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Title: Validation of transport models using additive flux minimization technique

A new additive flux minimization technique is proposed for carrying out the verification and validation (V and V) of anomalous transport models. In this approach, the plasma profiles are computed in time dependent predictive simulations in which an additional effective diffusivity is varied. The goal is to obtain an optimal match between the computed and experimental profile. This new technique has several advantages over traditional V and V methods for transport models in tokamaks and takes advantage of uncertainty quantification methods developed by the applied math community. As a demonstration of its efficiency, the technique is applied to the hypothesis that the paleoclassical density transport dominates in the plasma edge region in DIII-D tokamak discharges. A simplified version of the paleoclassical model that utilizes the Spitzer resistivity for the parallel neoclassical resistivity and neglects the trapped particle effects is tested in this paper. It is shown that a contribution to density transport, in addition to the paleoclassical density transport, is needed in order to describe the experimental profiles. It is found that more additional diffusivity is needed at the top of the H-mode pedestal, and almost no additional diffusivity is needed at the pedestal bottom. The implementation of this Vmore » and V technique uses the FACETS::Core transport solver and the DAKOTA toolkit for design optimization and uncertainty quantification. The FACETS::Core solver is used for advancing the plasma density profiles. The DAKOTA toolkit is used for the optimization of plasma profiles and the computation of the additional diffusivity that is required for the predicted density profile to match the experimental profile.« less
Authors:
;  [1] ;  [2] ;  [3] ; ;  [4]
  1. Tech-X Corporation, 5621 Arapahoe Ave., Boulder, Colorado 80303 (United States)
  2. General Atomics, San Diego, California 92121 (United States)
  3. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States)
  4. Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)
Publication Date:
OSTI Identifier:
22218526
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 10; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BOUNDARY LAYERS; CALCULATION METHODS; CHARGED-PARTICLE TRANSPORT; D CODES; DOUBLET-3 DEVICE; F CODES; H-MODE PLASMA CONFINEMENT; NEOCLASSICAL TRANSPORT THEORY; PLASMA DENSITY; PLASMA RADIAL PROFILES; PLASMA SIMULATION; TIME DEPENDENCE; TRAPPING; VALIDATION