Anomalous Ion Heating and Pole Erosion in the 12.5-kW Hall Effect Rocket with Magnetic Shielding (HERMeS)

Ortega, Alejandro López; Mikellides, Ioannis G.; Chaplin, Vernon H.; Huang, Wensheng; Frieman, Jason D.

doi:10.2514/6.2020-3620

Cited by 23 publications

(20 citation statements)

References 17 publications

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“…We present a numerical investigation of the effects of vacuum facility backpressure on the performance and life of Hall thrusters using the SPT-140 as a benchmark. We employ Hall2De [16,17], a 2D axisymmetric (r-z) scientific code that has been used in the past to investigate performance [18][19][20][21] and erosion rates [18][19][20][21][22][23][24] of multiple Hall thrusters including the H6 [18,20,21,24], HERMeS [23], and the XR-5 (formerly, the BPT-4000) [19,22]. Hall2De was also employed in the development and demonstration of magnetic shielding [19].…”

Section: Introductionmentioning

confidence: 99%

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: 99%

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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“…Mikellides et al [23][24][25] have developed Hall2De, a fullfluid axisymmetric code for HETs, which has been useful in analyzing the plasma response in magnetically shielded HETs such as the Aerojet Rocketdyne XR-5 (previously BPT-4000), or the HERMeS thruster [20,26]. Hall2De implements a fully 2D treatment of the electron fluid equations on a magnetic field aligned mesh (MFAM or magnetic mesh for short) and is applicable to any axisymmetric magnetic topology.…”

Section: Introductionmentioning

confidence: 99%

Numerical treatment of a magnetized electron fluid model within an electromagnetic plasma thruster simulation code

Zhou¹,

Perez-Grande²,

Fajardo³

et al. 2019

Plasma Sources Sci. Technol.

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Plasma discharges in electromagnetic thrusters often operate with weakly-collisional, magnetized electrons. Macroscopic models of electrons provide affordable simulation times but require to be solved in magnetically aligned meshes so that large numerical diffusion does not ruin the solution. This works discusses suitable numerical schemes to solve the axisymmetric equations for the electric current continuity and the tensorial Ohm's law in such meshes, when bounded by the thruster cylindrical or annular chamber. A finite volume method is appropriate for the current continuity equation, even when meshes present singular magnetic points. Finite differences and weighted least squares methods are compared for the Ohm's law. The last method is more prone to producing numerical diffusion and should be used only in the boundary cells and requires a special formulation in the boundary faces. In addition, the use of the thermalized potential is suggested for an accurate computation of parallel electron current densities for very high conductivity. The numerical algorithms are tested in a hybrid (particle/fluid) simulation code of a helicon plasma thruster, for different magnetic fields, mesh refinement, and plume lengths. The different contributions to the electric current density are assessed and the formation and relevance of longitudinal electric current loops is discussed.1

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“…However, these same models predict that this trend should reverse for operation at 300 V, and, therefore, that the measured erosion rates should have decreased with increased magnetic field strength due to the upstream shift in acceleration zone (Ref. 30). The cause for this discrepancy is not presently known, and, as such, further investigation may be warranted.…”

Section: Ifpc Wearmentioning

confidence: 97%

Long Duration Wear Test of the NASA HERMeS Hall Thruster

Frieman

Kamhawi

Williams

et al. 2018

2018 Joint Propulsion Conference

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Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientifi c and Technical Information (STI) Program plays a key part in helping NASA maintain this important role. The NASA STI Program operates under the auspices of the Agency Chief Information Offi cer. It collects, organizes, provides for archiving, and disseminates NASA's STI. The NASA STI Program provides access to the NASA Technical Report Server-Registered (NTRS Reg) and NASA Technical Report Server-Public (NTRS) thus providing one of the largest collections of aeronautical and space science STI in the world. Results are published in both non-NASA channels and by NASA in the NASA STI Report Series, which includes the following report types: • TECHNICAL PUBLICATION. Reports of completed research or a major signifi cant phase of research that present the results of NASA programs and include extensive data or theoretical analysis. Includes compilations of signifi cant scientifi c and technical data and information deemed to be of continuing reference value. NASA counter-part of peer-reviewed formal professional papers, but has less stringent limitations on manuscript length and extent of graphic presentations.

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Anomalous Ion Heating and Pole Erosion in the 12.5-kW Hall Effect Rocket with Magnetic Shielding (HERMeS)

Cited by 23 publications

References 17 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

Numerical treatment of a magnetized electron fluid model within an electromagnetic plasma thruster simulation code

Long Duration Wear Test of the NASA HERMeS Hall Thruster

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