Experimental Assessment of Double Langmuir Probe Analysis Techniques in a Hall Thruster Plume
Abstract
A recent theoretical study of double Langmuir probes led to development of improved analytical techniques that account for probe electrode sheath expansion in a low-temperature plasma environment. The proposed technique is based on analytical curve fitting to Laframboise's results, which enables double probe measurement of electron temperature and plasma density over a wide range of densities without advance knowledge of the probe radius relative to Debye length. In this investigation, the method was evaluated by comparing plasma properties from three double Langmuir probes of varying electrode diameter. Far-field measurements of a Hall thruster plume were conducted with each probe at two facility background pressures. Plasma characteristics were calculated using the proposed analytical technique, and compared to orbital motion limited and thin-sheath analyses in regions of the plume where these methods are valid. Results revealed equivalent plasma properties from each double probe geometry when using the proposed double probe analysis methodology, indicating the electrode sheath expansion is accounted for. Calculated plasma densities and electron temperatures were consistent with standard analysis techniques. These findings support the proposed double probe analysis method for examination of plasma properties over a wide span of the far-field plume using a fixed Langmuir probe design and a single analysis technique.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 25, 2012
- Accession Number
- ADA580308
Entities
People
- B. E. Beal
- D. L. Brown
- J. M. Blakely
Organizations
- Air Force Research Laboratory