Recommended Practice for Use of Faraday Probes in Electric Propulsion Testing

Abstract

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.

Background Pressure Effects on the Performance of a 20 kW Magnetically Shielded Hall Thruster Operating in Various Configurations

“…The was found to be independent on the pump configuration. For the plume divergence , even if the effect of the higher background pressure was noticed by a local increase of the current density due to the charge exchange (CEX) collisions at the wings of the plume [47], the measured divergence angle did not significantly change between the seven and five panel operations.…”

“…The design of all the Faraday probes was the same of the one indicated as probe D in [46] (Centro Spazio/ALTA). In the calculation of the beam current and plume divergence , the geometric correction factors (here summarized with ) of [47] were used. Considering the coordinate system introduced in Figure 4, the beam current was thus calculated according to the following integral:…”

Direct Thrust Measurement of an Electron Cyclotron Resonance Plasma Thruster

“…18, which correspond to the uncertainties of the probe measurement, have been determined according to the recommended practice for the use of Faraday probes [36]. They have been calculated using eq.…”

Liquid-Fed Pulsed Plasma Thruster with Low-Energy Surface Flashover Igniter for Propelling Nanosatellites

“…The total ion current generated by the LF-PPT was measured using a large-area plane Langmuir probe (or unguarded Faraday probe) with a diameter of 16.5 cm [14,15,16,17]. The current collected by the probe was directly measured by a Bergoz fast current transformer as shown in Figure 2…”