Title: Integrated fusion simulation with self-consistent core-pedestal coupling

Abstract

Accurate predictions of fusion performance requires including the strong interplay that exists between core transport, pedestal structure, current profile and plasma equilibrium. An integrated modeling workflow capable of finding the steady-state self-consistent solution to this strongly coupled problem has been developed. The workflow, leverages first principles calculations and does not require prior knowledge of the kinetic profiles. Validation against DIII-D discharges shows that the workflow is capable of robustly predicting the kinetic profiles (electron and ion temperature and electron density) from the axis to the separatrix in agreement with the experiments. Results of a self-consistent optimization of the 15 MA D-T ITER baseline scenario show that controlling the pedestal density and impurity content during ITER operations will be critical to achieve high fusion performance while satisfying the requirements imposed by the density-limit. Further, we developed two neural-network (NN) based models as a means to perform a non-linear multivariate regression of theory-based models for the core transport fluxes, as well as for the pedestal structure. Specifically, we find that a NN-based approach can be used to consistently reproduce the results of the TGLF and EPED1 theory-based models over a broad range of plasma regimes, and with a computational speedup of severalmore » orders of magnitudes. The coupled core-pedestal workflow using these NN-accelerated models has been validated against a large database of DIII-D discharges, showing overall excellent agreement and performance. The NN paradigm is capable of breaking the speed-accuracy tradeoff that is expected of traditional numerical models, and can provide the missing link towards self-consistent coupled core-pedestal WDM simulations that are physically accurate and yet take only seconds to run.« less

Authors:

Meneghini, O. ^[1]; Snyder, P. B. ^[1]; Smith, S. P. ^[1]; Candy, J. ^[1]; Staebler, G. M.  ^[1];

• Search DOE PAGES for author "Staebler, G. M."
• Search DOE PAGES for ORCID "0000-0002-1944-1733"

Belli, E. A.  ^[1];

• Search DOE PAGES for author "Belli, E. A."
• Search DOE PAGES for ORCID "0000-0001-7947-2841"

Lao, L. L. ^[1]; Park, J. M. ^[2]; Green, D. L. ^[2]; Elwasif, W.  ^[2];

• Search DOE PAGES for author "Elwasif, W."
• Search DOE PAGES for ORCID "0000-0003-0554-1036"

Grierson, B. A. ^[3]; Holland, C. ^[4]

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+ Show Author Affiliations

1. General Atomics, San Diego, CA (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
4. Univ. of California, San Diego, CA (United States)

Publication Date:

Wed Apr 20 00:00:00 EDT 2016

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1319224

Alternate Identifier(s):

OSTI ID: 1248239; OSTI ID: 1372261; OSTI ID: 1489411

Grant/Contract Number:  

AC05-00OR22725; FC02-06ER54873; AC02-05CH11231; FC02-04ER54698; FG02-95ER54309; SC0012633; SC0012656

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Plasmas

Additional Journal Information:

Journal Volume: 23; Journal Issue: 4; Journal ID: ISSN 1070-664X

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasma transport properties; turbulence simulations; turbulent transport processes; plasma pressure; plasma temperature