Characterization of Inert Gas Plasma Thrusters
Abstract
The efficiency of modern Hall thrusters is impacted by the ability to maintain a high ratio of the ion to electron current density, J(sub i)/J(sub e), at the exit of the acceleration channel. In principal, there is no limit to this ratio, since the electrons that are necessary to maintain the current balance at the anode can be generated within the ionization zone upstream of the channel exit. However, in practice, this metric of performance in a typical Hall thruster can range from ^ 1 - 10. This is in part due to the loss of electrons and ions through recombination reactions on the channel wall, and also due to the anomalous migration of electrons from the exit plane through the region of strong magnetic fields. It is believed that this poor confinement of electrons is in part due to turbulent fluctuations in plasma properties, which give rise Bohm-like electron transport in a direction orthogonal to the applied magnetic field. The Stanford Research was aimed at understanding this transport, and any affects that wall scattering may have on also enhancing electron current flow within the discharge channel. The broader long-term objective is to develop passive and/or active control strategies to enhance or suppress electron flow in regions of the channel where such actuation is desirable. Feedback-controlled actuation methods to reduce plasma fluctuations where only marginally successful back in the mid 70's in early versions of Hall thrusters 1,2. Using modern diagnostic and characterization strategies to obtain an improved understanding of the role that fluctuations and wall scattering plays in electron transport, it is anticipated that we can design more effective control and actuation strategies.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 07, 2001
- Accession Number
- ADA388079
Entities
People
- Mark Cappelli
Organizations
- Stanford University