Linear ideal MHD predictions for n = 2 non-axisymmetric magnetic perturbations on DIII-D

An extensive examination of the plasma response to dominantly n = 2 non-axisymmetric magnetic perturbations (MPs) on the DIII-D tokamak shows the potential to control 3D field interactions by varying the poloidal spectrum of the radial magnetic field. The plasma response is calculated as a function of the applied magnetic field structure and plasma parameters, using the linear magnetohydrodynamic code MARS-F (Liu et al 2000 Phys. Plasmas 7 3681). The ideal, single fluid plasma response is decomposed into two main components: a local pitch-resonant response occurring at rational magnetic flux surfaces, and a global kink response. The efficiency with which the field couples to the total plasma response is determined by the safety factor and the structure of the applied field. In many cases, control of the applied field has a more significant effect than control of plasma parameters, which is of particular interest since it can be modified at will throughout a shot to achieve a desired effect. The presence of toroidal harmonics, other than the dominant n = 2 component, is examined revealing a significant n = 4 component in the perturbations applied by the DIII-D MP coils; however, modeling shows the plasma responses to n = 4 perturbations are substantially smaller than the dominant n = 2 responses in most situations.

[1]  M. Mauel,et al.  Dynamical plasma response of resistive wall modes to changing external magnetic perturbations , 2004 .

[2]  T. Osborne,et al.  Sustained suppression of type-I edge-localized modes with dominantly n = 2 magnetic fields in DIII-D , 2013 .

[3]  S. Saarelma,et al.  Modelling resonant field amplification due to low-n peeling modes in JET , 2010 .

[4]  I. Joseph,et al.  RMP enhanced transport and rotational screening in simulations of DIII-D plasmas , 2008 .

[5]  K. Burrell,et al.  Improved charge coupled device detectors for the edge charge exchange spectroscopy system on the DIII-D tokamak , 2001 .

[6]  J. S. deGrassie,et al.  RMP ELM suppression in DIII-D plasmas with ITER similar shapes and collisionalities , 2008 .

[7]  M E Fenstermacher,et al.  Suppression of large edge-localized modes in high-confinement DIII-D plasmas with a stochastic magnetic boundary. , 2004, Physical review letters.

[8]  A. Loarte,et al.  Screening of resonant magnetic perturbations by flows in tokamaks , 2012 .

[9]  T. Osborne,et al.  Resonant pedestal pressure reduction induced by a thermal transport enhancement due to stochastic magnetic boundary layers in high temperature plasmas. , 2009, Physical review letters.

[10]  Gerald A. Navratil,et al.  Suppression of resistive wall instabilities with distributed, independently controlled, active feedback coils , 2000 .

[11]  J. M. Bialek,et al.  Study of in-vessel nonaxisymmetric ELM suppression coil concepts for ITER , 2008 .

[12]  J. Scoville,et al.  Measurement of the resistive-wall-mode stability in a rotating plasma using active MHD spectroscopy. , 2004, Physical review letters.

[13]  Keith H. Burrell,et al.  Edge stability and transport control with resonant magnetic perturbations in collisionless tokamak plasmas , 2006 .

[14]  N Hawkes,et al.  Active control of type-I edge-localized modes with n=1 perturbation fields in the JET tokamak. , 2007, Physical review letters.

[15]  G. Huysmans,et al.  MHD stability in X-point geometry: simulation of ELMs , 2007 .

[16]  T. Osborne,et al.  Validation of the linear ideal magnetohydrodynamic model of three-dimensional tokamak equilibria , 2010 .

[17]  Bengt Lennartson,et al.  Feedback stabilization of nonaxisymmetric resistive wall modes in tokamaks. I. Electromagnetic model , 2000 .

[18]  J. Manickam,et al.  ELM destabilization by externally applied non-axisymmetric magnetic perturbations in NSTX , 2010 .

[19]  J. T. Scoville,et al.  Analysis and correction of intrinsic non-axisymmetric magnetic fields in high-β DIII-D plasmas , 2002 .

