at low voltages, it can achieve a thrust-to-power ratio competitive with other state-of-the-art Hall thrusters. Recent testing of the HiVHAc EDU2 took place in Vacuum Facility 5 (VF-5) at GRC in April-May 2013.…”

Section: A High Voltage Hall Accelerator and Testingmentioning

confidence: 99%

Hybrid-PIC modeling of a high-voltage, high-specific-impulse Hall thruster

Smith

Boyd

Kamhawi

et al. 2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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The primary life-limiting mechanism of Hall thrusters is the sputter erosion of the discharge channel walls by high-energy propellant ions. Because of the difficulty involved in characterizing this erosion experimentally, many past efforts have focused on numerical modeling to predict erosion rates and thruster lifespan, but those analyses were limited to Hall thrusters operating in the 200-400 V discharge voltage range. Thrusters operating at higher discharge voltages (V d ≥ 500 V) present an erosion environment that may differ greatly from that of the lower-voltage thrusters modeled in the past. In this work, HPHall, a well-established hybrid-PIC code, is used to simulate NASA's High-Voltage Hall Accelerator (HiVHAc) at discharge voltages of 300, 400, and 500 V as a first step towards modeling the discharge channel erosion. It is found that the model accurately predicts the thruster performance at all operating conditions to within 6%. The model predicts a normalized plasma potential profile that is consistent between all three operating points, with the acceleration zone appearing in the same approximate location. The expected trend of increasing electron temperature with increasing discharge voltage is observed. An analysis of the discharge current oscillations shows that the model predicts oscillations that are much greater in amplitude than those measured experimentally at all operating points, suggesting that the differences in oscillation amplitude are not strongly associated with discharge voltage.

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Performance and Environmental Test Results of the High Voltage Hall Accelerator Engineering Development Unit

Cited by 10 publications

References 19 publications

Effect of Background Pressure on the Plasma Oscillation Characteristics of the HiVHAc Hall Thruster

Effect of Background Pressure on the Plasma Oscillation Characteristics of the HiVHAc Hall Thruster

Investigation of the Effects of Facility Background Pressure on the Performance and Operation of the High Voltage Hall Accelerator

Hybrid-PIC modeling of a high-voltage, high-specific-impulse Hall thruster

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