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N=2 ICRH of H majority plasmas in JET-ILW

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Abstract
Heating single ion species plasmas with ICRF is a challenging task: Fundamental ion cyclotron heating (w = w(ci)) suffers from the adverse polarization of the RF electric fields near the majority cyclotron resonance while second harmonic heating (w =2w(ci)) typically requires pre-heating of the plasma ions to become efficient. Recently, w =2wci ICRF heating was tested in JET-ILW hydrogen plasmas in the absence of neutral beam injection (L-mode). Despite the lack of pre-heating, up to 6MW of ICRF power were coupled to the plasma leading to a transition to H-mode for P-ICRH>5MW in most discharges. Heating efficiencies between 0.65-0.85 were achieved as a combination of the low magnetic field adopted (enhanced finite Larmor radius effects) and the deliberate slow rise of the ICRF power, allowing time for a fast ion population to gradually build-up leading to a systematic increase of the wave absorptivity. Although fast ion tails are a common feature of harmonic ICRF heating, the N=2 majority heating features moderate tail energies (<500keV) except at very low plasma densities (n(e0)<3x10(19)/m(3)), where fast H tails in the MeV range developed and fast ion losses became significant, leading to enhanced plasma wall interaction. The main results of these experiments will be reported.

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MLA
Lerche, E et al. “N=2 ICRH of H Majority Plasmas in JET-ILW.” AIP Conference Proceedings. Vol. 1689. AIP Publishing, 2015. Print.
APA
Lerche, E., Van Eester, D., Kazakov, Y., Jacquet, P., Monakhov, I., Goniche, M., Colas, L., et al. (2015). N=2 ICRH of H majority plasmas in JET-ILW. AIP Conference Proceedings (Vol. 1689). Presented at the 21st Topical Conference on Radiofrequency Power in Plasmas, AIP Publishing.
Chicago author-date
Lerche, E, D Van Eester, Y Kazakov, P Jacquet, I Monakhov, M Goniche, L Colas, et al. 2015. “N=2 ICRH of H Majority Plasmas in JET-ILW.” In AIP Conference Proceedings. Vol. 1689. AIP Publishing.
Chicago author-date (all authors)
Lerche, E, D Van Eester, Y Kazakov, P Jacquet, I Monakhov, M Goniche, L Colas, F Rimini, Kristel Crombé, R Dumont, V Kiptily, and M Santala. 2015. “N=2 ICRH of H Majority Plasmas in JET-ILW.” In AIP Conference Proceedings. Vol. 1689. AIP Publishing.
Vancouver
1.
Lerche E, Van Eester D, Kazakov Y, Jacquet P, Monakhov I, Goniche M, et al. N=2 ICRH of H majority plasmas in JET-ILW. AIP Conference Proceedings. AIP Publishing; 2015.
IEEE
[1]
E. Lerche et al., “N=2 ICRH of H majority plasmas in JET-ILW,” in AIP Conference Proceedings, CA, 2015, vol. 1689.
@inproceedings{7234692,
  abstract     = {Heating single ion species plasmas with ICRF is a challenging task: Fundamental ion cyclotron heating (w = w(ci)) suffers from the adverse polarization of the RF electric fields near the majority cyclotron resonance while second harmonic heating (w =2w(ci)) typically requires pre-heating of the plasma ions to become efficient. Recently, w =2wci ICRF heating was tested in JET-ILW hydrogen plasmas in the absence of neutral beam injection (L-mode). Despite the lack of pre-heating, up to 6MW of ICRF power were coupled to the plasma leading to a transition to H-mode for P-ICRH>5MW in most discharges. Heating efficiencies between 0.65-0.85 were achieved as a combination of the low magnetic field adopted (enhanced finite Larmor radius effects) and the deliberate slow rise of the ICRF power, allowing time for a fast ion population to gradually build-up leading to a systematic increase of the wave absorptivity. Although fast ion tails are a common feature of harmonic ICRF heating, the N=2 majority heating features moderate tail energies (<500keV) except at very low plasma densities (n(e0)<3x10(19)/m(3)), where fast H tails in the MeV range developed and fast ion losses became significant, leading to enhanced plasma wall interaction. The main results of these experiments will be reported.},
  articleno    = {040003},
  author       = {Lerche, E and Van Eester, D and Kazakov, Y and Jacquet, P and Monakhov, I and Goniche, M and Colas, L and Rimini, F and Crombé, Kristel and Dumont, R and Kiptily, V and Santala, M},
  booktitle    = {AIP Conference Proceedings},
  isbn         = {978-0-7354-1336-8},
  issn         = {0094-243X},
  language     = {eng},
  location     = {CA},
  pages        = {4},
  publisher    = {AIP Publishing},
  title        = {N=2 ICRH of H majority plasmas in JET-ILW},
  url          = {http://dx.doi.org/10.1063/1.4936486},
  volume       = {1689},
  year         = {2015},
}

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