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Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

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Abstract
Two ion cyclotron range of frequencies ( ICRF) heating schemes proposed for the half-field operation phase of ITER in hydrogen plasmas-fundamental H majority and second harmonic He-3 ICRF heating-were recently investigated in JET. Although the same magnetic field and RF frequencies (f approximate to 42 MHz and f approximate to 52 MHz, respectively) were used, the density and particularly the plasma temperature were lower than those expected in the initial phase of ITER. Unlike for the well-performing H minority heating scheme to be used in He-4 plasmas, modest heating efficiencies (n = P-absorbed/P-launched < 40%) with dominant electron heating were found in both H plasma scenarios studied, and enhanced plasma-wall interaction manifested by high radiation losses and relatively large impurity content in the plasma was observed. This effect was stronger in the He-3 ICRF heating case than in the H majority heating experiments and it was verified that concentrations as high as similar to 20% are necessary to observe significant ion heating in this case. The RF acceleration of the heated ions was modest in both cases, although a small fraction of the 3He ions reached about 260 keV in the second harmonic He-3 heating experiments when 5MW of ICRF power was applied. Considerable RF acceleration of deuterium beam ions was also observed in some discharges of the He-3 heating experiments (where both the second and third harmonic ion cyclotron resonance layers of the D ions are inside the plasma) whilst it was practically absent in the majority hydrogen heating scenario. While hints of improved RF heating efficiency as a function of the plasma temperature and plasma dilution (with He-4) were confirmed in the H majority case, the He-3 concentration was the main handle on the heating efficiency in the second harmonic He-3 heating scenario.
Keywords
SPECTROSCOPY, DT PLASMAS, TOKAMAK, SYSTEM

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Chicago
Lerche, E, D Van Eester, TJ Johnson, T Hellsten, J Ongena, ML Mayoral, D Frigione, et al. 2012. “Experimental Investigation of Ion Cyclotron Range of Frequencies Heating Scenarios for ITER’s Half-field Hydrogen Phase Performed in JET.” Plasma Physics and Controlled Fusion 54: 074008–074008.
APA
Lerche, E., Van Eester, D., Johnson, T., Hellsten, T., Ongena, J., Mayoral, M., Frigione, D., et al. (2012). Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER’s half-field hydrogen phase performed in JET. PLASMA PHYSICS AND CONTROLLED FUSION, 54, 074008–074008.
Vancouver
1.
Lerche E, Van Eester D, Johnson T, Hellsten T, Ongena J, Mayoral M, et al. Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER’s half-field hydrogen phase performed in JET. PLASMA PHYSICS AND CONTROLLED FUSION. 2012;54:074008–074008.
MLA
Lerche, E, D Van Eester, TJ Johnson, et al. “Experimental Investigation of Ion Cyclotron Range of Frequencies Heating Scenarios for ITER’s Half-field Hydrogen Phase Performed in JET.” PLASMA PHYSICS AND CONTROLLED FUSION 54 (2012): 074008–074008. Print.
@article{3005941,
  abstract     = {Two ion cyclotron range of frequencies ( ICRF) heating schemes proposed for the half-field operation phase of ITER in hydrogen plasmas-fundamental H majority and second harmonic He-3 ICRF heating-were recently investigated in JET. Although the same magnetic field and RF frequencies (f approximate to 42 MHz and f approximate to 52 MHz, respectively) were used, the density and particularly the plasma temperature were lower than those expected in the initial phase of ITER. Unlike for the well-performing H minority heating scheme to be used in He-4 plasmas, modest heating efficiencies (n = P-absorbed/P-launched {\textlangle} 40\%) with dominant electron heating were found in both H plasma scenarios studied, and enhanced plasma-wall interaction manifested by high radiation losses and relatively large impurity content in the plasma was observed. This effect was stronger in the He-3 ICRF heating case than in the H majority heating experiments and it was verified that concentrations as high as similar to 20\% are necessary to observe significant ion heating in this case. The RF acceleration of the heated ions was modest in both cases, although a small fraction of the 3He ions reached about 260 keV in the second harmonic He-3 heating experiments when 5MW of ICRF power was applied. Considerable RF acceleration of deuterium beam ions was also observed in some discharges of the He-3 heating experiments (where both the second and third harmonic ion cyclotron resonance layers of the D ions are inside the plasma) whilst it was practically absent in the majority hydrogen heating scenario. While hints of improved RF heating efficiency as a function of the plasma temperature and plasma dilution (with He-4) were confirmed in the H majority case, the He-3 concentration was the main handle on the heating efficiency in the second harmonic He-3 heating scenario.},
  author       = {Lerche, E and Van Eester, D and Johnson, TJ 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 Giroud, C and Gorini, G and Hellesen, C and Jacquet, P and Kiptily, V and Knipe, S and Krasilnikov, A and Maslov, M and Monakhov, I and Noble, C and Nocente, M and Pangione, L and Proverbio, I and Sergienko, G and Stamp, M and Studholme, W and Tardocchi, M and Vdovin, V and Versloot, T and Voitsekhovitch, I and Whitehurst, A and Wooldridge, E and Zoita, V},
  issn         = {0741-3335},
  journal      = {PLASMA PHYSICS AND CONTROLLED FUSION},
  language     = {eng},
  pages        = {074008--074008},
  title        = {Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET},
  url          = {http://dx.doi.org/10.1088/0741-3335/54/7/074008},
  volume       = {54},
  year         = {2012},
}

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