Journal ArticleDOI
Chapter 3: MHD stability, operational limits and disruptions
T. C. Hender,J.C. Wesley,J.M. Bialek,Anders Bondeson,Allen H. Boozer,R.J. Buttery,Am Garofalo,Timothy Goodman,Robert Granetz,Y. Gribov,O. Gruber,Mikhail Gryaznevich,G. Giruzzi,Sibylle Günter,Nobuhiko Hayashi,Per Helander,Chris Hegna,D. F. Howell,D.A. Humphreys,G. T. A. Huysmans,A.W. Hyatt,Akihiko Isayama,Stephen Jardin,Yasunori Kawano,A. Kellman,C.E. Kessel,H. R. Koslowski,R. J. La Haye,E. Lazzaro,Yueqiang Liu,V.E. Lukash,J. Manickam,S. Medvedev,V. Mertens,S. V. Mirnov,Y. Nakamura,G.A. Navratil,M. Okabayashi,Takahisa Ozeki,Roberto Paccagnella,G. Pautasso,F. Porcelli,V. D. Pustovitov,V. Riccardo,M. Sato,Olivier Sauter,M.J. Schaffer,Michiya Shimada,Piergiorgio Sonato,E. J. Strait,M. Sugihara,Manabu Takechi,A. D. Turnbull,E. Westerhof,D.G. Whyte,R. Yoshino,H. Zohm +56 more
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A review of recent advances in the area of MHD stability and disruptions, since the publication of the 1999 ITER Physics Basis document (1999 Nucl. Fusion 39 2137-2664), is reviewed in this paper.Abstract:
Progress in the area of MHD stability and disruptions, since the publication of the 1999 ITER Physics Basis document (1999 Nucl. Fusion 39 2137-2664), is reviewed. Recent theoretical and experimental research has made important advances in both understanding and control of MHD stability in tokamak plasmas. Sawteeth are anticipated in the ITER baseline ELMy H-mode scenario, but the tools exist to avoid or control them through localized current drive or fast ion generation. Active control of other MHD instabilities will most likely be also required in ITER. Extrapolation from existing experiments indicates that stabilization of neoclassical tearing modes by highly localized feedback-controlled current drive should be possible in ITER. Resistive wall modes are a key issue for advanced scenarios, but again, existing experiments indicate that these modes can be stabilized by a combination of plasma rotation and direct feedback control with non-axisymmetric coils. Reduction of error fields is a requirement for avoiding non-rotating magnetic island formation and for maintaining plasma rotation to help stabilize resistive wall modes. Recent experiments have shown the feasibility of reducing error fields to an acceptable level by means of non-axisymmetric coils, possibly controlled by feedback. The MHD stability limits associated with advanced scenarios are becoming well understood theoretically, and can be extended by tailoring of the pressure and current density profiles as well as by other techniques mentioned here. There have been significant advances also in the control of disruptions, most notably by injection of massive quantities of gas, leading to reduced halo current fractions and a larger fraction of the total thermal and magnetic energy dissipated by radiation. These advances in disruption control are supported by the development of means to predict impending disruption, most notably using neural networks. In addition to these advances in means to control or ameliorate the consequences of MHD instabilities, there has been significant progress in improving physics understanding and modelling. This progress has been in areas including the mechanisms governing NTM growth and seeding, in understanding the damping controlling RWM stability and in modelling RWM feedback schemes. For disruptions there has been continued progress on the instability mechanisms that underlie various classes of disruption, on the detailed modelling of halo currents and forces and in refining predictions of quench rates and disruption power loads. Overall the studies reviewed in this chapter demonstrate that MHD instabilities can be controlled, avoided or ameliorated to the extent that they should not compromise ITER operation, though they will necessarily impose a range of constraints.read more
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Journal ArticleDOI
Comparison of Advanced Machine Learning Tools for Disruption Prediction and Disruption Studies
TL;DR: Methods to optimize the training data set and the potential of kernels-based advanced machine learning tools are explored and assessed and it is shown that the RVM algorithm performs well when it is trained on a small set of discharges compared to the traditional methods.
