C.J. Ham J.W. Connor S.C. Cowley R.J. Hastie T.C. Hender Y.Q. Liu
Calculations of tearing mode stability in tokamaks split conveniently into an external region, where marginally stable ideal MHD is applicable, and a resonant layer around the rational surface where sophisticated kinetic physics is needed. These two regions are coupled by the stability parameter △'. Pressure and current perturbations local…
PublishedA. Kirk I.T. Chapman T.E. Evans C. Ham J.R. Harrison G. Huijsmans Y. Liang Y.Q. Liu A. Loarte W. Suttrop A.J. Thornton
All current estimations of the energy released by type I ELMs indicate that, in order to ensure an adequate lifetime of the divertor targets on ITER, a mechanism is required to decrease the amount of energy released by an ELM, or to eliminate ELMs altogether. One such amelioration mechanism relies on perturbing the magnetic field in the edge plasma…
PublishedA.Kirk I.T. Chapman Yueqiang Liu P. Cahyna P. Denner G. Fishpool C.J. Ham J.R. Harrison Yunfeng Liang E. Nardon S. Saarelma R. Scannell A.J. Thornton The Mast Team
Sustained ELM mitigation has been achieved using RMPs with a toroidal mode number of n=4 and n=6 in lower single null and with n=3 in connected double null plasmas on MAST. The ELM frequency increases by up to a factor of eight with a similar reduction in ELM energy loss. A threshold current for ELM mitigation is observed above which the ELM freque…
PublishedI. 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…
PublishedI.T. Chapman W.A. Cooper A. Kirk C.J. Ham J.R. Harrison A. Patel S.D. Pinches R. Scannell A.J. Thornton The Mast Team
The distortion of the plasma boundary when three-dimensional resonant magnetic perturbations are applied has been measured in MAST H-mode plasmas. When the n = 3 resonant magnetic perturbations are applied to control edge localised modes, the plasma experiences a strong toroidal corrugation. The displacement of the plasma boundary is measured at va…
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…
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…
PublishedC J Ham C G Gimblett S E Penington
It is well known that stabilization of the resistive wall mode (RWM) may allow fusion power to be significantly increased for a given magnetic field in advanced tokamak operation. The principle of stabilization of the RWM by rotation has been established both experimentally and theoretically. Recent experimental results have indicated stabilization…
Published