Contrasting H-mode behaviour with deuterium fuelling and nitrogen seeding in the all-carbon and metallic versions of JET

被引：38

作者：

Maddison, G. P. ^{[1
]}

Giroud, C. ^{[1
]}

Alper, B. ^{[1
]}

Arnoux, G. ^{[1
]}

Balboa, I. ^{[1
]}

Beurskens, M. N. A. ^{[1
]}

Boboc, A. ^{[1
]}

Brezinsek, S. ^{[2
]}

Brix, M. ^{[1
]}

Clever, M. ^{[2
]}

Coelho, R. ^{[3
]}

Coenen, J. W. ^{[2
]}

Coffey, I. ^{[4
]}

da Silva Aresta Belo, P. C. ^{[3
]}

Devaux, S. ^{[5
]}

Devynck, P. ^{[6
]}

Eich, T. ^{[5
]}

Felton, R. C. ^{[1
]}

Flanagan, J. ^{[1
]}

Frassinetti, L. ^{[7
]}

Garzotti, L. ^{[1
]}

Groth, M. ^{[8
]}

Jachmich, S. ^{[9
]}

Jarvinen, A. ^{[8
]}

Joffrin, E. ^{[6
]}

Kempenaars, M. A. H. ^{[1
]}

Kruezi, U. ^{[2
]}

Lawson, K. D. ^{[1
]}

Lehnen, M. ^{[2
]}

Leyland, M. J. ^{[10
]}

Liu, Y. ^{[11
]}

Lomas, P. J. ^{[1
]}

Lowry, C. G. ^{[12
]}

Marsen, S. ^{[5
]}

Matthews, G. F. ^{[1
]}

McCormick, G. K. ^{[5
]}

Meigs, A. G. ^{[1
]}

Morris, A. W. ^{[1
]}

Neu, R. ^{[5
]}

Nunes, I. M. ^{[3
]}

Oberkofler, M. ^{[5
]}

Rimini, F. G. ^{[1
]}

Saarelma, S. ^{[1
]}

Sieglin, B. ^{[5
]}

Sips, A. C. C. ^{[12
]}

Sirinelli, A. ^{[1
]}

Stamp, M. F. ^{[1
]}

van Rooij, G. J. ^{[13
]}

Ward, D. J. ^{[1
]}

Wischmeier, M. ^{[5
]}

机构：

[1] EURATOM CCFE Fus Assoc, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England

[2] Assoc EURATOM FZJ, Forschungszentrum Julich, IEK Plasmaphys, Julich, Germany

[3] EURATOM IST Assoc, IPFN, P-1096 Lisbon, Portugal

[4] Queens Univ Belfast, Astrophys Res Ctr, Belfast BT7 1NN, Antrim, North Ireland

[5] EURATOM, Max Planck Inst Plasmaphys, D-85748 Garching, Germany

[6] EURATOM, CEA, CEA Cadarache, F-13108 St Paul Les Durance, France

[7] Assoc EURATOM VR, KTH, Div Fus Plasma Phys, SE-10044 Stockholm, Sweden

[8] Aalto Univ, Assoc EURATOM Tekes, Espoo 02150, Finland

[9] EURATOM, ERM KMS, Brussels, Belgium

[10] Univ York, York Plasma Inst, York YO10 5DD, N Yorkshire, England

[11] Chinese Acad Sci, Inst Plasma Phys, Hefei 230031, Peoples R China

[12] JET EFDA CSU, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England

[13] EURATOM, FOM, NL-3430 BE Nieuwegein, Netherlands

来源：

NUCLEAR FUSION | 2014年 / 54卷 / 07期

基金：

英国工程与自然科学研究理事会;

关键词：

JET; ITER; beryllium; tungsten; carbon; EDGE-LOCALIZED MODES; ITER-LIKE WALL; HIGH-DENSITY; ASDEX UPGRADE; DIII-D; TRANSPORT BARRIER; HIGH-CONFINEMENT; MAGNETOHYDRODYNAMIC STABILITY; RADIATIVE MANTLE; ENHANCED CONFINEMENT;

D O I：

10.1088/0029-5515/54/7/073016

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 former all-carbon wall on JET has been replaced with beryllium in the main torus and tungsten in the divertor to mimic the surface materials envisaged for ITER. Comparisons are presented between type I H-mode characteristics in each design by examining respective scans over deuterium fuelling and impurity seeding, required to ameliorate exhaust loads both in JET at full capability and in ITER. Attention is focused upon a common high-triangularity, single-null divertor configuration at 2.5 MA, q(95) approximate to 3.5 yielding the most robust all-C performance. Contrasting results between the alternative linings are found firstly in unseeded plasmas, for which purity is improved and intrinsic radiation reduced in the ITER-like wall (ILW) but normalized energy confinement is approximate to 30% lower than in all-C counterparts, owing to a commensurately lower (electron) pedestal temperature. Divertor recycling is also radically altered, with slower, inboard-outboard asymmetric transients at ELMs and spontaneous oscillations in between them. Secondly, nitrogen seeding elicits opposite responses in the ILW to all-C experience, tending to raise plasma density, reduce ELM frequency, and above all to recover (electron) pedestal pressure, hence global confinement, almost back to previous levels. A hitherto unrecognized role of light impurities in pedestal stability and dynamics is consequently suggested. Thirdly, while heat loads on the divertor outboard target between ELMs are successfully reduced in proportion to the radiative cooling and ELM frequency effects of N in both wall environments, more surprisingly, average power ejected by ELMs also declines in the same proportion for the ILW. Detachment between transients is simultaneously promoted. Finally, inter-ELM W sources in the ILW divertor tend to fall with N input, although core accumulation possibly due to increased particle confinement still leads to significantly less steady conditions than in all-C plasmas. This limitation of ILW H-modes so far will be readdressed in future campaigns to continue progress towards a fully integrated scenario suitable for D-T experiments on JET and for 'baseline' operation on ITER. The diverse changes in behaviour between all-C and ILW contexts demonstrate essentially the strong impact which boundary conditions and intrinsic impurities can have on tokamak-plasma states.

引用

页数：28

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