Optimization, Test and Diagnostics of Miniaturized Hall Thrusters

Summary

Here, we present a protocol to test and optimize space propulsion systems based on miniaturized Hall-type thrusters.

Abstract

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without attendance and adjustment. Thermochemical thrusters which utilize thermodynamic properties of gases as a means of acceleration have physical limitations on their exhaust gas velocity, resulting in low efficiency. Moreover, these engines demonstrate extremely low efficiency at small thrusts and may be unsuitable for continuously operating systems which provide real-time adaptive control of the spacecraft orientation, velocity and position. In contrast, electric propulsion systems which use electromagnetic fields to accelerate ionized gases (i.e., plasmas) do not have any physical limitation in terms of exhaust velocity, allowing virtually any mass efficiency and specific impulse. Low-thrust Hall thrusters have a lifetime of several thousand hours. Their discharge voltage ranges between 100 and 300 V, operating at a nominal power of <1 kW. They vary from 20 to 100 mm in size. Large Hall thrusters can provide fractions of millinewton of thrust. Over the past few decades, there has been an increasing interest in small mass, low power, and high efficiency propulsion systems to drive satellites of 50-200 kg. In this work, we will demonstrate how to build, test, and optimize a small (30 mm) Hall thruster capable of propelling a small satellite weighing about 50 kg. We will show the thruster operating in a large space environment simulator, and describe how thrust is measured and electric parameters, including plasma characteristics, are collected and processed to assess key thruster parameters. We will also demonstrate how the thruster is optimized to make it one of the most efficient small thrusters ever built. We will also address challenges and opportunities presented by new thruster materials.

Introduction

Renewed interest in the space industry has in part been catalyzed by highly efficient electric propulsion systems that deliver enhanced mission capabilities at increasingly reduced launch costs^1,2,3. Many different types of space electric propulsion devices have recently been proposed and tested^4,5,6,7,8 supported by the present-day interest in space exploration^9,

Protocol

Here we present the protocols for the thrust calibration procedure and performance evaluation, independent thrust verification via null measurement and plume profilometry through spatial in situ data sensing.

1. Thrust calibration procedure and thrust performance evaluation

1. Ensure that all components are installed in the chamber as shown in Figure 5.
2. Test the connectivity of the diagnostic tools externally before sealing the chamber.<.......

Discussion

Typical Hall-type thrusters⁴⁴ are relatively simple, cheap and highly efficient devices that could accelerate an ion flux to the velocities of several tens of km/s, providing thrust required for accelerating satellites and spacecraft, as well as for maneuvering, orientation, position and attitude control, and de-orbiting at the end of their operation service life. Application of Hall thrusters on satellites and other orbital payloads enhance mission lifetime, allow orbital transfer and formation/c.......

Materials

Name	Company	Catalog Number	Comments
Arduino Microcontroller	Arduino	Arduino Uno Rev 3
Bluetooth communication device	SG Botic	WIR-02471
Cryogenic Pump	ULVAC	CRYO-U12HLE
Digital Oscilloscope	Yokogawa	DLM 2054
Dry Pump	Agilent	Triscroll-600
High resolution laser displacement sensor	Micro-Epsilon	optoNCDT ILD-1420-50
Mass Flow Controller	MKS	MKS M100B
Optical Emission Spectrometer	Avantes	AvaSpec-ULS2048XL-EVO
Servo Motor	Tower Pro	Servo Motor SG90
Stepper Motor	Oriental Motor	PKP213D05A
Turbomolecular Pump	Pfeiffer	ATH-500M