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Poster communications

Spectroscopic measurements of hydrogen dissociation degree and H- production in resonant antenna-generated plasmas

Abstract : A new generation of Neutral Beam systems will be required in future fusion reactors, such as DEMO, able to deliver high power (up to 150 MW) with high neutral energy (>1 MeV). Negative ion beams can attain this performance, resulting in a strong research focus on negative ion production from either surface or volumetric plasma sources. A novel helicon plasma source, employing on a resonant birdcage network antenna, is currently under study at the Swiss Plasma Center (SPC), before installation on the Cybele negative ion source [1] at CEA-IRFM. The source delivers up to 10 kW at 13.56 MHz, and was installed on a linear (1.8 m length) Resonant Antenna Ion Device (RAID). Passive spectroscopic measurements of the Ha, Hb and Hg Balmer lines and of all the diagonal Fulcher-a bands were performed with a sensitive f/2 spectrometer. Multiple viewing lines setup and an absolute intensity calibration were used to determine the plasma radiance profile, with a space resolution < 3 mm. A minimum Fisher regularisation algorithm is then applied to calculate the absolute emissivity profile for each emission line, in cylindrical symmetry as experimentally observed. An error estimate of the Abel-inverted profiles was performed using a Monte Carlo approach. Finally, an RF-compensated Langmuir probe measured the electron temperature and density profiles. The measured absolute line emissivities, electron density and temperature are interpreted using the collisional-radiative code YACORA [2] which estimates the dissociation degree and the distribution of the different atomic and molecular species, including the density of negative ions. In this paper, the results of a power scan up to 5 kW in conditions satisfying DEMO requirements, i.e. p 0:3 Pa and B 150 G, are shown.
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Poster communications
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Contributor : Emmanuelle Vernay <>
Submitted on : Tuesday, August 30, 2016 - 2:46:08 PM
Last modification on : Thursday, November 19, 2020 - 1:01:42 PM


  • HAL Id : in2p3-01357794, version 1



C. Marini, P. Demolon, B. P. Duval, I. Furno, A. A. Howling, et al.. Spectroscopic measurements of hydrogen dissociation degree and H- production in resonant antenna-generated plasmas. 43rd Conference on Plasma Physics, Jul 2016, Leuven, Belgium. ⟨in2p3-01357794⟩



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