Journal ArticleDOI
Frequency spectral broadening of lower hybrid waves in tokamak plasmas-causes and effects
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In this article, the frequency spectral broadening of lower hybrid (LH) waves injected into tokamak plasmas is extensively analyzed with reference mostly to experimental data from the ASDEX tokak.Abstract:
The frequency spectral broadening of lower hybrid (LH) waves injected into tokamak plasmas is extensively analysed with reference mostly to experimental data from the ASDEX tokamak. The link between the magnitude of the pump spectral width and the degradation of the LH current drive efficiency (up to a factor of 2), pointed out in previous works, is explained. The experimental behaviour of LH power absorption is also well reproduced, even in situations when the access of the launched LH waves to the core plasma should be largely forbidden. Experiments are described that are aimed at determining whether parametric decay instabilities (PDIs) or scattering of LH waves by density fluctuations in the plasma edge are causes of the broadening of the LH pump frequency spectrum. Fluctuations emerge as the largely dominant process, while no signature of PDI processes is observed. Careful measurements of the density fluctuations in the ASDEX scrape-off layer plasma allow the analytical description given by Andrews and Perkins (1983) to be assumed as the appropriate model for LH scattering. Indeed, it supplies the correct magnitude for the frequency spectral width of the LH pump, and explains quantitatively, together with a ray tracing code, why the CD efficiency decreases with the broadening of the pump spectrum. It can also account for the observed LH power absorption coefficientread more
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Overview of the FTU results
G. Pucella,E. Alessi,L. Amicucci,B. Angelini,M.L. Apicella,G. Apruzzese,G. Artaserse,E. Barbato,F. Belli,A. Bertocchi,William Bin,Luca Boncagni,A. Botrugno,Sergio Briguglio,Alessandro Bruschi,P. Buratti,G. Calabrò,A. Cardinali,C. Castaldo,F. Causa,Silvio Ceccuzzi,Cristina Centioli,R. Cesario,C. Cianfarani,V. Cocilovo,F. Crisanti,Ocleto D'Arcangelo,M. De Angeli,R. De Angelis,C. Di Troia,B. Esposito,Daniela Farina,Lorenzo Figini,G. Fogaccia,D. Frigione,V. Fusco,L. Gabellieri,Cristian Galperti,Saul Garavaglia,E. Giovannozzi,Gustavo Granucci,F. Iannone,M. Lontano,G. Maddaluno,C. Marchetto,M. Marinucci,D. Marocco,G. Mazzitelli,C. Mazzotta,A. Milovanov,D. Minelli,Francesco Mirizzi,A. Moro,S. Nowak,F. Orsitto,D. Pacella,L. Panaccione,M. Panella,V. Pericoli-Ridolfini,A. Pizzuto,Salvatore Podda,G. Ramogida,G. L. Ravera,A. Romano,Carlo Sozzi,A. A. Tuccillo,O. Tudisco,B. Viola,E. Vitale,Gregorio Vlad,V. Zanza,M. Zerbini,Fulvio Zonca,M. Aquilini,P. Cefali,E. Di Ferdinando,S. Di Giovenale,G. Giacomi,A. Grosso,V. Mellera,M. Mezzacappa,A. Pensa,P. Petrolini,V. Piergotti,B. Raspante,G. Rocchi,A. Sibio,B. Tilia,R. Tulli,M. Vellucci,D. Zannetti,S. Almaviva,G. P. Canal,Luisa Caneve,Daniele Carnevale,Mario Cavinato,S. Cirant,F. Colao,F. Crescenzi,B. P. Duval,R. Fantoni,L. Federspiel,Sergio Galeani,Giovanni Grosso,L. Jakubowski,A. N. Karpushov,D. Kim,E. Lazzaro,I.E. Lyublinski,Karol Malinowski,Jose Ramon Martin-Solis,Francesco Maviglia,M. Mosconi,Z. Popovic,M. Rabinski,M. Reale,H. Reimerdes,D. Ricci,Marco Riva,S. Roccella,J. X. Rossel,Marek J. Sadowski,Mario Sassano,Olivier Sauter,Duccio Testa,A.V. Vertkov,David N. Wagner,J. Zebrowski +127 more
TL;DR: In this paper, a real-time algorithm for disruption prediction, based on MHD activity signals from Mirnov coils, was developed exploiting a large database of disruptions, and a new actively cooled lithium limiter was inserted in the scrape-off layer, without any damage to the limiter surface.
