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Title: Quantify Plasma Response to Non-Axisymmetric (3D) Magnetic Fields in Tokamaks, Final Report for FES (Fusion Energy Sciences) FY2014 Joint Research Target

The goal of the 2014 Joint Research Target (JRT) has been to conduct experiments and analysis to investigate and quantify the response of tokamak plasmas to non-axisymmetric (3D) magnetic fields. Although tokamaks are conceptually axisymmetric devices, small asymmetries often result from inaccuracies in the manufacture and assembly of the magnet coils, or from nearby magnetized objects. In addition, non-axisymmetric fields may be deliberately applied for various purposes. Even at small amplitudes of order 10-4 of the main axisymmetric field, such “3D” fields can have profound impacts on the plasma performance. The effects are often detrimental (reduction of stabilizing plasma rotation, degradation of energy confinement, localized heat flux to the divertor, or excitation of instabilities) but may in some case be beneficial (maintenance of rotation, or suppression of instabilities). In general, the magnetic response of the plasma alters the 3D field, so that the magnetic field configuration within the plasma is not simply the sum of the external 3D field and the original axisymmetric field. Typically the plasma response consists of a mixture of local screening of the external field by currents induced at resonant surfaces in the plasma, and amplification of the external field by stable kink modes. Thus, validatedmore » magnetohydrodynamic (MHD) models of the plasma response to 3D fields are crucial to the interpretation of existing experiments and the prediction of plasma performance in future devices. The non-axisymmetric coil sets available at each facility allow well-controlled studies of the response to external 3D fields. The work performed in support of the 2014 Joint Research Target has included joint modeling and analysis of existing experimental data, and collaboration on new experiments designed to address the goals of the JRT. A major focus of the work was validation of numerical models through quantitative comparison to experimental data, in order to gain confidence in their ability to predict the performance of ITER and other burning plasmas. An important element of this effort was also to verify experimentally the limits of validity of the models. The rest of this overview will summarize the key results of the work.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [1] ;  [4] ;  [2] ;  [1] ;  [1] ;  [2] ;  [3] ;  [2] ;  [1] ;  [1] ;  [2] ;  [6] ;  [2] ;  [4] ;  [2] more »;  [2] ;  [4] ;  [1] ;  [2] ;  [3] ;  [5] ;  [3] ;  [1] ;  [5] ;  [2] ;  [3] « less
  1. General Atomics, San Diego, CA (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Columbia Univ., New York, NY (United States)
  6. Culham Science Centre, Abingdon (United Kingdom). Euratom/CCFE Association
Publication Date:
OSTI Identifier:
1272458
DOE Contract Number:
FC02-04ER54698; AC02-09CH11466; FC02-99ER54512
Resource Type:
Technical Report
Research Org:
USDOE Office of Science (SC) (United States). Fusion Energy Sciences
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Contributing Orgs:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); General Atomics, San Diego, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ITER TOKAMAK; PLASMA; AMPLIFICATION; COORDINATED RESEARCH PROGRAMS; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; ROTATION; PERFORMANCE; COMPARATIVE EVALUATIONS; EXCITATION; PLASMA INSTABILITY; VALIDATION; MAGNETIC FIELD CONFIGURATIONS; EXPERIMENT DESIGN; HEAT FLUX; ASYMMETRY; PLASMA CONFINEMENT; ELECTRIC CURRENTS; FORECASTING; SIMULATION; KINK INSTABILITY; MATHEMATICAL MODELS