Study of quiescent H-mode plasmas in ASDEX Upgrade

W. Suttrop; G. D. Conway; L. Fattorini; L. D. Horton; T. Kurki-Suonio; C. F. Maggi; M. Maraschek; H. Meister; R. Neu; Th Pütterich; M. Reich; A. C.C. Sips

doi:10.1088/0741-3335/46/5A/016

Study of quiescent H-mode plasmas in ASDEX Upgrade

W. Suttrop, G. D. Conway, L. Fattorini, L. D. Horton, T. Kurki-Suonio, C. F. Maggi, M. Maraschek, H. Meister, R. Neu, Th Pütterich, M. Reich, A. C.C. Sips

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Abstract

In a recent campaign with counter-current neutral beam injection (NBI), the quiescent high confinement mode (QH-mode) is studied in ASDEX Upgrade. The QH-mode regime is obtained with all accessible NBI angles, with and without additional ion cyclotron heating, at various values of edge safety factor q ₉₅ and at values of Z_eff down to 2.5 after fresh boronization. In contrast to the ELMy H-mode, the pedestal pressure depends significantly on radial heat flux in the QH-mode, giving rise to a reduced heating power degradation of H-mode confinement. The 'edge harmonic oscillation', a characteristic MHD feature of the QH-mode that replaces ELMs, occurs at rational surfaces in the H-mode barrier region, and has so far been found only with a toroidal mode number n = 1. These conditions seem to define windows in q₉₅ for favourable QH-mode access.

Original language	English
Pages (from-to)	A151-A156
Journal	Plasma Physics and Controlled Fusion
Volume	46
Issue number	5 SUPPL. A
DOIs	https://doi.org/10.1088/0741-3335/46/5A/016
State	Published - May 2004
Externally published	Yes

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title = "Study of quiescent H-mode plasmas in ASDEX Upgrade",

abstract = "In a recent campaign with counter-current neutral beam injection (NBI), the quiescent high confinement mode (QH-mode) is studied in ASDEX Upgrade. The QH-mode regime is obtained with all accessible NBI angles, with and without additional ion cyclotron heating, at various values of edge safety factor q 95 and at values of Zeff down to 2.5 after fresh boronization. In contrast to the ELMy H-mode, the pedestal pressure depends significantly on radial heat flux in the QH-mode, giving rise to a reduced heating power degradation of H-mode confinement. The 'edge harmonic oscillation', a characteristic MHD feature of the QH-mode that replaces ELMs, occurs at rational surfaces in the H-mode barrier region, and has so far been found only with a toroidal mode number n = 1. These conditions seem to define windows in q95 for favourable QH-mode access.",

author = "W. Suttrop and Conway, {G. D.} and L. Fattorini and Horton, {L. D.} and T. Kurki-Suonio and Maggi, {C. F.} and M. Maraschek and H. Meister and R. Neu and Th P{\"u}tterich and M. Reich and Sips, {A. C.C.}",

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AU - Suttrop, W.

AU - Conway, G. D.

AU - Fattorini, L.

AU - Horton, L. D.

AU - Kurki-Suonio, T.

AU - Maggi, C. F.

AU - Maraschek, M.

AU - Meister, H.

AU - Neu, R.

AU - Pütterich, Th

AU - Reich, M.

AU - Sips, A. C.C.

PY - 2004/5

Y1 - 2004/5

N2 - In a recent campaign with counter-current neutral beam injection (NBI), the quiescent high confinement mode (QH-mode) is studied in ASDEX Upgrade. The QH-mode regime is obtained with all accessible NBI angles, with and without additional ion cyclotron heating, at various values of edge safety factor q 95 and at values of Zeff down to 2.5 after fresh boronization. In contrast to the ELMy H-mode, the pedestal pressure depends significantly on radial heat flux in the QH-mode, giving rise to a reduced heating power degradation of H-mode confinement. The 'edge harmonic oscillation', a characteristic MHD feature of the QH-mode that replaces ELMs, occurs at rational surfaces in the H-mode barrier region, and has so far been found only with a toroidal mode number n = 1. These conditions seem to define windows in q95 for favourable QH-mode access.

AB - In a recent campaign with counter-current neutral beam injection (NBI), the quiescent high confinement mode (QH-mode) is studied in ASDEX Upgrade. The QH-mode regime is obtained with all accessible NBI angles, with and without additional ion cyclotron heating, at various values of edge safety factor q 95 and at values of Zeff down to 2.5 after fresh boronization. In contrast to the ELMy H-mode, the pedestal pressure depends significantly on radial heat flux in the QH-mode, giving rise to a reduced heating power degradation of H-mode confinement. The 'edge harmonic oscillation', a characteristic MHD feature of the QH-mode that replaces ELMs, occurs at rational surfaces in the H-mode barrier region, and has so far been found only with a toroidal mode number n = 1. These conditions seem to define windows in q95 for favourable QH-mode access.

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SP - A151-A156

JO - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

IS - 5 SUPPL. A

ER -

Study of quiescent H-mode plasmas in ASDEX Upgrade

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