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Enhancing the mode conversion efficiency in JET plasmas with multiple mode conversion layers

(2011) AIP Conference Proceedings. 1406. p.301-308
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Abstract
The constructive interference effect described by Fuchs et al. [1] shows that the mode conversion and thereby the overall heating efficiency can be enhanced significantly when an integer number of fast wave wavelengths can be folded in between the high field side fast wave cutoff and the ion-ion hybrid layer(s) at which the ion Bernstein or ion cyclotron waves are excited. This effect was already experimentally identified in (3He)-D plasmas [2] and was recently tested in (3He)-H JET plasmas. The latter is an ‘inverted’ scenario, which differs significantly from the (3He)-D scenarios since the mode-conversion layer is positioned between the low field side edge of the plasma and the ion-cyclotron layer of the minority 3He ions (whereas the order in which a wave entering the plasma from the low field side encounters these layers is inverted in a ‘regular’ scenario), and because much lower 3He concentrations are needed to achieve the mode-conversion heating regime. The presence of small amounts of 4He and D in the discharges gave rise to an additional mode conversion layer on top of the expected one associated with 3He-H, which made the interpretation of the results more complex but also more interesting: Three different regimes could be distinguished as a function of X[3He], and the differing dynamics at the various concentrations could be traced back to the presence of these two mode conversion layers and their associated fast wave cutoffs. Whereas (1-D and 2-D) numerical modeling yields quantitative information on the RF absorptivity, recent analytical work by Kazakov [3] permits to grasp the dominant underlying wave interaction physics.
Keywords
constructive/destructive interference, ICRF heating, mode conversion, TOKAMAK, WAVE

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Chicago
Van Eester, D, E Lerche, T Johnson, T Hellsten, J Ongena, ML Mayoral, D Frigione, et al. 2011. “Enhancing the Mode Conversion Efficiency in JET Plasmas with Multiple Mode Conversion Layers.” In AIP Conference Proceedings, ed. Cynthia Philips and James Wilson, 1406:301–308. Melville, NY, USA: American Institute of Physics (AIP).
APA
Van Eester, D, Lerche, E., Johnson, T., Hellsten, T., Ongena, J., Mayoral, M., Frigione, D., et al. (2011). Enhancing the mode conversion efficiency in JET plasmas with multiple mode conversion layers. In Cynthia Philips & J. Wilson (Eds.), AIP Conference Proceedings (Vol. 1406, pp. 301–308). Presented at the 19th Topical conference on Radio Frequency Power in Plasmas, Melville, NY, USA: American Institute of Physics (AIP).
Vancouver
1.
Van Eester D, Lerche E, Johnson T, Hellsten T, Ongena J, Mayoral M, et al. Enhancing the mode conversion efficiency in JET plasmas with multiple mode conversion layers. In: Philips C, Wilson J, editors. AIP Conference Proceedings. Melville, NY, USA: American Institute of Physics (AIP); 2011. p. 301–8.
MLA
Van Eester, D, E Lerche, T Johnson, et al. “Enhancing the Mode Conversion Efficiency in JET Plasmas with Multiple Mode Conversion Layers.” AIP Conference Proceedings. Ed. Cynthia Philips & James Wilson. Vol. 1406. Melville, NY, USA: American Institute of Physics (AIP), 2011. 301–308. Print.
@inproceedings{2066427,
  abstract     = {The constructive interference effect described by Fuchs et al. [1] shows that the mode conversion and thereby the overall heating efficiency can be enhanced significantly when an integer number of fast wave wavelengths can be folded in between the high field side fast wave cutoff and the ion-ion hybrid layer(s) at which the ion Bernstein or ion cyclotron waves are excited. This effect was already experimentally identified in (3He)-D plasmas [2] and was recently tested in (3He)-H JET plasmas. The latter is an {\textquoteleft}inverted{\textquoteright} scenario, which differs significantly from the (3He)-D scenarios since the mode-conversion layer is positioned between the low field side edge of the plasma and the ion-cyclotron layer of the minority 3He ions (whereas the order in which a wave entering the plasma from the low field side encounters these layers is inverted in a {\textquoteleft}regular{\textquoteright} scenario), and because much lower 3He concentrations are needed to achieve the mode-conversion heating regime. The presence of small amounts of 4He and D in the discharges gave rise to an additional mode conversion layer on top of the expected one associated with 3He-H, which made the interpretation of the results more complex but also more interesting: Three different regimes could be distinguished as a function of X[3He], and the differing dynamics at the various concentrations could be traced back to the presence of these two mode conversion layers and their associated fast wave cutoffs. Whereas (1-D and 2-D) numerical modeling yields quantitative information on the RF absorptivity, recent analytical work by Kazakov [3] permits to grasp the dominant underlying wave interaction physics.},
  author       = {Van Eester, D and Lerche, E and Johnson, T and Hellsten, T and Ongena, J and Mayoral, ML and Frigione, D and Sozzi, C and Calabro, G and Lennholm, M and Beaumont, P and Blackman, T and Brennan, D and Brett, A and Cecconello, M and Coffey, I and Coyne, A and Cromb{\'e}, Kristel and Czarnecka, A and Felton, R and Gatu Johnson, M and Giroud, C and Gorini, G and Hellesen, C and Jacquet, P and Kazakov, Y and Kiptily, V and Knipe, S and Krasilnikov, A and Lin, Y and Maslov, M and Monakhov, I and Noble, C and Nocente, M and Pangioni, L and Proverbio, I and Stamp, M and Studholme, W and Tardocchi, M and Versloot, TW and Vdovin, V and Whitehurst, A and Wooldridge, E and Zoita, V},
  booktitle    = {AIP Conference Proceedings},
  editor       = {Philips, Cynthia and Wilson, James},
  isbn         = {9780735409781},
  issn         = {0094-243X},
  language     = {eng},
  location     = {Newport, RI, USA},
  pages        = {301--308},
  publisher    = {American Institute of Physics (AIP)},
  title        = {Enhancing the mode conversion efficiency in JET plasmas with multiple mode conversion layers},
  url          = {http://dx.doi.org/10.1063/1.3664981},
  volume       = {1406},
  year         = {2011},
}

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