Date of Award

8-2018

Degree Name

Master of Science in Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Dr. Kristina Lemmer

Second Advisor

Dr. Jennifer Hudson

Third Advisor

Dr. Mike McDonald

Keywords

Hollow cathode, novel insert, cermet, barium oxide, lanthanum hexaboride

Access Setting

Masters Thesis-Open Access

Abstract

This thesis compares two different hollow cathode assemblies (HCA) using three different insert materials. NASA’s Jet Propulsion Laboratory (JPL) provided the H6 HCA and the Lanthanum Hexaboride (LaB6) insert. A barium oxide (BaO) insert was purchased from Ebeam and used with the H6 HCA. The novel Cermet material was purchased from Plasma Controls, LLC and the HCA was based on the JPL H6 HCA. Plasma properties in the external region of all three inserts and the internal region of the LaB6 were determine using two separate Langmuir probes. Various operating points were tested at a combination of flow rates and keeper and discharge currents. The ion number densities of both the LaB6 and BaO were compared with those measured in the plume of the Cermet cathode. It was determined that the Cermet produced higher ion number densities than the similarly sized LaB6, but only produced similar ion number densities between 25 – 40 mm downstream of the orifice plate for the BaO insert. Using the cathode internal probing box internal and external plasma properties of the LaB6 was analyzed. The trend of the ion density showed good agreement with literature. Telemetry data at stable operating points are presented.

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