Showing 991 - 1000 of 1684 Journals Results
2012
T. O’Gorman G. Naylor K. J. Gibson B. Huang G. J. Mcardle et al.
A real-time system has been developed to trigger both the MAST Thomson scattering (TS) system and the plasma control system on the phase and amplitude of neoclassical tearing modes (NTMs), extending the capabilities of the original system. This triggering system determines the phase and amplitude of a given NTM using magnetic coils at different tor…
Published2012
W.Fundamenski T.Eich D.Moulton F.Militello C.Lowry G.Maddison E.Havlickova D.Ward R.Kemp M.Wischmeier D.C.Mcdonald
Recent infra-red measurements of divertor power loads on JET and AUG [1], revealed that the inter-ELM power width at the outer mid-plane in attached ELMy H-modes does not exhibit any noticeable scaling with machine size [1]. Making use of these results to calculate the effective radial heat diffusivity, and then including this in parametrized expre…
Published2012
Pui-Wai Ma S. L. Dudarev
We develop a generalized Langevin spin dynamics (GLSD) algorithm where both the longitudinal and transverse (rotational) degrees of freedom of atomic magnetic moments are treated as dynamic variables. This removes the fundamental limitation associated with the use of stochastic Landau-Lifshitz (sLL) equations, in which the magnitude of magnetic mom…
Published2012
Pui-Wai Ma W. C. Liu C. H. Woo S. L. Dudarev
We perform large-scale molecular dynamics simulations to study the magnetic properties of amorphous iron under pressure. Simulations, exceeding by at least two orders of magnitude those accessible to density functional calculations, use the recently developed magnetic interatomic potential for iron. The distributions of the size of atomic magnetic …
Published2012
Z. R. Wang S. C. Guo Y. Q. Liu
The physics of kinetic effects on the resistive wall mode (RWM) stability is studied, and a comparison between reversed field pinch (RFP) and Tokamak configurations is made. The toroidal, magnetohydrodynamic (MHD)-kinetic hybrid stability code MARS-K, in which the drift kinetic effects are self-consistently incorporated into the MHD formulation, is…
Published2012
A. Kirk J. Harrison Yueqiang Liu E. Nardon I. T. Chapman P. Denner The Mast Team
The application of nonaxisymmetric resonant magnetic perturbations (RMPs) with a toroidal mode number n . 6 in the MAST tokamak produces a significant reduction in plasma energy loss associated with type-I edge localized modes (ELMs), the first such observation with n>3 . During the ELM mitigated stage clear lobe structures are observed in visible-…
Published2012
S. Saarelma P. Hill A. Bottino G. Colyer A.R. Field B. Mcmillan A. Peeters C.M. Roach Mast Team
Electrostatic gyrokinetic analyses are presented for an L-mode discharge with an internal transport barrier, from the spherical tokamak, MAST. Local and global microstability analysis finds similar linear growth rates for ion temperature gradient (ITG) driven modes. When the electron response is assumed to be adiabatic, growth rates are found to be…
Published2012
G. T. Von Nessi M. J. Hole J. Svensson L. Appel
In this paper, current profiles for plasma discharges on the mega-ampere spherical tokamak are directly calculated from pickup coil, flux loop, and motional-Stark effect observations via methods based in the statistical theory of Bayesian analysis. By representing toroidal plasma current as a series of axisymmetric current beams with rectangular cr…
Published2012
W. Fundamenski F. Militello D. Moulton D.C. Mcdonald
A new model of the L–H transition in tokamaks is proposed, based on the criterion that the transition occurs when plasma turbulence and shear Alfvén waves compete in the vicinity of the last-closed flux surface. The model is used to predict the scaling of the H-mode access power, PL–H, with magnetic and plasma variables. The predictio…
Published2012