[20]  Yueqiang Liu,et al.  Toroidal modeling of plasma response and resonant magnetic perturbation field penetration , 2012 .

[21]  Effect of resonant magnetic perturbations with toroidal mode numbers of 4 and 6 on edge-localized modes in single null H-mode plasmas in MAST , 2013, 1305.3061.

[22]  C. Holcomb,et al.  Motional Stark effect diagnostic expansion on DIII-D for enhanced current and Er profile measurements , 2006 .

[23]  Yueqiang Liu,et al.  Full toroidal plasma response to externally applied nonaxisymmetric magnetic fields , 2010 .

[24]  G. L. Campbell,et al.  Design and operation of the multipulse Thomson scattering diagnostic on DIII‐D (invited) , 1992 .

[25]  D. A. Humphreys,et al.  CONTROL OF NEOCLASSICAL TEARING MODES IN DIII-D , 2001 .

[26]  M. Becoulet,et al.  Resonant magnetic perturbation experiments on MAST using external and internal coils for ELM control , 2010 .

[27]  A. Turnbull.  Plasma response models for non-axisymmetric perturbations , 2012 .

[28]  P. B. Snyder,et al.  The EPED pedestal model and edge localized mode-suppressed regimes: Studies of quiescent H-mode and development of a model for edge localized mode suppression via resonant magnetic perturbations , 2012 .

[29]  W. Park,et al.  Plasma simulation studies using multilevel physics models , 1999 .

[30]  G. Jackson,et al.  Effect of resonant and non-resonant magnetic braking on error field tolerance in high beta plasmas , 2009, Nuclear Fusion.

[31]  H. Koslowski,et al.  Strike point splitting induced by external magnetic perturbations: observations on JET and MAST and associated modelling , 2011 .

[32]  Yunfeng,et al.  Understanding ELM mitigation by resonant magnetic perturbations on MAST , 2012 .

[33]  A. Bondeson,et al.  The CHEASE code for toroidal MHD equilibria , 1996 .

[34]  G. Dif-Pradalier,et al.  Non-linear magnetohydrodynamic modeling of plasma response to resonant magnetic perturbations , 2013 .

[35]  A. M. Garofalo,et al.  Analysis of stable resistive wall modes in a rotating plasma , 2003 .

[36]  P T Lang,et al.  First observation of edge localized modes mitigation with resonant and nonresonant magnetic perturbations in ASDEX Upgrade. , 2011, Physical review letters.

[37]  Stephen C. Jardin,et al.  Calculations of two-fluid magnetohydrodynamic axisymmetric steady-states , 2009, J. Comput. Phys..

[38]  Jong-Kyu Park,et al.  Control of asymmetric magnetic perturbations in tokamaks. , 2007, Physical review letters.

[39]  V. Toigo,et al.  Design of in-vessel saddle coils for MHD control in ASDEX Upgrade , 2009 .

[40]  Steven J. Plimpton,et al.  The NIMROD code: a new approach to numerical plasma physics , 1999 .

[41]  S. Saarelma,et al.  Understanding edge-localized mode mitigation by resonant magnetic perturbations on MAST , 2013, 1306.4777.

[42]  L. L. LoDestro,et al.  CORSICA: A comprehensive simulation of toroidal magnetic-fusion devices. Final report to the LDRD Program , 1997 .

[43]  J. Manickam,et al.  Control of the resistive wall mode with internal coils in the DIII–D tokamak , 2005 .

[44]  S. G. Lee,et al.  Suppression of edge localized modes in high-confinement KSTAR plasmas by nonaxisymmetric magnetic perturbations. , 2012, Physical review letters.

[45]  R. L. Haye,et al.  Measurement and modeling of three-dimensional equilibria in DIII-D , 2011 .

[46]  S. Ku,et al.  Extended MHD simulation of resonant magnetic perturbations , 2009 .

[47]  L. Lao,et al.  MHD Equilibrium Reconstruction in the DIII-D Tokamak , 2005 .