Numerical Rebuilding of SMART-1 Hall Effect Thruster Plasma Plume

Faraday probes are a common plasma diagnostic used to determine the local ion charge flux of electric propulsion plumes. Standard practices, guidelines, and recommendations are provided for experimental methods and analysis techniques that aim to standardize community practices, to mitigate test environment effects, and to reduce systematic measurement error in order to improve plume predictions in the space environment. The approaches are applicable to time-averaged plasma properties in the near-field and far-field of electric propulsion plumes, with emphasis on Hall effect thrusters and gridded ion thrusters. Considerations for other electric propulsion technologies are provided, including electrosprays, arcjets, and electromagnetic thruster concepts. These test strategies are expected to increase the quality of comparisons between different thrusters and vacuum environments, thereby broadening the applicability of ground-based measurements and enhancing the fidelity for on-orbit predictions and modeling validation.

Section: B Plasma Plume Characterizationmentioning

confidence: 99%

Recommended Practice for Use of Faraday Probes in Electric Propulsion Testing

Brown

Walker

Szabo

et al. 2017

“…The use of hybrid DSMC-particle-in-cell (PIC) codes is well established in the electric propulsion (EP) community to investigate the performance of electric thrusters and the interaction of their plumes with spacecraft [43][44][45][46][47]. The DSMC method [48] is employed to model heavy particle collisions, whereas the PIC method models ion motions in electric fields [49].…”

Section: Direct Simulation Monte Carlo Simulationsmentioning

confidence: 99%

Neutral Gas Expansion in a Cylindrical Helicon Discharge Chamber

Giannelli

Kieckhafer

Walker

2013

The expansion of neutral gas in an open-ended cylindrical chamber into a large vacuum facility is investigated to understand neutral particle density distribution. The cylindrical chamber geometry with a single on-axis gas injection port is representative of a helicon plasma source discharge chamber. The neutral gas pressure profile along the cylinder wall is experimentally measured for argon and xenon mass flow rates of 0-200 sccm, at facility pressures up to 3 × 10 −5 and 3.8 × 10 −5 torr Ar and torr Xe, respectively. The average relative error between the experimentally measured pressure profiles and the numerical results obtained with a direct simulation Monte Carlo code is less than 10%, with the maximum relative error below 30%. The single on-axis injection port into the cylindrical discharge chamber results in a nonuniform neutral particle density distribution in the source due to the recirculation zone generated in the rear of the discharge chamber. This highlights the potential impact of the propellant injection system design on the neutral particle depletion phenomenon in helicon plasma sources.

“…Traditionally, operational background neutral pressure corrections are used as a means to translate ground-based Hall current thruster (HCT) behavior to expected flight operation [1][2][3][4][5][6][7][8][9][10][11]. Recent work on the HCT suggests that pressure considerations may not entirely capture the effect of the vacuum chamber environment on HCT operation [12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…Anomalous thruster behavior was also experienced during the European Space Agency's Small Missions for Advanced Research in Technology-1 (SMART-1) mission using the PPS-1350 HCT. The PPS-1350 HCT showed periods of positive cathode-to-satellite-bus common voltage during times of elevated in-space plasma potential measurements [12,13,19]. The causes of these elevated in-space plasma potential measurements were attributed to exposure of lowvoltage solar panel contacts to the HCT plume [12].…”

Section: Introductionmentioning

confidence: 99%

Electrical Facility Effects on Hall Current Thrusters: Electron Termination Pathway Manipulation

Walker¹,

Langendorf²,

Walker³

et al. 2016

A nonnegligible fraction of the charged particles in the Hall current thruster plume completes the electrical circuit through the conductive wall of a ground-based vacuum test facility. The resultant electrical circuit is different from the electrical circuit completed by the Hall current thruster in the onorbit environment. To understand the electrical circuit created in ground-based testing, this work examines the effect of an electrically biased metal plate, placed in the far-field plume of a Hall current thruster, on the plasma plume characteristics, the Hall current thruster thrust, and the electron termination pathways. An Aerojet Rocketdyne T-140 Hall current thruster is operated at 300 V and 10.3 A on xenon propellant. The operational neutral background pressure is 7.3 × 10 −6 torr, corrected for xenon. Two aluminum plates, one representative of the radial wall of the vacuum chamber and one representative of the axial wall of the vacuum chamber, are placed 2.3 m radially outward from the thruster centerline and 4.3 m axially downstream from the discharge channel exit plane, respectively. At each axial bias plate voltage, measurements of thrust, electrical characteristics of the Hall current thruster, thruster body electrical waveform, and radial-axial plate waveforms are recorded. A Langmuir probe, a Faraday probe, and an emissive probe are placed 1 m downstream of the Hall current thruster exit plane. The cathode-to-ground voltage and plasma potential behavior closely follow the trends observed from in-flight measurements of the Small Missions for Advanced Research in Technology-1 PPS-1350 Hall current thruster. This investigation experimentally quantifies the impact of the varying in-flight plasma plume conditions on Hall current thruster operation in a ground-based vacuum facility.