Experimental Study of a 100-kW class Applied-Field MPD Thruster
R Albertoni,P. Rossetti,Fabrizio Paganucci,Mariano Andrenucci,Matteo Zuin,E. Martinez,Roberto Cavazzana +6 more
TL;DR: In this paper, a new 100 kW, gas-fed, applied field magneto-plasma-dynamic thruster has been designed, manufactured and preliminarily tested at Alta.
Journal ArticleDOI
Study of Plasma Current Decay in the Initial Phase of High Poloidal Beta Disruptions in JT-60U
Yoshihide Shibata,Kiyomasa Watanabe,Noriyasu Ohno,M. Okamoto,Akihiko Isayama,Kenichi Kurihara,Naoyuki Oyama,Tomohide Nakano,Yasunori Kawano,Go Matsunaga,Yutaka Kamada,Masayoshi Sugihara +11 more
TL;DR: Shibata et al. as mentioned in this paper used the experimental plasma resistance and inductance in high poloidal beta, βp, disruptions in JT-60U to validate some current decay models during the current quench.
Journal ArticleDOI
Development of a diagnostic technique based on Cherenkov effect for measurements of fast electrons in fusion devices.
V. V. Plyusnin,L. Jakubowski,J. Zebrowski,P. Duarte,Karol Malinowski,Horacio Fernandes,Carlos A. Silva,M. Rabinski,Marek J. Sadowski +8 more
TL;DR: A reasonable agreement was found between experimental data and the results of numerical modeling of the runaway electron generation in ISTTOK as well as between the data of both diagnostics.
Journal ArticleDOI
Extension of Shafranov’s Equilibrium Theory to the Description of Current Quenches Affected by Resistive Wall Dissipation in Tokamaks
TL;DR: In this paper, an equation for the column position in a tokamak is derived with account of the resistive wall reaction on the changes in the plasma, which is treated as time-dependent.
References
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Journal ArticleDOI
Chapter 1: Overview and summary
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TL;DR: In this paper, the authors describe the processes that will determine the properties of the plasma edge and its interaction with material elements in ITER and compare their predictions with the new experimental results.
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Chapter 2: Plasma confinement and transport
E. J. Doyle,Wayne A Houlberg,Yutaka Kamada,V. S. Mukhovatov,T.H. Osborne,A. R. Polevoi,G. Bateman,J. W. Connor,J. G. Cordey,T. Fujita,Xavier Garbet,T. S. Hahm,L. D. Horton,A. E. Hubbard,F. Imbeaux,Frank Jenko,J. E. Kinsey,Yasuaki Kishimoto,J.X. Li,T. C. Luce,Y. R. Martin,M. Ossipenko,V.V. Parail,A. G. Peeters,T. L. Rhodes,J. E. Rice,C. M. Roach,V. A. Rozhansky,F. Ryter,G. Saibene,R. Sartori,A. C. C. Sips,J. A. Snipes,M. Sugihara,E. J. Synakowski,H. Takenaga,Tomonori Takizuka,K. Thomsen,M. R. Wade,H. R. Wilson,Itpa Confinement Database,Itpa Pedestal +41 more
TL;DR: The understanding and predictive capability of transport physics and plasma confinement is reviewed from the perspective of achieving reactor-scale burning plasmas in the ITER tokamak, for both core and edge plasma regions.
Journal ArticleDOI
Equilibrium analysis of current profiles in tokamaks
TL;DR: In this paper, an efficient method is given for self-consistent reconstruction of the tokamak current profiles and their associated magnetic topology using the magnetohydrodynamic (MHD) equilibrium constraint from external magnetic measurements, kinetic profile measurements, internal poloidal magnetic field measurements, and topological information from soft X-ray (SXR) measurements.
Journal ArticleDOI
Helical temperature perturbations associated with tearing modes in tokamak plasmas
TL;DR: In this article, an investigation into the electron temperature perturbations associated with tearing modes in tokamak plasmas was made, and it was found that there is a critical magnetic island width below which the conventional picture where the temperature is flattened inside the separatrix is invalid.
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