AVS 52nd International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP22
Electron Density Measurements with Surface Wave Probes in Magnetized Plasmas

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Plasma Science and Technology Poster Session
Presenter: K. Nakamura, Chubu University, Japan
Authors: K. Nakamura, Chubu University, Japan
S. Yajima, Nagoya University, Japan
H. Sugai, Nagoya University, Japan
Correspondent: Click to Email
In this paper, the surface wave (SW) probe for measuring electron densities@footnote 1@ was applied to magnetized plasmas, and the characteristics of the SW probe located in parallel to the field were examined experimentally and theoretically under a condition of low plasma density and/or high magnetic field corresponding to magnetron discharges. The experiments were made in inductively-coupled argon magnetized plasmas, and absorption frequencies of the SW probe measured by a network analyzer was examined as a function of the plasma frequency measured by the Langmuir probe. At the low magnetic field, the absorption frequency decreased with a decrease in the plasma, thus proportional to the plasma frequency. However, as the magnetic field increased, a saturation of the decrease in the absorption frequency was observed, especially for the low plasma frequency. The saturated absorption frequency were very close to the electron cyclotron frequency obtained from the applied magnetic field, suggesting that the absorption frequency was seriously affected by the magnetic field under the low density conditions. Actually, plotting absorption frequency @omega@ over cyclotron frequency @omega@@sub c@ as a function of plasma frequency @omega@@sub p@ normalized by @omega@@sub c@, its slope approached to zero with an decrease in @omega@@sub p@/ @omega@@sub c@. This result suggested that the absorption frequency became independent of the plasma frequency as a decrease in @omega@@sub p@/ @omega@@sub c@ and that the density measurements was difficult under the low density and/or high field conditions of @omega@@sub p@/ @omega@@sub c@~0.5. Such a saturation was improved by optimization of dimensions of the probe. Especially, reducing the diameters of the rod antenna and the quartz cover tube of the probe was effective and extended measurable range of @omega@@sub p@/ @omega@@sub c@. @FootnoteText@ @footnote 1@ H. Kokura et al: Jpn. J. Appl. Phys 38 (1999) 5262.