Session: ASME Undergraduate Student Design Expo

Paper Number: 167005

An Analysis of Hall Thruster Performance Through an Undergraduate Lens 

High fuel requirements for interstellar travel represent a substantial obstacle to advancements in space exploration. This is especially the case for long-term missions where spacecraft have no opportunities to refuel. The Hall Effect Thruster (HET) represents a viable solution to this issue. The HET is an electric propulsion system that ionizes and accelerates noble gases to generate thrust. HETs improve satellite efficiency as they do not require the mechanisms traditionally used to maintain propellant temperature and pressure, utilizing less fuel over long periods of time. Beginning in the early 1950s, Hall Effect Thrusters provided an alternative to traditional methods of flammable, liquid propulsion. As the Space Age progressed, the usage of electric propulsion was key to reducing weight on satellites and increasing the longevity of missions. This project seeks to compare simulated Hall Thruster performance to experimental results, specifically regarding thrust, specific impulse (ISP), discharge current, and magnetic flux density at different discharge channel depths. In addition, this project seeks to compare its results, as one of the first successful undergraduate HETs, to other attempted engines. These comparisons assist in describing unexpected operating conditions and flaws in performance modeling. Through these comparisons we present an analysis of our results. Magnetic flux density was measured with a Gauss probe and compared to simulated values by employing 2D simulations of the magnetic field and flux. The values we achieved in these simulations suggest that the magnetic circuit will generate a magnetic field similar to HETs in the same size range as our thruster. These simulations allow us to explore the limitations of digitally-generated HET in order to accurately predict performance. Additionally, we note within a HET there is a buildup of negative charge that occurs within the system. By implementing a thermionic emitter, we counteracted this net buildup charge. By producing an emission current density of 1.14 A/cm2 with an operating temperature of 1900K, the electrons produced by this emitter deionize the propellant, thereby stabilizing the entire engine design. Furthermore, discharge current was measured using an oscilloscope to investigate breathing mode oscillations within the thruster. Experimental thrust values were measured using a plate-pendulum system located in the front of the thruster through which thrust can be measured based on deflection angle. This was in turn compared to the original design parameters of the thruster, in order to calculate the difference between intended and realistic thruster performance. Model validation will improve the approximation of performance for future electric propulsion designs, eliminating the need for costly trial and error. It is with these design results that we complete manufacturing of the HET, with the expectation that a hotfire will successfully allow for us to measure its parameters, including duration of thrust, ISP and others. Ultimately we present our findings here with the intent of serving as a goalpost for future undergraduate endeavors related to HETs.

Presenting Author: Max Neitzke Purdue University

Presenting Author Biography: I am a sophomore in Applied Physics at Purdue University. This poster is being presented through my club at Purdue entitled Purdue Undergraduate Rocket Propulsion Lab [PURPL]. I am currently one of two co-presidents, we have 5 different propulsion projects we oversee which provide students with a chance practicing hands-on applications of engineering. Outside of this work, I study supernovae spectroscopy with a lab at Purdue. I hope to go to graduate school in a few years to pursue my PhD in this field.

Authors:

Madeline Taylor Purdue University
Rowan Murphy Purdue University
Max Neitzke Purdue University
Peyton Barton Purdue
Chris Stemporzewski Purdue
Suhani Pothireddy Purdue