Far-Field Plume Characterization of a 100-W Class Hall Thruster

Thibault Hallouin,Stéphane Mazouffre

doi:10.3390/aerospace7050058

Thibault Hallouin, Stéphane Mazouffre

Open Access

https://doi.org/10.3390/aerospace7050058

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Abstract

The 100 W-class ISCT100-v2 Hall Thruster (HT) has been characterized in terms of far-field plume properties. By means of a Faraday Cup and a Retarding Potential Analyzer, both the ion current density and the ion energy distribution function have been measured over a 180 ∘ circular arc for different operating points. Measurements are compared to far-field plume characterizations performed with higher power Hall thrusters. The ion current density profiles remain unchanged whatever the HT input power, although an asymptotic limit is observed in the core of the plume at high discharge voltages and anode mass flow rates. In like manner, the ion energy distribution functions reveal that most of the beam energy is concentrated in the core of the plume [ − 40 ∘ ; 40 ∘ ] . Moreover, the fraction of low energy ion populations increases at large angles, owing to charge exchange and elastic collisions. Distinct plume regions are identified; they remain similar to the one described for high-power HTs. An efficiency analysis is also performed in terms of current utilization, mass utilization, and voltage utilization. The anode efficiency appears to be essentially affected by a low voltage utilization, the latter originating from the large surface-to-volume ratio inherent to low-power HTs. Experimental results also show that the background pressure clearly affects the plume structure and content.

Highlights

Over the last decade, the satellite miniaturization has opened up a new space market.Technologically simple, inexpensive, and flexible, nano- and micro-satellites (1–200 kg) are well suited for various low Earth orbit missions, communication, science, and observation [1,2]
The fraction of low energy ion populations increases at large angles, owing to charge exchange and elastic collisions
We have measured ion current density and ion energy in the far-field plume of the 100 W-class ISCT100-v2 Hall Thruster (HT), by means of a Faraday Cup and a 4-grid Retarding Potential Analyzer (RPA), respectively. The impact of both anode mass flow rate and discharge voltage has been investigated and compared with far-field plume diagnostics of high-power HTs. It appears that the current density profiles remain similar whatever the HT input power, even though the 100 W-class HT is more sensitive to operating parameters

Summary

Introduction

The satellite miniaturization has opened up a new space market. Simple, inexpensive, and flexible, nano- and micro-satellites (1–200 kg) are well suited for various low Earth orbit missions, communication, science, and observation [1,2]. Propulsion systems have understandably adapted to this new market, through miniaturization and reduction of operating power. Compared to its chemical counterpart, electric propulsion is appropriated to challenges and needs of the micro-satellite market. In addition to a long operation time, one of the major advantages of electric propulsion is a high attainable exhaust velocity [1]. As a matter of fact, liquid or solid chemical thrusters are limited by the energy per unit of mass stored in the propellant.

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