Investigation of the RF efficiency of inductively coupled hydrogen plasmas at 1MHz

D. Rauner, S. Mattei, S. Briefi, U. Fantz, A. Hatayama, J. Lettry, K. Nishida, M. Q. Tran

研究成果: Conference contribution

1 被引用数 (Scopus)

抄録

The power requirements of RF heated sources for negative hydrogen ions in fusion are substantial, which poses strong demands on the generators and components of the RF circuit. Consequently, an increase of the RF coupling efficiency would be highly beneficial. Fundamental investigations of the RF efficiency in inductively coupled hydrogen and deuterium discharges in cylindrical symmetry are conducted at the lab experiment CHARLIE. The experiment is equipped with several diagnostics including optical emission spectroscopy and a movable floating double probe to monitor the plasma parameters. The presented investigations are performed in hydrogen at a varying pressure between 0.3 and 10 Pa, utilizing a conventional helical ICP coil driven at a frequency of 1MHz and a fixed power of 520W for plasma generation. The coupling efficiency is strongly affected by the variation in pressure, reaching up to 85% between 1 and 3 Pa while dropping down to only 50% at 0.3 Pa, which is the relevant operating pressure for negative hydrogen ion sources for fusion. Due to the lower power coupling, also the measured electron density at 0.3 Pa is only 5 · 1016 m-3, while it reaches up to 2.5 · 1017 m-3 with increasing coupling efficiency. In order to gain information on the spatially resolved aspects of RF coupling and plasma heating which are not diagnostically accessible, first simulations of the discharge by an electromagnetic Particle-In-Cell Monte Carlo collision method have been conducted and are compared to the measurement data. At 1 Pa, the simulated data corresponds well to the results of both axially resolved probe measurements and radially resolved emission profiles obtained via OES. Thereby, information regarding the radial distribution of the electron density and mean energy is provided, revealing a radial distribution of the electron density which is well described by a Bessel profile.

本文言語English
ホスト出版物のタイトル5th International Symposium on Negative Ions, Beams and Sources, NIBS 2016
編集者Dan Faircloth
出版社American Institute of Physics Inc.
ISBN(電子版)9780735415492
DOI
出版ステータスPublished - 2017 8 9
イベント5th International Symposium on Negative Ions, Beams and Sources, NIBS 2016 - Oxford, United Kingdom
継続期間: 2016 9 122016 9 16

出版物シリーズ

名前AIP Conference Proceedings
1869
ISSN(印刷版)0094-243X
ISSN(電子版)1551-7616

Other

Other5th International Symposium on Negative Ions, Beams and Sources, NIBS 2016
国/地域United Kingdom
CityOxford
Period16/9/1216/9/16

ASJC Scopus subject areas

  • 物理学および天文学(全般)

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