Electrical Facility Effects on Faraday Probe Measurements

Impact of Propellant Species on Hall Effect Thruster Electrical Facility Effects

“…Although the current collection by the facility walls is controlled by the wall sheath and does not impact quasi-neutrality in the plume, this alternate electron recombination pathway is an artificial effect introduced by the presence of the vacuum facility that is expected to be absent on orbit. Furthermore, previous work has confirmed that the presence of this alternate pathway can alter processes dependent on the electron path through the plasma, such as cathode coupling and plasma reactance, [26][27][28][29].…”

“…Figure 1 shows the physical location of the plates with respect to the T-40 HET. Identical plates have been used in previous studies of electrical facility effects [26][27][28][29]. The surface area of the plates represents approximately 2% of the total facility wall area.…”

“…Because the focus of this work is the electrical coupling between the conductive facility walls and the HET plume, it is useful to examine how the plume ion current density profile changes between operation with xenon and krypton before presenting the data collected using the test plates [29]. The ion current density profiles of the T-40 HET for operation with xenon and krypton are shown in Fig.…”

“…HET test facility walls are also almost ubiquitously metallic and, as such, have finite electrical conductivity. Recent work has indicated that the electrical conductivity of the chamber plays a significant role in the HETelectrical circuit, and consequently represents an electrical facility effect [23,[26][27][28][29]. Specifically, this work has shown that the facility walls collect a significant fraction of the discharge current, thereby acting as an alternate recombination site for plume ions and electrons that have not undergone recombination before reaching the facility walls.…”

“…The majority of the archival work on facility effects (both electrical and pressure) has been conducted using HETs operating with xenon propellant [26][27][28][29]. Although xenon is the most common choice for HET propellant, the scarce quantity and increasing demand for xenon has sparked interest in other potential HET propellant options.…”