Tungsten transport in JET H-mode plasmas in hybrid scenario, experimental observations and modelling

被引：160

作者：

Angioni, C. ^{[1
]}

Mantica, P. ^{[2
]}

Puetterich, T. ^{[1
]}

Valisa, M. ^{[3
]}

Baruzzo, M. ^{[3
]}

Belli, E. A. ^{[4
]}

Belo, P. ^{[5
]}

Casson, F. J. ^{[6
]}

Challis, C. ^{[6
]}

Drewelow, P. ^{[7
]}

Giroud, C. ^{[6
]}

Hawkes, N. ^{[6
]}

Hender, T. C. ^{[6
]}

Hobirk, J. ^{[1
]}

Koskela, T. ^{[8
]}

Taroni, L. Lauro ^{[3
]}

Maggi, C. F. ^{[1
]}

Mlynar, J. ^{[9
]}

Odstrcil, T.

Reinke, M. L. ^{[10
]}

Romanelli, M. ^{[6
]}

机构：

[1] Max Planck Inst Plasma Phys, D-85748 Garching, Germany

[2] CNR ENEA, Ist Fis Plasma, Milan, Italy

[3] Consorzio RFX CNR ENEA, I-35127 Padua, Italy

[4] Gen Atom, San Diego, CA 92186 USA

[5] IST, Inst Plasma & Fusao Nucl, Lisbon, Portugal

[6] CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England

[7] Max Planck Inst Plasma Phys, Greifswald, Germany

[8] Aalto Univ, Assoc EURATOM Tekes, FIN-00076 Aalto, Finland

[9] Acad Sci Czech Republ, Inst Plasma Phys, IPP CR, Prague, Czech Republic

[10] Univ York, Dept Phys, York YO10 5DD, N Yorkshire, England

来源：

NUCLEAR FUSION | 2014年 / 54卷 / 08期

基金：

英国工程与自然科学研究理事会;

关键词：

heavy impurity transport; H-mode hybrid scenario; neoclassical and turbulent transport; IMPURITY TRANSPORT; NEOCLASSICAL TRANSPORT; ACCUMULATION; TOKAMAKS; BARRIER; CONFINEMENT; ASYMMETRIES; PROFILE;

D O I：

10.1088/0029-5515/54/8/083028

中图分类号：

O35 [流体力学]; O53 [等离子体物理学];

学科分类号：

070204 ; 080103 ; 080704 ;

摘要：

The behaviour of tungsten in the core of hybrid scenario plasmas in JET with the ITER-like wall is analysed and modelled with a combination of neoclassical and gyrokinetic codes. In these discharges, good confinement conditions can be maintained only for the first 2-3 s of the high power phase. Later W accumulation is regularly observed, often accompanied by the onset of magneto-hydrodynamical activity, in particular neoclassical tearing modes (NTMs), both of which have detrimental effects on the global energy confinement. The dynamics of the accumulation process is examined, taking into consideration the concurrent evolution of the background plasma profiles, and the possible onset of NTMs. Two time slices of a representative discharge, before and during the accumulation process, are analysed with two independent methods, in order to reconstruct the W density distribution over the poloidal cross-section. The same time slices are modelled, computing both neoclassical and turbulent transport components and consistently including the impact of centrifugal effects, which can be significant in these plasmas, and strongly enhance W neoclassical transport. The modelling closely reproduces the observations and identifies inward neoclassical convection due to the density peaking of the bulk plasma in the central region as the main cause of the accumulation. The change in W neoclassical convection is directly produced by the transient behaviour of the main plasma density profile, which is hollow in the central region in the initial part of the high power phase of the discharge, but which develops a significant density peaking very close to the magnetic axis in the later phase. The analysis of a large set of discharges provides clear indications that this effect is generic in this scenario. The unfavourable impact of the onset of NTMs on the W behaviour, observed in several discharges, is suggested to be a consequence of a detrimental combination of the effects of neoclassical transport and of the appearance of an island.

引用

页数：26

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