Development and Modelling of a Low Current LaB₆ Heaterless Hollow Cathode

The presented research discusses the design, analysis, and testing of a low current, LaB6 heaterless hollow cathode for space propulsion applications. A heaterless design using LaB6 is chosen to reduce complexity and increase electrical power efficiency and robustness. Argon propellant is used due to its more favorable breakdown voltage characteristics compared to xenon. An original model for the insert region plasma is derived by combining several analyses in literature. This model allows the simultaneous calculation of many plasma and thermal parameters in the cathode using only two completely unobtrusive measurements, and requires several assumptions which are common in hollow cathode research. The design of the cathode and its subsystems are presented in detail. No diagnostics were used in the cathode except direct voltage measurements in the power circuit. A discussion of emitter poisoning and ignition behavior is presented. The cathode is characterized by measuring anode and keeper voltages as a function of anode current and propellant flow rate, with the cathode discharging directly to a flat metal anode. Results are consistent with those obtained by previous investigations of argon hollow cathodes. This data is used with the derived plasma model to calculate the dependence of various parameters on current and flow rate. A discussion of the spot-plume transition behavior is presented. Finally, insights and design improvements are discussed based on the experimental results.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Aerospace Engineering

Department dc:contributor.department

Aerospace and Ocean Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2019

Author dc:creator

• Nikrant, Alex Warner

Chair dc:contributor.committeechair

• Adams, Colin

Committee members dc:contributor.committeemember

• Scales, Wayne A.
• Srinivasan, Bhuvana

• heaterless hollow cathode
• electric propulsion
• plasma dynamics
• plume mode

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

vt_gsexam:22057

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/93959