K. G. McClements M. J. Hole
The transport of injected beam ions due to toroidal magnetic field ripple in the mega-ampere spherical tokamak (MAST) is quantified using a full orbit particle tracking code, with collisional slowing-down and pitch-angle scattering by electrons and bulk ions taken into account. It is shown that the level of ripple losses is generally rather low, al…
PublishedJ. H. E. Proll P. Helander J.W. Connor G. G. Plunk
It is shown that in perfectly quasi-isodynamic stellarators, trapped particles with a bounce frequency much higher than the frequency of the instability are stabilizing in the electrostatic and collisionless limit. The collisionless trapped-particle instability is therefore stable as well as the ordinary electron-densitygradient- driven trapped-ele…
PublishedT. 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…
PublishedW.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…
PublishedC. D. Warrick R. J. Buttery G. Cunningham S. J. Fielding T. C. Hender B. Lloyd A.W. Morris M. R. O’Brien T. Pinfold K. Stammers M. Valovic M. Walsh,* H. R. Wilson Compass-D Rf Teams
Lower hybrid current drive (LHCD) with modest powers ( 10% of the total power input) has been used for the first time to completely stabilize performance limiting neoclassical tearing modes in many COMPASS-D tokamak discharges. The stabilizing effect in these experiments is consistent with a reduction in the free energy available in the current pro…
PublishedPui-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 …
PublishedZ. 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…
PublishedA. 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-…
PublishedS. 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…
PublishedPui-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…
Published