Journal ArticleDOI
ELM-induced transient tungsten melting in the JET divertor
J. W. Coenen,G. Arnoux,B. Bazylev,G. F. Matthews,A. Autricque,I. Balboa,M. Clever,R. Dejarnac,I. H. Coffey,Yann Corre,Stéphane Devaux,Lorenzo Frassinetti,Estelle Gauthier,J. Horacek,S. Jachmich,Matthias Komm,M. Knaup,K. Krieger,S. Marsen,A. Meigs,Ph. Mertens,R.A. Pitts,T. Puetterich,M. Rack,M.F. Stamp,Gennady Sergienko,Patrick Tamain,V. Thompson,Jet-Efda Contributors +28 more
Reads0
Chats0
TLDR
In this paper, the outer strike point of a full-tungsten (W) divertor was moved towards the leading edge of the W divertor and the base temperature was raised within 1 s to a level allowing transient melting during the subsequent 0.5 s.Abstract:
The original goals of the JET ITER-like wall included the study of the impact of an all W divertor on plasma operation (Coenen et al 2013 Nucl. Fusion 53 073043) and fuel retention (Brezinsek et al 2013 Nucl. Fusion 53 083023). ITER has recently decided to install a full-tungsten (W) divertor from the start of operations. One of the key inputs required in support of this decision was the study of the possibility of W melting and melt splashing during transients. Damage of this type can lead to modifications of surface topology which could lead to higher disruption frequency or compromise subsequent plasma operation. Although every effort will be made to avoid leading edges, ITER plasma stored energies are sufficient that transients can drive shallow melting on the top surfaces of components. JET is able to produce ELMs large enough to allow access to transient melting in a regime of relevance to ITER. Transient W melt experiments were performed in JET using a dedicated divertor module and a sequence of I-P = 3.0 MA/B-T = 2.9 T H-mode pulses with an input power of P-IN = 23 MW, a stored energy of similar to 6 MJ and regular type I ELMs at Delta W-ELM = 0.3 MJ and f(ELM) similar to 30 Hz. By moving the outer strike point onto a dedicated leading edge in the W divertor the base temperature was raised within similar to 1 s to a level allowing transient, ELM-driven melting during the subsequent 0.5 s. Such ELMs (delta W similar to 300 kJ per ELM) are comparable to mitigated ELMs expected in ITER (Pitts et al 2011 J. Nucl. Mater. 415 (Suppl.) S957-64). Although significant material losses in terms of ejections into the plasma were not observed, there is indirect evidence that some small droplets (similar to 80 mu m) were released. Almost 1 mm (similar to 6 mm(3)) of W was moved by similar to 150 ELMs within 7 subsequent discharges. The impact on the main plasma parameters was minor and no disruptions occurred. The W-melt gradually moved along the leading edge towards the high-field side, driven by j x B forces. The evaporation rate determined from spectroscopy is 100 times less than expected from steady state melting and is thus consistent only with transient melting during the individual ELMs. Analysis of IR data and spectroscopy together with modelling using the MEMOS code Bazylev et al 2009 J. Nucl. Mater. 390-391 810-13 point to transient melting as the main process. 3D MEMOS simulations on the consequences of multiple ELMs on damage of tungsten castellated armour have been performed. These experiments provide the first experimental evidence for the absence of significant melt splashing at transient events resembling mitigated ELMs on ITER and establish a key experimental benchmark for the MEMOS code.read more
Citations
More filters
Journal ArticleDOI
Characterization of the in situ leading-edge-induced melting on the ITER-like tungsten divertor in EAST
Dahuan Zhu,Changjun Li,Changjun Li,Rui Ding,Baoguo Wang,Baoguo Wang,Junling Chen,Binfu Gao,Binfu Gao,Yongqi Gu,Xianzu Gong,East Team +11 more
Journal ArticleDOI
Effects of resonant magnetic perturbations on turbulence and transport in DIII-D L-mode plasmas
Saskia Mordijck,T. L. Rhodes,Lei Zeng,E. J. Doyle,L. W. Schmitz,Colin Chrystal,T J Strait,R.A. Moyer +7 more
TL;DR: In this paper, resonant magnetic perturbations (RMPs) affect the L- to H-mode power threshold and the particle pinch reverses from traditionally inward to outward, as a result, the density at the plasma edge increases, while the density in the core is reduced.
Journal ArticleDOI
Investigation of transient melting of tungsten by ELMs in ASDEX Upgrade
K. Krieger,B. Sieglin,M. Balden,J. W. Coenen,B. Göths,Florian Laggner,P. de Marne,G. F. Matthews,D. Nille,V. Rohde,R. Dejarnac,M. Faitsch,L. Giannone,A. Herrmann,J. Horacek,Matthias Komm,R.A. Pitts,Svetlana V. Ratynskaia,E. Thoren,Panagiotis Tolias,ASDEX-Upgrade Team,EUROfusion Mst Team +21 more
TL;DR: In this article, the effect of tungsten melting by power transients originating from edge localized modes (ELMs) was studied in the ASDEX Upgrade Tungsten samples were exposed to H-mode dis
Journal ArticleDOI
Fast measurements of the electron temperature and parallel heat flux in ELMy H-mode on the COMPASS tokamak
J. Adamek,Jakub Seidl,Matthias Komm,Vladimir Weinzettl,Radomir Panek,J. Stöckel,Martin Hron,P. Hacek,Martin Imrisek,Petr Vondracek,J. Horacek,A. Devitre +11 more
TL;DR: In this paper, the electron temperature and parallel heat flux were measured in the COMPASS tokamak scrape-off layer (SOL) and divertor region during ELMy H-mode plasmas.
