LIF Erosion Rate Measurements of NEXT Ion Engine for DART Mission

Crofton, Mark W.; Schoeffler, Donner; Young, Jason A.; Patterson, Michael J.; John, Judy St.

doi:10.2514/6.2019-1246

Cited by 4 publications

(4 citation statements)

References 4 publications

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“…where σ cex is the CEX cross section for Xe + -Xe [10], l d is the effective distance over which charge exchange ions are collected, I b is thruster beam current, and n bd is the density of background xenon neutrals in the region where CEX ions are created and collected. This region can be considered to extend from a downstream surface outside the extraction grid system up to the plasma sheath near the screen grid.…”

Section: Relative Doppler and Density Profiles Across The Grid Facementioning

confidence: 99%

“…For the present study, previously described in a conference paper [10], LIF Doppler profiles were obtained across the grid face for several DART operating points, and the effect of flow variation over the envelope possible for DART was evaluated. In addition, relative Doppler profile data were collected at the grid center covering the full range of potential DART operating points, and the effects of elevated background pressure and accelerator grid voltage changes were explored.…”

Section: Introductionmentioning

confidence: 99%

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Erosion Rate Measurements for DART Spacecraft Ion Propulsion System

et al. 2022

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The Double Asteroid Redirection Test (DART) spacecraft was developed to provide the first measurement for orbital deflection of an asteroid upon intentional impact. The NEXT ion engine is part of the mission, on its maiden voyage. As part of the pre-launch risk reduction, erosion characteristics of the extraction grid system were evaluated using laser measurements of sputtered molybdenum atoms over the envelope of potential throttle conditions for the mission. Erosion rate dependence on propellant flow rate as well as relative density and directionality of molybdenum sputter from grid center to edge were measured. Sputtered atoms were found to have average radial velocity directed toward the engine perimeter and increasing with radial distance. The relative contribution of source and facility background gas and other sources of accelerator grid current was examined as well as the influence of several engine operating parameters. Facility background gas was found to influence engine operation more than a wall-mounted pressure gauge and typical assumptions about ingestion would indicate. Far-field flux was estimated over the full angular range based on the near-field relative density and velocity results and relying on quartz crystal microbalance data at one location to fix absolute numbers everywhere. The results substantially deepen knowledge and understanding of the complex grid erosion process of the engine and its lifetime, as grid failure via erosion is the normal life limiter. Study results are also relevant to thruster–spacecraft integration issues such as molybdenum deposition rate on solar cells and other spacecraft surfaces.

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Section: Relative Doppler and Density Profiles Across The Grid Facementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Erosion Rate Measurements for DART Spacecraft Ion Propulsion System

et al. 2022

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“…The results of the Phase 1 diagnostic tests are presented in Refs. [10][11], and will be referenced as necessary within this document.…”

Section: A Test Sequence Definitionmentioning

confidence: 99%

NEXT Ion Propulsion System Risk-Mitigation Tests in Support of the Double Asteroid Redirection Test (DART) Mission

Thomas

Patterson

Crofton

et al. 2019

AIAA Propulsion and Energy 2019 Forum

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Risk mitigation tests have been conducted by the NASA Glenn Research Center and The Aerospace Corporation in support of the DART Mission. The tests focused on NEXT performance characterizations intended to ensure its operations and characteristics are compatible with the DART mission operations, and to assist in the definition of the propulsion system. Tests were performed at the Aerospace Corporation and they involved: flow sensitivity-analyses, steady-state performance characterizations, and measurements of thruster erosion. The tests also involved defining, demonstrating, verifying, and evaluating the start-up sequences and a beam current regulation algorithm consistent with DART mission requirements. It was found that NEXT thruster operations are compatible with the proposed relaxation of flow control ranges for ignition and for steady-state operation.

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“…Hence, the new throttle level DTL28-H-O is DART throttle level 28 with nominal (H) total discharge flow and lean cathode flow (O). The DART test campaign involves multiple measurements of the NEXT, discussed in companion papers [10][11][12][13]. This paper concerns only the angular plume profile and divergence.…”

Section: Introductionmentioning

confidence: 99%

Far Field Plume Distribution and Divergence for NEXT: DART Mission

Young

Matlock

Nakles

et al. 2019

AIAA Scitech 2019 Forum

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In support of the Double Asteroid Redirection Test (DART) mission, laboratory measurements were made on the NEXT ion engine, which will be used for the spacecraft's inspace propulsion [1]. This study revisits a small range of mission-specific 2.7A throttle levels to understand the effect of in-flight flow rate variability, investigate intermediate throttle conditions, and improve measurement methodology. This paper specifically examines the farfield plume divergence and backflow ion flux distribution of the NEXT, while a companion paper examines the charge state distributions.

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LIF Erosion Rate Measurements of NEXT Ion Engine for DART Mission

Cited by 4 publications

References 4 publications

Erosion Rate Measurements for DART Spacecraft Ion Propulsion System

Erosion Rate Measurements for DART Spacecraft Ion Propulsion System

NEXT Ion Propulsion System Risk-Mitigation Tests in Support of the Double Asteroid Redirection Test (DART) Mission

Far Field Plume Distribution and Divergence for NEXT: DART Mission

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