The role of the current profile in the improved H-mode scenario in ASDEX Upgrade

Stober, J.; Sips, A. C. C.; Angioni, C.; Forest, C. B.; Gruber, O.; Hobirk, J.; Horton, L. D.; Maggi, C. F.; Maraschek, M.; Martin, P.; Carthy, P. J. Mc; Mertens, V.; Na, Y.-S.; Reich, M.; Stäbler, A.; Tardini, G.; Zohm, H.

doi:10.1088/0029-5515/47/8/002

Cited by 39 publications

(76 citation statements)

References 19 publications

(47 reference statements)

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“…1 and Table I. Recently improved H-modes have also been obtained in discharges q 95 > 4 without preheating [12]. Also these discharges (marked as red symbols) are included in Fig.…”

Section: Improved H-modes At Asdex Upgradementioning

confidence: 80%

“…Also (4,3) NTM activity is observed and no sawteeth are present throughout discharge. It is reported in [12] that in improved Hmodes without (3,2) NTM activity, H 98 (y,2) is typically higher. With the increase of beta during the pulse, H 98 (y,2) continues to rise until it reaches 1.4 at β N =2.9.…”

Section: Operation At Q 95 = 3-5mentioning

confidence: 94%

“…More detailed investigations at ASDEX Upgrade, on the role of the q-profile in improved H-modes [12], on the documentation of the edge pedestal in these discharges [14] and on the role of pedestal in improved confinement discharges for various experiments [13] are ongoing to establish a physics basis for extrapolation of these results to ITER. Most of this research is coordinated by the International Tokamak Physics Activity (ITPA).…”

Section: Improved H-modes At Asdex Upgradementioning

confidence: 99%

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The performance of improved H-modes at ASDEX Upgrade and projection to ITER

et al. 2007

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Since 1998 ASDEX Upgrade has developed stationary H-modes that routinely obtain confinement enhancement factors H98(y,2) > 1 and normalized beta, βN = 2–3. These discharges are characterized by a q-profile with low magnetic shear in the centre and q(0) ∼ 1. New results presented here concentrate on extending the operational range of these improved H-modes at ASDEX Upgrade and extrapolating the results to ITER. Discharges are obtained at high density, over a wide range of plasma collisionality and with a first wall predominantly covered by tungsten coated carbon tiles. The performance is optimized for q95 ranging from 3 to 5. At q95 ∼ 3 real time control of βN is used and in some cases ECCD to suppress NTM activity at low βN ∼ 2. For the extrapolation to ITER, the fusion power is calculated using the same thermal beta (βN,th) and kinetic profile shapes as obtained in ASDEX Upgrade and setting ⟨ne⟩/nGW = 0.85. The fusion gain that could be obtained is evaluated using different confinement scaling expressions. The results indicate that improved H-modes are a candidate for an ITER hybrid scenario or could extend ITER operation beyond what is currently foreseen using standard H-modes.

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“…1 and Table I. Recently improved H-modes have also been obtained in discharges q 95 > 4 without preheating [12]. Also these discharges (marked as red symbols) are included in Fig.…”

Section: Improved H-modes At Asdex Upgradementioning

confidence: 80%

Section: Operation At Q 95 = 3-5mentioning

confidence: 94%

Section: Improved H-modes At Asdex Upgradementioning

confidence: 99%

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The performance of improved H-modes at ASDEX Upgrade and projection to ITER

et al. 2007

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“…For example, sawtooth free hybrid discharges can be obtained in ASDEX Upgrade either with fishbone or (3,2) NTM activity, the latter having a smaller improvement in confinement w.r.t. standard sawtoothing H-mode [25].…”

Section: Fig 4: Electron Fishbones In Ftumentioning

confidence: 99%

21st IAEA Fusion Energy Conference: summary of sessions EX/D, EX/S and EX/W

Zohm

2007

Nucl. Fusion

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“…The experiment started from the assumption that the central part of the q-profile plays an important role in the explanation of the observed confinement differences between the different tokamaks. In ASDEX Upgrade this has been shown for some cases of different confinement in similar discharges [10].…”

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confidence: 93%

Improved confinement in JET hybrid discharges

Hobirk

Imbeaux

Crisanti

et al. 2012

Plasma Phys. Control. Fusion

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Abstract.A new technique has been developed to produce plasmas with improved confinement relative to the H 98,y2 scaling law [1] on the JET Tokamak. In the mid size Tokamaks ASDEX Upgrade and DIII-D heating during the current formation is used to produce a flat q-profile with a minimum close to 1. On JET this technique leads to q-profiles with similar minimum q but opposite to the other Tokamaks not to an improved confinement state. By changing the method utilising a faster current ramp with temporary higher current than in the flattop (current over shoot) plasmas with improved confinement (H 98,y2 = 1.35) and good stability (β N ≈ 3) have been produced and extended to many confinement times only limited by technical constraints. The increase in H 98,y2 -factor is stronger with more heating

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The role of the current profile in the improved H-mode scenario in ASDEX Upgrade

Cited by 39 publications

References 19 publications

The performance of improved H-modes at ASDEX Upgrade and projection to ITER

The performance of improved H-modes at ASDEX Upgrade and projection to ITER

21st IAEA Fusion Energy Conference: summary of sessions EX/D, EX/S and EX/W

Improved confinement in JET hybrid discharges

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