Journal ArticleDOI
Control and dissipation of runaway electron beams created during rapid shutdown experiments in DIII-D
E. M. Hollmann,Max E Austin,J.A. Boedo,N.H. Brooks,Nicolas Jc Commaux,N.W. Eidietis,David Humphreys,V.A. Izzo,A.N. James,T.C. Jernigan,A. Loarte,Jose Ramon Martin-Solis,R.A. Moyer,J.M. Muñoz-Burgos,P. B. Parks,Dmitry Rudakov,E. J. Strait,C.K. Tsui,M. A. Van Zeeland,J.C. Wesley,J.H. Yu +20 more
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TLDR
In this article, a broad distribution of the RE energy distribution with mean energy of order several MeV and peak energies of order 30?40?MeV was shown to be more skewed towards low energies than expected from avalanche theory, which may be linked to enhanced radial diffusion caused by the significant quantity of high-Z impurities (typically argon) in the plasma.Abstract:
DIII-D experiments on rapid shutdown runaway electron (RE) beams have improved the understanding of the processes involved in RE beam control and dissipation. Improvements in RE beam feedback control have enabled stable confinement of RE beams out to the volt-second limit of the ohmic coil, as well as enabling a ramp down to zero current. Spectroscopic studies of the RE beam have shown that neutrals tend to be excluded from the RE beam centre. Measurements of the RE energy distribution function indicate a broad distribution with mean energy of order several MeV and peak energies of order 30?40?MeV. The distribution function appears more skewed towards low energies than expected from avalanche theory. The RE pitch angle appears fairly directed (????0.2) at high energies and more isotropic at lower energies (??<?100?keV). Collisional dissipation of RE beam current has been studied by massive gas injection of different impurities into RE beams; the equilibrium assimilation of these injected impurities appears to be reasonably well described by radial pressure balance between neutrals and ions. RE current dissipation following massive impurity injection is shown to be more rapid than expected from avalanche theory?this anomalous dissipation may be linked to enhanced radial diffusion caused by the significant quantity of high-Z impurities (typically argon) in the plasma. The final loss of RE beams to the wall has been studied: it was found that conversion of magnetic to kinetic energy is small for RE loss times smaller than the background plasma ohmic decay time of order 1?2?ms.read more
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Journal ArticleDOI
Disruptions in ITER and strategies for their control and mitigation
Michael Lehnen,K. Aleynikova,P. Aleynikov,David Campbell,P. Drewelow,N.W. Eidietis,Yu. Gasparyan,Robert Granetz,Y. Gribov,N. Hartmann,E. M. Hollmann,V.A. Izzo,S. Jachmich,S.H. Kim,M. Kocan,H. R. Koslowski,D. V. Kovalenko,U. Kruezi,A. Loarte,S. Maruyama,G. F. Matthews,P. B. Parks,G. Pautasso,R.A. Pitts,C. Reux,V. Riccardo,R. Roccella,J. A. Snipes,A.J. Thornton,P. de Vries,Efda Jet Contributors +30 more
TL;DR: In this paper, a brief overview on the disruption loads and mitigation strategies for ITER and the physics basis which is continuously refined through the current disruption R&D programs is discussed.
Journal ArticleDOI
Status of research toward the ITER disruption mitigation system
E. M. Hollmann,P B Aleynikov,Tünde Fülöp,David Humphreys,V.A. Izzo,Michael Lehnen,V.E. Lukash,Gergely Papp,G. Pautasso,F. Saint-Laurent,Joseph Snipes +10 more
TL;DR: An overview of the present status of research toward the final design of the ITER disruption mitigation system (DMS) is given in this paper, where the authors discuss the physics and engineering constraints of the design of this system due to limitations on port access and the amount and species of injected impurities.
Journal ArticleDOI
Physics of runaway electrons in tokamaks
Journal ArticleDOI
An ITPA joint experiment to study runaway electron generation and suppression
Robert Granetz,B. Esposito,J. H. Kim,R. Koslowski,Michael Lehnen,Jose Ramon Martin-Solis,Carlos Paz-Soldan,Tongnyeol Rhee,J.C. Wesley,Long Zeng +9 more
TL;DR: In this paper, a joint experiment with the ITPA MHD group is conducted to measure the detection threshold conditions on a number of tokamaks under quasi-steady state conditions in which Vloop, ne, and REs can be well-diagnosed and compared to collisional theory.
Journal ArticleDOI
Numerical calculation of the runaway electron distribution function and associated synchrotron emission
TL;DR: It is found that the average synchrotron spectra emitted from realistic distribution functions are not well approximated by the emission of a single electron at the maximum energy.
References
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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
TL;DR: 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.
Journal ArticleDOI
A design retrospective of the DIII-D tokamak
TL;DR: The DIII-D tokamak as discussed by the authors has been the focus of a broad fusion plasma science research program since 1986, and it has been used extensively in the past 30 years.
Journal ArticleDOI
Theory for avalanche of runaway electrons in tokamaks
M.N. Rosenbluth,S.V. Putvinski +1 more
TL;DR: In this paper, an analysis of runaway electron formation and its evolution during disruptions in large tokamaks, where avalanche phenomena play a crucial role, is presented, but sufficiently accurate, analytical model suitable for one dimensional (1-D) transport codes is proposed.
Journal ArticleDOI
Bremsstrahlung spectra from electron interactions with screened atomic nuclei and orbital electrons
TL;DR: In this paper, a comprehensive set of bremsstrahlung cross sections (differential in the energy of the emitted photons) has been prepared, including results for electrons with energies from 1 keV to 10 GeV incident on neutral atoms with atomic numbers Z = 1 to 100.
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