J. R. Harrison A. Kirk I T. Chapman P. Cahyna Yueqiang Liu E. Nardon A.J. Thornton
Lobe structures due to the application of resonant magnetic perturbations (RMPs) have been observed using wide-angle imaging of light from He1+ ions in the vicinity of the lower X-point in MAST. The data presented are from lower single-null discharges where RMPs of toroidal mode number, n, of 4 and 6 were applied. It has been found that, above a th…
PublishedA. Kirk Yueqiang Liu I.T. Chapman J. Harrison E. Nardon R. Scannell A.J. Thornton The Mast Team
The application of resonant magnetic perturbations (RMPs) with a toroidal mode number of n=3 to connected double null plasmas in the MAST tokamak produces up to a factor of 9 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 which…
PublishedG. Z. Hao Y. Q. Liu A. K. Wang G. Matsunaga M. Okabayashi et al.
The kinetic effect of trapped energetic particles (EPs), arising from perpendicular neutral beam injection, on the stable low-n peeling modes in tokamak plasmas is investigated, through numerical solution of the mode’s dispersion relation derived from an energy principle. A resistive-wall peeling mode with m/n = 6/1, with m and n being the poloid…
PublishedA. D. Turnbull N. M. Ferraro V. A. Izzo E. A. Lazarus J.-K. Park W. A. Cooper S. P. Hirshman L. L. Lao M. J. Lanctot S. Lazerson Y. Q. Liu A. Reiman F. Turco
With the installation of non-axisymmetric coil systems on major tokamaks for the purpose of studying the prospects of ELM-free operation, understanding the plasma response to the applied fields is a crucial issue. Application of different response models, using standard tools, to DIII-D discharges with applied non-axisymmetric fields from internal …
PublishedYueqiang Liu A. Kirk Y. Sun
A toroidal, quasi-linear model is proposed to study the penetration dynamics of the resonant magnetic perturbation (RMP) field into the plasma. The model couples the linear, fluid plasma response to a toroidal momentum balance equation, which includes torques induced by both fluid electromagnetic force and by (kinetic) neoclassical toroidal viscous…
PublishedYueqiang Liu Youwen Sun
The non-linear interplay between the resistive wall mode (RWM) and the toroidal plasma flow is numerically investigated in a full toroidal geometry, by simultaneously solving the initial value problems for the n¼1 RW and the n¼0 toroidal force balance equation. Here, n is the toroidal mode number. The neoclassical toroidal viscous torque is ident…
PublishedC.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…
Published