Journal ArticleDOI
Simulations of thermionic suppression during tungsten transient melting experiments
Matthias Komm,Panagiotis Tolias,Svetlana V. Ratynskaia,R. Dejarnac,J. P. Gunn,K. Krieger,A. Podolnik,R.A. Pitts,Radomir Panek +8 more
TL;DR: In this paper, the authors show that the unimpeded component of a Tungsten (W) melting magnet can even lead to tungsten melting under steady state and especially during transient conditions.
References
More filters
Journal ArticleDOI
Steady-state radiative cooling rates for low-density, high-temperature plasmas
TL;DR: For 47 elements in the range 2 ≤ Z ≤ 92, steady-state radiative cooling rates, average charge states, and mean square charge states have been calculated for low-density, high-temperature plasmas (n e ≲ 10 16 electrons/cm 3 and T = 0.002-100 keV) as discussed by the authors.
Journal ArticleDOI
A full tungsten divertor for ITER: Physics issues and design status
R.A. Pitts,S. Carpentier,Frederic Escourbiac,T. Hirai,V. Komarov,S.W. Lisgo,A.S. Kukushkin,A. Loarte,Mario Merola,A. Sashala Naik,R. Mitteau,Masayoshi Sugihara,B. Bazylev,P.C. Stangeby +13 more
TL;DR: In this article, the authors consider the risks engendered by the baseline divertor strategy with regard to known W plasma-material interaction issues and briefly present the current status of a possible full-tungsten (W) divertor design.
Journal ArticleDOI
Sustained Spheromak Physics Experiment (SSPX): design and physics results
E. B. Hooper,R. H. Bulmer,Bruce I. Cohen,D. N. Hill,C. T. Holcomb,B. Hudson,Harry McLean,L.D. Pearlstein,Carlos Romero-Talamas,Carl Sovinec,B. W. Stallard,R. D. Wood,Simon Woodruff +12 more
TL;DR: The Sustained Spheromak Physics Experiment (SSPX) as discussed by the authors was a high-temperature (Te up to 0.5 keV), coaxial helicity injection (CHI) formed by coaxial helical injection, with plasma duration of a few milliseconds following the high-current formation stage.
Journal ArticleDOI
Physics basis and design of the ITER plasma-facing components
R.A. Pitts,S. Carpentier,Frederic Escourbiac,T. Hirai,V. Komarov,A.S. Kukushkin,S.W. Lisgo,A. Loarte,Mario Merola,R. Mitteau,A.R. Raffray,Michiya Shimada,P.C. Stangeby +12 more
TL;DR: The ITER PFC design has now reached a rather mature stage following the 2007 ITER Design Review as discussed by the authors, and the key elements of the design, reviews the physics drivers, essentially thermal load specifications, which have defined the concept and discusses a selection of material and design issues.
Journal ArticleDOI
Fuel retention studies with the ITER-Like Wall in JET
S. Brezinsek,T. Loarer,V. Philipps,H. G. Esser,S. Grünhagen,R. Smith,R. C. Felton,J. W. Banks,P. Belo,A. Boboc,Jérôme Bucalossi,M. Clever,J. W. Coenen,I. H. Coffey,Stéphane Devaux,D. Douai,Michaele Freisinger,D. Frigione,M. Groth,A. Huber,J. Hobirk,S. Jachmich,S. Knipe,K. Krieger,U. Kruezi,S. Marsen,G. F. Matthews,A. Meigs,F. Nave,I. Nunes,Rudolf Neu,J. Roth,M.F. Stamp,S. Vartanian,U. Samm,Jet-Efda Contributors +35 more
TL;DR: In this article, the ITER-like wall (ILW) experiment at JET was used to demonstrate the plasma compatibility with metallic walls and the reduction in fuel retention, which confirmed the expected predictions concerning the plasma-facing material change in ITER and is in line with identification of fuel co-deposition with Be as the main mechanism for the residual long-term retention.
Related Papers (5)
Physics conclusions in support of ITER W divertor monoblock shaping
R.A. Pitts,S. Bardin,B. Bazylev,M.A. van den Berg,P. Bunting,S. Carpentier-Chouchana,J. W. Coenen,Yann Corre,R. Dejarnac,Frederic Escourbiac,Jonathan Gaspar,James Paul Gunn,T. Hirai,S-H. Hong,J. Horacek,D. Iglesias,Matthias Komm,K. Krieger,C.J. Lasnier,G. F. Matthews,Thomas Morgan,S. Panayotis,S. Pestchanyi,A. Podolnik,Richard E. Nygren,Dmitry Rudakov,G. De Temmerman,Petr Vondracek,J.G. Watkins +28 more