Effect of island overlap on edge localized mode suppression by resonant magnetic perturbations in DIII-D

Fenstermacher, M. E.; Evans, T. E.; Osborne, T. H.; Schaffer, M. J.; Aldan, M. P.; deGrassie, J. S.; Gohil, P.; Joseph, I.; Moyer, R. A.; Snyder, P. B.; Groebner, R. J.; Jakubowski, M.; Leonard, A. W.; Schmitz, O.
May 2008
Physics of Plasmas;May2008, Vol. 15 Issue 5, p056122
Academic Journal
Recent DIII-D [J. L. Luxon et al., Nucl. Fusion 43, 1813 (2003)] experiments show a correlation between the extent of overlap of magnetic islands induced in the edge plasma by perturbation coils and complete suppression of Type-I edge localized modes (ELMs) in plasmas with ITER-like electron pedestal collisionality νe*∼0.1, flux surface shape and low edge safety factor (q95≈3.6). With fixed amplitude n=3 resonant magnetic perturbation (RMP), ELM suppression is obtained only in a finite window in the edge safety factor (q95) consistent with maximizing the resonant component of the applied helical field. ELM suppression is obtained over an increasing range of q95 by either increasing the n=3 RMP strength, or by adding n=1 perturbations to “fill in” gaps between islands across the edge plasma. The suppression of Type-I ELMs correlates with a minimum width of the edge region having magnetic islands with Chirikov parameter >1.0, based on vacuum calculations of RMP mode components excluding the plasma response or rotational shielding. The fraction of vacuum magnetic field lines that are lost from the plasma, with connection length to the divertor targets comparable to an electron-ion collisional mean free path, increases throughout the island overlap region in the ELM suppressed case compared with the ELMing case.


Related Articles

  • Current drive by helicon waves. Paul, Manash Kumar; Bora, Dhiraj // Journal of Applied Physics;Jan2009, Vol. 105 Issue 1, p013305 

    Helicity in the dynamo field components of helicon wave is examined during the novel study of wave induced helicity current drive. Strong poloidal asymmetry in the wave magnetic field components is observed during helicon discharges formed in a toroidal vacuum chamber of small aspect ratio. High...

  • Nonperturbative phenomena in QCD at finite temperature in a magnetic field. Agasian, N. // Physics of Atomic Nuclei;Nov2008, Vol. 71 Issue 11, p1967 

    The norperturbative QCD vacuum at finite temperature in a external magnetic field is studied. Equations that relate nonperturbative QCD condensates at finite temperature to the thermodynamic pressure at T ≠ 0 and H ≠ 0 are obtained, and low-energy theorems are derived. The free...

  • Outward electron orbit extending to inward part of closed helical magnetic surfaces surrounded by shifted negative space potential. Himura, H.; Nakamura, K.; Masamune, S.; Isobe, M.; Shimizu, A. // Physics of Plasmas;Mar2010, Vol. 17 Issue 3, p032507 

    Outward electron orbits that extend to the inward part of a closed helical vacuum magnetic region are found in three-dimensional calculations, which take into account two experimental findings. The pitch angle of electrons in the stochastic magnetic region (SMR) is scattered considerably due to...

  • Toward a nonlinear theory of acceleration of charged particles in a linearly polarized EH-ubitron field. Krut�ko, O. B. // Technical Physics;Jan99, Vol. 44 Issue 1, p79 

    The motion of charged particles in a linearly polarized EH-ubitron field with sinusoidal time dependence of the variable component of the magnetic field is investigated. It is shown that, depending on the parameters of the system and the initial conditions of entry of the particle into the...

  • Particle Beam Polarization in Storage Rings Controlled by Longitudinal Magnetic Field. Silenko, A. Ya. // Technical Physics Letters;Mar2003, Vol. 29 Issue 3, p237 

    It is suggested to use a longitudinal magnetic field for changing the polarization of particles (electrons, positrons, muons) in the beam of a storage ring. The change from vertical to longitudinal polarization by single or multiple switching of the longitudinal field for a certain time interval...

  • Conservation Law for the Binormal Momentum in the Presence of Charge Drift in a Magnetic Field. Trubnikov, B. A. // Journal of Experimental & Theoretical Physics;Sep2000, Vol. 91 Issue 3, p479 

    It is well-known that the motion of a charged particle in a magnetic field is described by the drift approximation, in which it is assumed that the squared velocity of the particle and the magnetic moment of the Larmor circle are conserved. It is shown that to a first approximation a third...

  • Statistical description and transport in stochastic magnetic fields. Vanden Eijnden, E.; Balescu, R. // Physics of Plasmas;Mar1996, Vol. 3 Issue 3, p874 

    Presents the statistical description of particle motion in a stochastic magnetic field. Stochastic Liouville equation associated with equations of motion of a test particle; Probability distribution function of the system for magnetic fields and collisional processes; Influence on the...

  • Particle acceleration near X-type magnetic neutral lines. Deeg, Hans-Jörg; Borovsky, Joseph E.; Duric, Nebojsa // Physics of Fluids B: Plasma Physics;Sep91, Vol. 3 Issue 9, p2660 

    The behavior of charged particles near X-type magnetic neutral lines is investigated. The magnetic field is taken to be hyperbolic and time stationary, with a uniform electric field perpendicular to the magnetic field. The general properties of the orbits of noninteracting particles in that...

  • Stochastic particle diffusion in velocity space for a bumpy torus. Chen, G. L.; Owen, L. W.; Batchelor, D. B.; Hedrick, C. L. // Physics of Fluids (00319171);Mar85, Vol. 28 Issue 3, p883 

    Nonadiabatic changes of the magnetic moment μ in the ELMO Bumpy Torus-Scale (EBT-S) have been studied both analytically and numerically. Simple forms of Δ μ and gyrophase change were obtained, permitting the changes in these quantities to be studied using an iteration mapping. The...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics