I. T. Chapman A. Kirk C. J. Ham J. R. Harrison Y. Q. Liu et al.
Type-I Edge Localised Modes (ELMs) have been mitigated in MAST through the application of n = 3, 4, and 6 resonant magnetic perturbations. For each toroidal mode number of the non-axisymmetric applied fields, the frequency of the ELMs has been increased significantly, and the peak heat flux on the divertor plates reduced commensurately. This increa…
PublishedYueqiang Liu J. W. Connor S. C. Cowley C. J. Ham R. J. Hastie et al.
A numerical study is carried out, based on a simple toroidal tokamak equilibrium, to demonstrate the radial re-distribution of the electromagnetic torque density, as a result of a rotating resistive plasma (linear) response to a static resonant magnetic perturbation field. The computed electromagnetic torque peaks at several radial locations even i…
PublishedYueqiang Liu R. J. Hastie T. C. Hender
Two possible ways of modifying the linear tearing mode index, by active magnetic feedback and by drift kinetic effects of deeply trapped particles, are analytically investigated. Magnetic feedback schemes, studied in this work, are found generally stabilizing for Δ′. The drift kinetic effects from both thermal particles and hot ions tend to redu…
PublishedA. Kirk I.T. Chapman J. Harrison Yueqiang Liu E. Nardon S. Saarelma R. Scannell A.J. Thornton The Mast Team
The application of resonant magnetic perturbations (RMPs) with a toroidal mode number of n=4 or n=6 to lower single null plasmas in the MAST tokamak produces up to a factor of 5 increase in Edge Localized Mode (ELM) frequency and reduction in plasma energy loss associated with type-I ELMs. A threshold current for ELM mitigation is observed above wh…
PublishedC.J. Ham Y.Q. Liu J.W. Connor S.C. Cowley R.J. Hastie T.C. Hender T.J. Martin
Two methods for calculating tearing mode stability are described in this paper. A fast method using the recently improved T7 code (Ham et al. 2012 Plasma Phys. Control. Fusion 54 025009) and a new method based on the MARS-F MHD stability code (Liu et al. 2000 Phys. Plasmas 7 3681) which constructs the tearing mode solution from calculated basis fun…
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-…
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…
PublishedYueqiang Liu J. W. Connor S. C. Cowley C. J. Ham R. J. Hastie et al.
Within the single fluid theory for a toroidal, resistive plasma, the favorable average curvature effect [Glasser et al. , Phys. Fluids 18 , 875 (1975)], which is responsible for the strong stabilization of the classical tearing mode at finite pressure, can also introduce a strong screening effect to the externally applied resonant magnetic field. C…
PublishedR. J. Buttery A. H. Boozer Y. Q. Liu J.-K. Park N. M. Ferraro
Significant progress has been made in interpreting the effects of non-axisymmetric “error” fields on a plasma through ideal MHD stability and a dominant “least stable” ideal mode through which the fields couple to the tearing resonant surface. However, in contrast to expectations from such theories, experiments have found limited success in…
Published