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Title: Effects of Complex Symmetry-Breakings on Alpha Particle Power Loads on First Wall Structures and Equilibrium in ITER

Abstract

Within the ITPA Topical Group on Energetic Particles, we have investigated the impact that various mechanisms breaking the tokamak axisymmetry can have on the fusion alpha particle confinement in ITER as well as on the wall power loads due to these alphas. In addition to the well-known TF ripple, the 3D effect due to ferromagnetic materials (in ferritic inserts and test blanket modules) and ELM mitigation coils are included in these mechanisms. ITER scenario 4 was chosen since, due to its lower plasma current, it is more vulnerable for various off-normal features. First, the validity of using a 2D equilibrium was investigated: a 3D equilibrium was reconstructed using the VMEC code, and it was verified that no 3D equilibrium reconstruction is needed but it is sufficient to add the vacuum field perturbations onto an axisymmetric equilibrium. Then the alpha particle confinement was studied using three independent codes, ASCOT, DELTA5D and F3D OFMC, all of which assume MHD quiescent background plasma and no anomalous diffusion. All the codes gave a loss power fraction of about 0.2%. The distribution of the peak power load was found to depend on the first wall shape. We also made the first attempt to accommodate themore » effect of fast-ion-related MHD on the wall loads in ITER using the HMGC and ASCOT codes. The power flux to the wall was found to increase due to the redistribution of fast ions by the MHD activity. Furthermore, the effect of the ELM mitigation field on the fast-ion confinement was addressed by simulating NBI ions with the F3D OFMC code. The loss power fraction of NBI ions was found to increase from 0.3% without the ELM mitigation field to 4-5% with the ELM mitigation field.« less

Authors:
 [1];  [2];  [3];  [2];  [1];  [4];  [5];  [2];  [5];  [6];  [7];  [8];  [1]
  1. Japan Atomic Energy Agency (JAEA), Naka
  2. Aalto University, Finland
  3. ORNL
  4. Max Planck Institute for Plasma Physics, Garching, Germany
  5. EURATOM / ENEA, Italy
  6. Max-Planck Institute, Garching, Germany
  7. Princeton Plasma Physics Laboratory (PPPL)
  8. ITER Organization, Cadarache, France
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1037088
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 51; Journal Issue: 6
Country of Publication:
United States
Language:
English

Citation Formats

Shinohara, K, Kurki-Suonio, T, Spong, Donald A, Asunta, O, Tani, K, Strumberger, E, Briguglio, S, Koskela, T, Vlad, G, Günter, S, Kramer, G, Putvinski, S, and Hamamatsu, K. Effects of Complex Symmetry-Breakings on Alpha Particle Power Loads on First Wall Structures and Equilibrium in ITER. United States: N. p., 2011. Web. doi:10.1088/0029-5515/51/6/063028.
Shinohara, K, Kurki-Suonio, T, Spong, Donald A, Asunta, O, Tani, K, Strumberger, E, Briguglio, S, Koskela, T, Vlad, G, Günter, S, Kramer, G, Putvinski, S, & Hamamatsu, K. Effects of Complex Symmetry-Breakings on Alpha Particle Power Loads on First Wall Structures and Equilibrium in ITER. United States. doi:10.1088/0029-5515/51/6/063028.
Shinohara, K, Kurki-Suonio, T, Spong, Donald A, Asunta, O, Tani, K, Strumberger, E, Briguglio, S, Koskela, T, Vlad, G, Günter, S, Kramer, G, Putvinski, S, and Hamamatsu, K. Sat . "Effects of Complex Symmetry-Breakings on Alpha Particle Power Loads on First Wall Structures and Equilibrium in ITER". United States. doi:10.1088/0029-5515/51/6/063028.
@article{osti_1037088,
title = {Effects of Complex Symmetry-Breakings on Alpha Particle Power Loads on First Wall Structures and Equilibrium in ITER},
author = {Shinohara, K and Kurki-Suonio, T and Spong, Donald A and Asunta, O and Tani, K and Strumberger, E and Briguglio, S and Koskela, T and Vlad, G and Günter, S and Kramer, G and Putvinski, S and Hamamatsu, K},
abstractNote = {Within the ITPA Topical Group on Energetic Particles, we have investigated the impact that various mechanisms breaking the tokamak axisymmetry can have on the fusion alpha particle confinement in ITER as well as on the wall power loads due to these alphas. In addition to the well-known TF ripple, the 3D effect due to ferromagnetic materials (in ferritic inserts and test blanket modules) and ELM mitigation coils are included in these mechanisms. ITER scenario 4 was chosen since, due to its lower plasma current, it is more vulnerable for various off-normal features. First, the validity of using a 2D equilibrium was investigated: a 3D equilibrium was reconstructed using the VMEC code, and it was verified that no 3D equilibrium reconstruction is needed but it is sufficient to add the vacuum field perturbations onto an axisymmetric equilibrium. Then the alpha particle confinement was studied using three independent codes, ASCOT, DELTA5D and F3D OFMC, all of which assume MHD quiescent background plasma and no anomalous diffusion. All the codes gave a loss power fraction of about 0.2%. The distribution of the peak power load was found to depend on the first wall shape. We also made the first attempt to accommodate the effect of fast-ion-related MHD on the wall loads in ITER using the HMGC and ASCOT codes. The power flux to the wall was found to increase due to the redistribution of fast ions by the MHD activity. Furthermore, the effect of the ELM mitigation field on the fast-ion confinement was addressed by simulating NBI ions with the F3D OFMC code. The loss power fraction of NBI ions was found to increase from 0.3% without the ELM mitigation field to 4-5% with the ELM mitigation field.},
doi = {10.1088/0029-5515/51/6/063028},
journal = {Nuclear Fusion},
number = 6,
volume = 51,
place = {United States},
year = {2011},
month = {1}
}