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Title: The three-dimensional modeling of plasma edge transport and divertor fluxes during application of resonant magnetic perturbations on ITER

Journal Article · · Nuclear Fusion
 [1];  [2];  [3];  [4];  [5];  [1];  [6];  [6];  [7];  [7];  [8];  [8];  [9];  [5];  [9];  [8];  [8];  [8]
  1. Univ. of Wisconsin, Madison, WI (United States)
  2. CEA/IRFM, Cadarache (France)
  3. IPP AS CR, Prague (Czech Republic)
  4. General Atomics, San Diego, CA (United States)
  5. Max Planck Institute for Plasma Physics, Greifswald (Germany)
  6. ITER Organization, Saint-Paul-lez-Durance (France)
  7. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  8. Institut fur Energieforschung - Plasmaphysik, Forschungszentrum, Julich (Germany)
  9. Fusion for Energy Joint Undertaking, Barcelona(Spain)

Results from three-dimensional modeling of plasma edge transport and plasma–wall interactions during application of resonant magnetic perturbation (RMP) fields for control of edge-localized modes in the ITER standard 15 MA Q = 10 H-mode are presented. The full 3D plasma fluid and kinetic neutral transport code EMC3-EIRENE is used for the modeling. Four characteristic perturbed magnetic topologies are considered and discussed with reference to the axisymmetric case without RMP fields. Two perturbation field amplitudes at full and half of the ITER ELM control coil current capability using the vacuum approximation are compared to a case including a strongly screening plasma response. In addition, a vacuum field case at high q95 = 4.2 featuring increased magnetic shear has been modeled. Formation of a three-dimensional plasma boundary is seen for all four perturbed magnetic topologies. The resonant field amplitudes and the effective radial magnetic field at the separatrix define the shape and extension of the 3D plasma boundary. Opening of the magnetic field lines from inside the separatrix establishes scrape-off layer-like channels of direct parallel particle and heat flux towards the divertor yielding a reduction of the main plasma thermal and particle confinement. This impact on confinement is most accentuated at full RMP current and is strongly reduced when screened RMP fields are considered, as well as for the reduced coil current cases. The divertor fluxes are redirected into a three-dimensional pattern of helical magnetic footprints on the divertor target tiles. At maximum perturbation strength, these fingers stretch out as far as 60 cm across the divertor targets, yielding heat flux spreading and the reduction of peak heat fluxes by 30%. However, at the same time substantial and highly localized heat fluxes reach divertor areas well outside of the axisymmetric heat flux decay profile. Reduced RMP amplitudes due to screening or reduced RMP coil current yield a reduction of the width of the divertor flux spreading to about 20–25 cm and cause increased peak heat fluxes back to values similar to those in the axisymmetric case. The dependencies of these features on the divertor recycling regime and the perpendicular transport assumptions, as well as toroidal averaged effects mimicking rotation of the RMP field, are discussed in the paper.

Research Organization:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA); University of Wisconsin
Grant/Contract Number:
AC52-07NA27344; GRT-055(PMS-PE); SC0013911
OSTI ID:
1871409
Alternate ID(s):
OSTI ID: 1252551
Report Number(s):
LLNL-JRNL-834535; 1051499; TRN: US2306750
Journal Information:
Nuclear Fusion, Vol. 56, Issue 6; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 59 works
Citation information provided by
Web of Science

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Cited By (4)

Screening of resonant magnetic perturbation fields by poloidally varying toroidal plasma rotation journal August 2018
Helical variation of density profiles and fluctuations in the tokamak pedestal with applied 3D fields and implications for confinement journal May 2018
Toroidal modeling of plasma response to RMP fields in ITER journal February 2017
Exploration of magnetic perturbation effects on advanced divertor configurations in NSTX-U journal June 2016