Journal ArticleDOI
Electron-cyclotron wave scattering by edge density fluctuations in ITER
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Journal ArticleDOI
Measurements of ion cyclotron parametric decay of lower hybrid waves at the high-field side of Alcator C-Mod
Seung Gyou Baek,R.R. Parker,S. Shiraiwa,Gregory Wallace,P.T. Bonoli,Dan Brunner,Ian Faust,Amanda Hubbard,Brian LaBombard,Miklos Porkolab +9 more
TL;DR: In this paper, an ion cyclotron parametric decay instability (PDI) of lower hybrid (LH) waves is surveyed using edge Langmuir probes on the Alcator C-Mod tokamak.
Journal ArticleDOI
Experimental investigations of LHW–plasma coupling and current drive related to achieving H-mode plasmas in EAST
Bojiang Ding,E. H. Kong,Ming Li,Lei Zhang,Wei Wei,M. Wang,H. D. Xu,Yi Li,Bili Ling,Qing Zang,Gang Xu,Xiuwen Han,H. L. Zhao,Ling Zhang,Lin Zhao,Huaichuan Hu,Y. Yang,L. Liu,A. Ekedahl,M. Goniche,R. Cesario,Y. Peysson,J. Decker,V. Basiuk,P. Huynh,J.F. Artaud,Frederic Imbeaux,Jiafang Shan,Fukun Liu,Yuanzhe Zhao,Xianzu Gong,Liqun Hu,X. Gao,Haizhong Guo,B. N. Wan,Jiuyuan Li +35 more
TL;DR: In this paper, the effect of local gas puffing from electron and ion sides of a lower hybrid wave antenna on LHW?plasma coupling and high-density experiments with lower hybrid current drive (LHCD) are investigated in EAST.
Journal ArticleDOI
Lower hybrid current drive for the steady-state scenario
M. Goniche,L. Amicucci,Yu.F. Baranov,V. Basiuk,G. Calabrò,A. Cardinali,C. Castaldo,R. Cesario,J. Decker,D. Dodt,A. Ekedahl,Lorenzo Figini,J. Garcia,G. Giruzzi,Julien Hillairet,G. T. Hoang,A. E. Hubbard,E. Joffrin,K. K. Kirov,X. Litaudon,J. Mailloux,T. Oosako,R. Parker,V. Pericoli Ridolfini,Yves Peysson,P. Platania,F.G. Rimini,Pankaj Sharma,Carlo Sozzi,Gregory Wallace +29 more
TL;DR: Lower hybrid current drive (LHCD) experiments performed at a density close to that required for the steady-state (SS) scenario are reported in this paper, where a strong decay of the bremsstrahlung emission is observed when the density is increased, much faster that the prediction of LHCD modelling.
References
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Journal Article
Plasma Physics and Controlled Nuclear Fusion Research
TL;DR: In this paper, the first experiments in JET have been described, which show that this large tokamak behaves in a similar manner to smaller tokak, but with correspondingly improved plasma parameters.
Journal ArticleDOI
Theory of current-drive in plasmas
TL;DR: A variety of methods have been proposed to provide continuous current, including methods that utilize particle beams or radio-frequency waves in any of several frequency regimes as mentioned in this paper, and experimentation in these techniques has now involved major tokamak facilities worldwide.
Journal ArticleDOI
Heating in Toroidal Plasmas (Report on the 4th International Symposium, Rome, 21–28 March, 1984)
H. Knoepfel,G. Mazzitelli +1 more
TL;DR: The fourth International Symposium of the Varenna-Grenoble series, held in Rome from March 21 to 28, 1984, was organized by the Italian Commission for Nuclear and Alternative Energy Sources (ENEA) and the International School of Plasma Physics (Varenna) as mentioned in this paper.
Journal ArticleDOI
Numerical studies of current generation by radio‐frequency traveling waves
TL;DR: In this paper, a two-dimensional Fokker-planck equation with an added quasi-linear term was used to calculate the ratio of power dissipated to current generated.
Journal ArticleDOI
Toroidal and scattering effects on lower‐hybrid wave propagation
Paul Bonoli,Edward Ott +1 more
TL;DR: In this article, the effects of toricity and density fluctuations on the propagation of lower-hybrid waves are studied, and it is shown that for accessible waves the optimal poloidal launch point is near the top or bottom of the torus.
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