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Open AccessArticle

On the Spatial Uniformity of the Degree of Ionization in a Helium ECR Plasma Produced under a Simple Cusp Field

Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University, Kyoto 615-8540, Japan
Bunkokeiki Co., Ltd., Hachioji, Tokyo 192-0033, Japan
Author to whom correspondence should be addressed.
Atoms 2019, 7(2), 49;
Received: 24 March 2019 / Revised: 10 May 2019 / Accepted: 13 May 2019 / Published: 17 May 2019
(This article belongs to the Special Issue Plasma Spectroscopy in the Presence of Magnetic Fields)
PDF [1251 KB, uploaded 17 May 2019]


Production of a plasma that has a large degree of ionization (DOI), volume, and spatial and temporal uniformities is a challenge for the improvement of the performance of plasma-based vapor deposition processes. As a potential candidate for the discharge, we investigate plasma parameters arising in helium electron cyclotron resonance (ECR) discharges due to a simple cusp field. Two-dimensional distributions of helium atom emission-line intensities were measured using spectroscopy with multiple viewing chords and then de-convoluted by Abel inversion. The local plasma parameters, including the atomic density, were evaluated using collisional-radiative model analysis. The DOI calculated from the electron and atomic densities reached up to 35% and, in most of the region inside the ECR surface, it was more than 10%. View Full-Text
Keywords: spectroscopy; diagnostics; low temperature plasma; ECR spectroscopy; diagnostics; low temperature plasma; ECR

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Ueda, A.; Shikama, T.; Iida, Y.; Hasuo, M. On the Spatial Uniformity of the Degree of Ionization in a Helium ECR Plasma Produced under a Simple Cusp Field. Atoms 2019, 7, 49.

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