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Journal Articles

Characteristics of the H-mode pedestal in improved confinement scenarios in ASDEX Upgrade, DIII-D, JET and JT-60U

Maggi, C. F.*; Groebner, R. J.*; Oyama, Naoyuki; Sartori, R.*; Horton, L. D.*; Sips, A. C. C.*; Suttrop, W.*; ASDEX Upgrade Team; Leonard, A.*; Luce, T. C.*; et al.

Nuclear Fusion, 47(7), p.535 - 551, 2007/07

 Times Cited Count:59 Percentile:89.69(Physics, Fluids & Plasmas)

Pedestal and global plasma parameters are compared in ELMy H-modes and improved confinement discharges from ASDEX Upgrade (AUG), DIII-D, JET and JT-60U with varying net input power. The pedestal top pressure increases moderately with power, in broad agreement with the power dependence of the H98(y,2) scaling. For all machines and all scenarios a robust correlation between the total and the pedestal thermal stored energy is observed. In AUG the improved confinement is due to improved pedestal confinement in improved H-modes with early heating and to both improved pedestal and core confinement in improved H-modes with late heating. In DIII-D the increase in confinement is due to improved confinement in the plasma core. JT-60U reversed shear H-modes have strong internal transport barriers and thus improved core performance. In all four tokamaks improved edge stability is correlated with increasing total $$beta_{p}$$ and H98(y,2) increases with pedestal $$beta_{p}$$.

Journal Articles

Edge pedestal physics and its implications for ITER

Kamada, Yutaka; Leonard, A. W.*; Bateman, G.*; Becoulet, M.*; Chang, C. S.*; Eich, T.*; Evans, T. E.*; Groebner, R. J.*; Guzdar, P. N.*; Horton, L. D.*; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03

no abstracts in English

Journal Articles

Characteristics of the H-mode pedestal in improved confinement scenarios in ASDEX Upgrade, DIII-D, JET and JT-60U

Maggi, C. F.*; Groebner, R. J.*; Oyama, Naoyuki; Sartori, R.*; Horton, L. D.*; Sips, A. C. C.*; Suttrop, W.*; ASDEX Upgrade Team; Leonard, T.*; Luce, T. C.*; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03

Pedestal and global plasma parameters are compared in ELMy H-mode discharges from ASDEX Upgrade (AUG), DIII-D, JET and JT-60U. The increase in pedestal pressure (p$$^{PED}$$) with power is continuous, reflecting the continuous transition from "standard H-mode" to "improved confinement scenario". In AUG improved H-modes p$$^{PED}$$ increases with power due to an increase of both pedestal top density and temperature. In DIII-D p$$^{PED}$$ increases primarily due to an increase of the pedestal temperature. In JT-60U high $$beta_{pol}$$ H-modes at $$q_{95}$$ = 6.5 and high $$delta$$ the improved confinement is due to an increase of $$W_{PED}$$, while in reversed shear H-modes to an increase of $$W_{core}$$. In JET hybrid discharges at 1.4 MA $$W_{th}$$ increases with power and $$delta$$ due to an increase of $$W_{PED}$$. In all four tokamaks improved edge stability is correlated to increasing total $$beta_{pol} $$ and H98(y,2) increases with pedestal $$beta_{pol}$$.

Journal Articles

Pedestal conditions for small ELM regimes in tokamaks

Oyama, Naoyuki; Gohil, P.*; Horton, L. D.*; Hubbard, A. E.*; Hughes, J. W.*; Kamada, Yutaka; Kamiya, Kensaku; Leonard, A. W.*; Loarte, A.*; Maingi, R.*; et al.

Plasma Physics and Controlled Fusion, 48(5A), p.A171 - A181, 2006/05

 Times Cited Count:65 Percentile:90.57(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Pedestal characteristics of H-mode plasmas in JT-60U and ASDEX Upgrade

Urano, Hajime; Kamada, Yutaka; Takizuka, Tomonori; Suttrop, W.*; Horton, L.*; Lang, P.*; Kubo, Hirotaka; Oyama, Naoyuki; Takenaga, Hidenobu; Asakura, Nobuyuki

Purazuma, Kaku Yugo Gakkai-Shi, 81(4), p.280 - 287, 2005/04

Role of the pedestal structure in ELMy H-mode plasmas for the core energy confinement and for the ELM energy losses have been investigated in JT-60U and ASDEX Upgrade. The confinement degradation seen at higher densities is attributed to the reduction of the pedestal temperature limited by the ELM activities and the stiffness of the temperature profiles. In high triangularity or impurity seeded H-modes, in which higher energy confinement is generally achieved, higher pedestal temperature is obtained by the improvement of the edge MHD stability or the density profile peaking, respectively. The upper bound of the ELM energy loss is characterised by the pedestal energy. The energy transport in between ELMs enhanced with increasing the pedestal collisionality reduces the ELM loss power fraction. It is also shown in ASDEX Upgrade that the continuous pellet injection is valid for the integrated performance of smaller ELM losses and favourable core confinement.

Journal Articles

Edge localized mode physics and operational aspects in tokamaks

B$'e$coulet, M.*; Huysmans, G.*; Sarazin, Y.*; Garbet, X.*; Ghendrih, P.*; Rimini, F.*; Joffrin, E.*; Litaudon, X.*; Monier-Garbet, P.*; An$'e$, J.-M.*; et al.

Plasma Physics and Controlled Fusion, 45(12A), p.A93 - A113, 2003/12

 Times Cited Count:83 Percentile:92.45(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Understanding of the H mode pedestal characteristics using the multimachine pedestal database

Hatae, Takaki; Sugihara, Masayoshi; Hubbard, A. E.*; Igitkhanov, Y.*; Kamada, Yutaka; Janeschitz, G.*; Horton, L. D.*; Oyabu, Nobuyoshi*; Osborne, T. H.*; Osipenko, M.*; et al.

Nuclear Fusion, 41(3), p.285 - 293, 2001/03

 Times Cited Count:39 Percentile:75.89(Physics, Fluids & Plasmas)

no abstracts in English

Oral presentation

Changes in the ELM characteristics by edge electron cyclotron wave injection

Oyama, Naoyuki; Yoon, S. W.*; Suttrop, W.*; Wolfrum, E.*; Isayama, Akihiko; Urano, Hajime; Kamada, Yutaka; JT-60 Team

no journal, , 

In JT-60U, the ELM heatload can be reduced by $${sim}30%$$ together with increasing the ELM frequency by injecting electron cyclotron wave (ECW) near the top of pedestal. In order to understand the required and optimum condition for the ELM control, edge ECW injection experiments have been performed in ASDEX Upgrade and KSTAR. As a result, clear increase in the ELM frequency was observed in all devices, but the level of ELM mitigation depends on the experimental condition.

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