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

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

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.

Original languageEnglish
Title of host publication5th International Symposium on Negative Ions, Beams and Sources, NIBS 2016
PublisherAmerican Institute of Physics Inc.
Volume1869
ISBN (Electronic)9780735415492
DOIs
Publication statusPublished - 2017 Aug 9
Event5th International Symposium on Negative Ions, Beams and Sources, NIBS 2016 - Oxford, United Kingdom
Duration: 2016 Sep 122016 Sep 16

Other

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

Fingerprint

hydrogen plasma
hydrogen ions
radial distribution
negative ions
fusion
plasma generators
plasma heating
probes
optical emission spectroscopy
hydrogen
profiles
ion sources
floating
deuterium
coils
generators
electromagnetism
requirements
heating
collisions

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Rauner, D., Mattei, S., Briefi, S., Fantz, U., Hatayama, A., Lettry, J., ... Tran, M. Q. (2017). Investigation of the RF efficiency of inductively coupled hydrogen plasmas at 1MHz. In 5th International Symposium on Negative Ions, Beams and Sources, NIBS 2016 (Vol. 1869). [030035] American Institute of Physics Inc.. https://doi.org/10.1063/1.4995755

Investigation of the RF efficiency of inductively coupled hydrogen plasmas at 1MHz. / Rauner, D.; Mattei, S.; Briefi, S.; Fantz, U.; Hatayama, Akiyoshi; Lettry, J.; Nishida, K.; Tran, M. Q.

5th International Symposium on Negative Ions, Beams and Sources, NIBS 2016. Vol. 1869 American Institute of Physics Inc., 2017. 030035.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Rauner, D, Mattei, S, Briefi, S, Fantz, U, Hatayama, A, Lettry, J, Nishida, K & Tran, MQ 2017, Investigation of the RF efficiency of inductively coupled hydrogen plasmas at 1MHz. in 5th International Symposium on Negative Ions, Beams and Sources, NIBS 2016. vol. 1869, 030035, American Institute of Physics Inc., 5th International Symposium on Negative Ions, Beams and Sources, NIBS 2016, Oxford, United Kingdom, 16/9/12. https://doi.org/10.1063/1.4995755
Rauner D, Mattei S, Briefi S, Fantz U, Hatayama A, Lettry J et al. Investigation of the RF efficiency of inductively coupled hydrogen plasmas at 1MHz. In 5th International Symposium on Negative Ions, Beams and Sources, NIBS 2016. Vol. 1869. American Institute of Physics Inc. 2017. 030035 https://doi.org/10.1063/1.4995755
Rauner, D. ; Mattei, S. ; Briefi, S. ; Fantz, U. ; Hatayama, Akiyoshi ; Lettry, J. ; Nishida, K. ; Tran, M. Q. / Investigation of the RF efficiency of inductively coupled hydrogen plasmas at 1MHz. 5th International Symposium on Negative Ions, Beams and Sources, NIBS 2016. Vol. 1869 American Institute of Physics Inc., 2017.
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