On the Non-Intrusive Determination of Electron Density in the Sheath of a Spherical Probe
Abstract
A new method of determining probe/antenna plasma sheath parameters has been developed. For low neutral pressure environments in the absence of a magnetic field, the method provides these quantities from a probe/antenna surface through the sheath, pre-sheath, and into the bulk plasma. For high pressure environments, where conventional resonances are strongly damped, it can determine bulk plasma density. The paper cites commonly used methods of finding electron density/temperatue and points out the inadequacy of each to make sheath measurements in the general case. The primary advantage of the method lies in the fact that a non-perturbative rf signal is applied to the probe/antenna for the determination and this makes the measurement independent of complicating influences such as secondary electron emission, surface conditions, and ion mass. Because of this, the ac impedance depends on frequency but not on the dc voltage unlike a typical Langmuir probe. In this paper, we concentrate on the low pressure regime.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 20, 2007
- Accession Number
- ADA466367
Entities
People
- D. D. Blackwell
- D. N. Walker
- Richard F. Fernsler
- W. E. Amatucci
Organizations
- United States Naval Research Laboratory