Showing 991 - 1000 of 1463 Journals Results
2009
M. J. Hole L. C. Appel R. Martin
Over the past two decades, the increase in neutral-beam heating and particle production in magnetically confined fusion plasmas has led to an increase in energetic particle driven mode activity, much of which has an electromagnetic signature which can be detected by the use of external Mirnov coils. Typically, the frequency and spatial wave number …
Published2009
K. Tanaka K. Kawahata T. Tokuzawa T. Akiyama M. Yokoyama M. Shoji C. A. Michael L. N. Vyacheslavov S. Murakami A. Wakasa A. Mishchenko K. Muraoka S. Okajima H. Takenaga Lhd Experiment Group
Particle confinement processes are studied in detail on the Large Helical Device (LHD). Diffusion coefficients (D) and convection velocities (V) are estimated from density modulation experiments. The magnetic configuration and collisionality are widely scanned in order to investigate parameter dependences of D and V. To study the effect of the magn…
Published2009
G P Maddison A E Hubbard J W Hughes J A Snipes B Labombard I M Nunes M N A Beurskens S K Erents M A H Kempenaars B Alper S D Pinches M Valovic R Pasqualotto A Alfier E Giovannozzi JET EFDA Contributors
Experiments on the Alcator C-Mod and JET tokamaks with identical values of nondimensional variables at the pedestal top are expected to have the same local plasma transport for a ratio > 4 in absolute size and thus can help to clarify other effects in pedestal formation. At the high and low fields (7.9 T, 1.4 T respectively) involved, natural-densi…
Published2009
S. Chiesa P. M. Derlet S. L. Dudarev
The stability of interstitial defect and dislocation structures in bcc Fe as a function of temperature is believed to play a crucial role in determining defect evolution under irradiation conditions. The vibrational properties of defects constitute one contribution to the corresponding energetics and much work has been done within the harmonic appr…
Published2009
Yueqiang Liu I. T. Chapman, M. S. Chu, H. Reimerdes, F. Villone, R. Albanese, G. Ambrosino, A. M. Garofalo, C. G. Gimblett, R. J. Hastie, T. C. Hender, G. L. Jackson, R. J. La Haye, M. Okabayashi, A. Pironti, A. Portone, G. Rubinacci and E. J. Strait
Self-consistent computations are carried out to study the stability of the resistive wall mode RWM in DIII-D J. L. Luxon, Nucl. Fusion 42 , 614 2002 plasmas with slow plasma rotation, using the hybrid kinetic-magnetohydrodynamic code MARS-K [Y. Q. Liu and et al. , Phys. Plasmas 15 , 112503 (2008)]. Based on kinetic resonances between the mode and t…
Published2009
M. James H.R. Wilson J.W. Connor
The formation of neoclassical tearing modes (NTMs) severely limits the performance of a tokamak plasma by increasing the radial particle and heat fluxes from the core and can even lead to a plasma disruption. Indeed, NTMs are a serious consideration for the next step device, ITER. The appearance of a finite NTM magnetic island requires an initial â…
Published2009
S. Khakshouri D. M. Duffy
Tungsten is a strong contender for a plasma-facing material in future fusion power plant designs, and the material of choice for the divertor of ITER, due to its high melting point, thermal conductivity, and resistance to sputtering erosion. Sputtering erosion is a major concern for plasma-facing materials because sputtered atoms could enter the pl…
Published2009
C. T. Holcomb
Recent studies on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42 , 614 (2002)] have elucidated key aspects of the dependence of stability, confinement, and density control on the plasma magnetic configuration, leading to the demonstration of nearly noninductive operation for 1 s with pressure 30% above the ideal no-wall stability limit. Achieving…
Published2009
E. Surrey A. J. T. Holmes T. T. C. Jones
Abstract: The effect of beam generated plasma in the channels of the ITER electrostatic residual ion dump (ERID) is investigated. The space charge due to the plasma and the separating positive and negative ion beams could cause the ERID to fail if the plasma density is sufficiently high. The gas density at which this occurs is derived for both the …
Published2009