Examination of a Hall Thruster Start Transient
Abstract
We discuss the appearance of an anode current transient which persists a maximum of 500 seconds and results in a 50% increase in the anode current during initial start-up following exposure to ambient laboratory conditions. The anode current transient is characterized by 18 kHz main discharge on/off behavior. This contrasts with the steady state behavior of a strong DC component overlaid with a low amplitude 25 kHz component. Conduction through the radial magnetic field appears to be modified during the transient period. The main discharge chamber is determined to be the source of this behavior. The anode current transient appears to be a result of water absorption on the surface layer of the boron nitride insulator. We speculate as to the connection between the absorption of water and the anode current transient. The modification of the secondary electron emission coefficient could affect near wall conductivity and produce the measured effects. The introduction of hydrogen from dissociated water could also produce these enhanced oscillations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 13, 2002
- Accession Number
- ADA408543
Entities
People
- B. Pote
- W. A. Hargus Jr.
Organizations
- Air Force Research Laboratory