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Title: A path to stable low-torque plasma operation in ITER with test blanket modules

New experiments in the low-torque ITER Q = 10 scenario on DIII-D demonstrate that n = 1 magnetic fields from a single row of ex-vessel control coils enable operation at ITER performance metrics in the presence of applied non-axisymmetric magnetic fields from a test blanket module (TBM) mock-up coil. With n = 1 compensation, operation below the ITER-equivalent injected torque is successful at three times the ITER equivalent toroidal magnetic field ripple for a pair of TBMs in one equatorial port, whereas the uncompensated TBM field leads to rotation collapse, loss of H-mode and plasma current disruption. In companion experiments at high plasma beta, where the n = 1 plasma response is enhanced, uncorrected TBM fields degrade energy confinement and the plasma angular momentum while increasing fast ion losses; however, disruptions are not routinely encountered owing to increased levels of injected neutral beam torque. In this regime, n = 1 field compensation leads to recovery of a dominant fraction of the TBM-induced plasma pressure and rotation degradation, and an 80% reduction in the heat load to the first wall. These results show that the n = 1 plasma response plays a dominant role in determining plasma stability, and that nmore » = 1 field compensation alone not only recovers most of the impact on plasma performance of the TBM, but also protects the first wall from potentially damaging heat flux. Despite these benefits, plasma rotation braking from the TBM fields cannot be fully recovered using standard error field control. Lastly, given the uncertainty in extrapolation of these results to the ITER configuration, it is prudent to design the TBMs with as low a ferromagnetic mass as possible without jeopardizing the TBM mission.« less
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  1. General Atomics, San Diego, CA (United States)
  2. ITER Organization, St. Paul-lez-Durance Cedex (France)
  3. Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland)
  4. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  5. Columbia Univ., New York, NY (United States)
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  7. General Atomics, San Diego, CA (United States); U.S. Dept. of Energy, Washington, D.C. (United States)
  8. Assoc. EURATOM-Tekes (Finland)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; SC-G903402; FG02-04ER54761; FC02-04ER54698; AC02-09CH11466
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 57; Journal Issue: 3; Journal ID: ISSN 0029-5515
IOP Science
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); USDOE Office of Nuclear Energy (NE)
Contributing Orgs:
General Atomics, San Diego, CA (United States); US DOE, Washington, DC (United States); ITER Org, Route Vinon Sur Verdon, St Paul Les Durance (France); Ecole Polytech Fed Lausanne, Lausanne, (Switzerland); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Columbia Univ, New York, NY (United States); Assoc EURATOM Tekes, Espoo (Finland).; ITER Organization, route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul-lez-Durance Cedex, France Ecole Polytechnique Federale de Lausanne (EPFL), CRPP, CH-1015 Lausanne, Switzerland Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA Princeton Plasma Physics Laboratory, PO Box 451, Princeton, NJ 08543-0451, USA Columbia University, New York, NY 10027, USA Association EURATOM-Tekes, VTT, FI-02044 VTT, Finland
Country of Publication:
United States
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; test blanket modules; error fields; ITER; DIII-D; diii-d; error-field; wall
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1335182; OSTI ID: 1372492; OSTI ID: 1399868