Suppression of large edge localized modes in high confinement DIII-D plasmas with a stochastic magnetic boundary

Abstract Large 70 Hz Type-I edge localized modes (ELMs) are converted into small 130 Hz oscillations using edge resonant magnetic perturbations (RMPs) from a coil with currents ⩽0.4% Ip in double null DIII-D plasmas. When the RMP is properly phased with respect to the background field errors, all but a few isolated ELM-like events are suppressed. The impulsive pedestal energy loss ΔEELM/Δt1/2 to the scrape-of layer is reduced a factor of ⩾20 relative to the Type-I ELMs and the core confinement is unaffected by the perturbation field. Significant changes in the properties of the ELMs are also observed when edge RMPs are applied to lower single null plasmas but the nature of these changes are much more complex. Both lower single null and double null plasmas are being studied to determine how ELM control techniques based on the application of edge RMPs can be expected to scale to future devices such as ITER.

[1]  A. Loarte,et al.  Assessment of erosion of the ITER divertor targets during type I ELMs , 2003 .

[2]  Martin Jakobi,et al.  ELM frequency control by continuous small pellet injection in ASDEX upgrade , 2003 .

[3]  J. A. Leuer,et al.  Anomalies in the applied magnetic fields in DIII-D and their implications for the understanding of stability experiments , 2003 .

[4]  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.

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

[6]  M. Sugihara,et al.  Characteristics of type I ELM energy and particle losses in existing devices and their extrapolation to ITER , 2003 .

[7]  P. Barabaschi,et al.  Key ITER plasma edge and plasma–material interaction issues , 2003 .

[8]  T. Evans,et al.  MODELING OF COUPLED EDGE STOCHASTIC AND CORE RESONANT MAGNETIC FIELD EFFECTS IN DIVERTED TOKAMAKS , 2002 .

[9]  T. Petrie,et al.  ELM particle and energy transport in the SOL and divertor of DIII-D , 2003 .

[10]  P. Holmes,et al.  Nonlinear Oscillations, Dynamical Systems, and Bifurcations of Vector Fields , 1983, Applied Mathematical Sciences.

[11]  R. Budny,et al.  Improved ELM scaling with impurity seeding in JET , 2003 .

[12]  G. Saibene,et al.  Characteristics and scaling of energy and particle losses during Type I ELMs in JET H-modes , 2002 .

[13]  T. Evans,et al.  Explicit calculations of homoclinic tangles in tokamaks , 2003 .

[14]  J. Scoville,et al.  Design of a coil to correct magnetic field errors on the DIII-D tokamak , 1991, [Proceedings] The 14th IEEE/NPSS Symposium Fusion Engineering.

[15]  Lithium divertor concept and results of supporting experiments , 2002 .

[16]  P. Ghendrih,et al.  REVIEW ARTICLE: Theoretical and experimental investigations of stochastic boundaries in tokamaks , 1996 .

[17]  T. W. Petrie,et al.  ELM energy scaling in DIII-D , 2002 .

[18]  T. Evans,et al.  Homoclinic tangles, bifurcations and edge stochasticity in diverted tokamaks , 2003 .

[19]  T. Evans,et al.  Modeling of stochastic magnetic flux loss from the edge of a poloidally diverted tokamak , 2002 .