Ph.D. Defense

Chhavi

(Advisor:  Professor Mitchell L.R. Walker)

"Investigation of impact of Azimuthal magnetic field gradient on Performance characteristics and stability of Hall effect Thrusters"

Monday, July 15

9:00 a.m.

Montgomery Knight 325

Abstract

HETs are intended to function with a uniform axisymmetric magnetic field. On the other hand, imperfections in the manufacturing process and electrical shorts that occur during operation might lead to the formation of non-uniformities in the channel. Azimuthal magnetic field gradients are one type of non-uniformity that can arise in the magnetic field. As a result, it is imperative to comprehend the impact of the non-uniform azimuthal magnetic field gradient on the thruster's performance. This thesis aims to quantify the alteration in thruster performance parameters, including efficiency, stability, and thrust, as a result of introducing an azimuthal magnetic field gradient. In order to achieve this, the thruster is modified to enable independent control of the outer magnetic circuit, which in turn enables the current to be adjusted. A three-dimensional sweep probe instrument was constructed to show how the azimuthal magnetic field gradient affects the thrust vector direction. The research results indicate that the azimuthal magnetic field gradient has the most significant impact on the thruster's stability, leading to increased instability during operation. The thrust and efficiency decrease as the gradient increases, with the thrust experiencing the most negligible impact. The introduction of the gradient is indicative of the thrust vector's deviation from the centerline, which leads to a three-dimensional shift in the thrust vector's position. The research offers a physics-based model to explain the observed trends in thruster performance that result from changes in the plasma parameters.

Committee

• Prof. Mitchell L.R. Walker–  School of Aerospace Engineering (advisor)

• Prof. Wenting Sun – School of Aerospace Engineering 

• Prof. Sedina Tsikata – School of Aerospace Engineering

• Prof. Lukas Graber – School of Electrical and Computer Engineering 

• Dr. Kunning Xu  – Mechanical and Aerospace Engineering at University of Alabama, Huntsville