Date of Defense

4-16-2024

Date of Graduation

4-2024

Department

Mechanical and Aerospace Engineering

First Advisor

Kristina Lemmer

Second Advisor

Nicholas Taylor

Abstract

Ground testing of electric propulsion (EP) devices occurs inside vacuum chambers and is monitored using high-frequency and low-frequency telemetry systems. These systems provide critical operational information about the device’s performance by monitoring values such as voltage, current, gas flow rates, and chamber pressures. Ground facility telemetry systems can operate as integrated control and safety architecture while testing EP devices. EP testing at Western Michigan University (WMU) is located within the Aerospace Laboratory for Plasma Experiments (ALPE). The Cold plasma Experimental Research Station (CEReS) is outfitted with CTI-250F and CTI-10 cryogenic pumps for a combined pumping capacity of 5,200L/s-air. CEReS facilitates the testing of various EP devices, including a 200W Hall effect thruster (HET), a 20A class hollow cathode, and a low current heaterless hollow cathode. These devices have diverse voltage and current requirements, which require necessary protective circuitry for their operation. For instance, the 200W HET utilizes an integrated discharge filter due to the oscillatory nature of HETs, and the heaterless hollow cathode requires ballast resistors and protective diodes. Therefore, an agnostic telemetry and remote-control system, capable of variable and selectable circuitry, was designed, allowing for seamless functionality while accounting for the variations between thruster devices.

The CEReS vacuum chamber is outfitted with seven power supplies that vary in power output. The telemetry system was designed to monitor these outputs, specific to each power supply, using integrated circuitry. Installed voltage dividers and shunt resistors provide time-averaged measurements, and Pearson coils and high-voltage probes are used for time-resolved measurements. The voltage dividers utilize custom-built printed circuit boards (PCB) with specific resisitor values, dependent on each power supply, and fuses for amperage transients to provide voltage measurements. A trade study was conducted on four current sensor methodologies: custom-built CQ330E, FluxGate, Shunt-based, and Hall effect. These methodologies were analyzed based upon cost, accuracy, and bandwidth per current measurements during simulated load and H6 hollow cathode tests. The custom-built CQ330E PCBs utilize a quantum well, ultrathin film, Indium Arsenide Hall sensor for 2.4% accuracy during maximum 20.5A sensing. The Verivolt IsoBlock I-FG-1c FluxGate sensors measure current through inductance change in the saturable core with high-quality, 0.2% accuracy measurements. The Shunt-based Verivolt IsoBlock I-ST-1c measures current over a high-performance, low impedance resistor with 3-way Galvanic isolation at 0.2% accuracy. The Hall effect Vektrex VCS40 measures current by a produced voltage through a magnetic field with 40A range at 0.5% accuracy. These diagnostic devices are housed inside plexiglass Breakout Boxes (BoB) and mounted into the power rack behind the power supplies. The measurements are collected using National Instruments’ USB-6229 data acquisition system and saved using the designed Telemetry LabVIEW program. This LabVIEW program catalogs all parameters and measurements based upon EP device selection through the telemetry, control, and configure windows. Digital remote-control features for the ALICAT mass flow meters and Instrutech B-RAX 3200 pressure monitor are integrated within this program alongside current and voltage measurements. Thus, the telemetry and remote-control systems are designed for modularity and agnostic capabilities through the integrated hardware and software.

Comments

Co-authored with:

Douglas Adams

Adam Tuckey

Access Setting

Honors Thesis-Open Access

Additional Files
Presentation.pdf (3313 kB)
Defense Presentation
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