Nuclear Fusion (Jan 2024)

First high-power helicon results from DIII-D

  • R.I. Pinsker,
  • B. Van Compernolle,
  • S.X. Tang,
  • J.B. Lestz,
  • C.P. Moeller,
  • C.C. Petty,
  • A. Dupuy,
  • J.P. Squire,
  • A.M. Garofalo,
  • M. Porkolab,
  • J.C. Rost,
  • S.G. Baek,
  • A. Nagy,
  • S. Chowdhury,
  • N.A. Crocker,
  • G.H. Degrandchamp,
  • A.G. McLean,
  • K.R. Gage,
  • A. Marinoni,
  • E.H. Martin,
  • G. Ronchi,
  • the DIII-D Team

DOI
https://doi.org/10.1088/1741-4326/ad78e8
Journal volume & issue
Vol. 64, no. 12
p. 126058

Abstract

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More than 0.6 MW of rf power at 476 MHz has been coupled to DIII-D plasmas by launching helicon (whistler) waves with a traveling-wave antenna (comb-line) in the fast-wave polarization (Van Compernolle et al 2021 Nucl. Fusion 61 116034) which resulted in the observation of electron heating of the core plasma with single-pass absorption based on ray-tracing in L-mode discharges. The coupling performance of the 1.5 m wide 30-element comb-line traveling-wave antenna has been consistent with expectations based on the 2015–2016 experiments on DIII-D with a low-power 12-element prototype (Pinsker et al 2018 Nucl. Fusion 58 106007). The conditioning process that was necessary to carry out high-power experiments is discussed; rf-specific impurities have not been observed. Parametric decay instabilities have been observed and are being investigated as a potential edge absorption mechanism (Porkolab et al 2023 AIP Conf. Proc. 2984 070004).

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