Helical core reconstruction of a DIII-D hybrid scenario tokamak discharge

Cianciosa, Mark; Wingen, Andreas; Hirshman, Steven P.; Seal, S. K.; Unterberg, Ezekial A.; Wilcox, Robert S.; Piovesan, Paolo; Lao, Lang; Turco, Francesca

doi:10.1088/1741-4326/aa6f82

Helical core reconstruction of a DIII-D hybrid scenario tokamak discharge

Journal Article · Thu May 18 00:00:00 EDT 2017 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/aa6f82· OSTI ID:1361308

Cianciosa, Mark ^[1]; Wingen, Andreas ^[1]; Hirshman, Steven P. ^[1]; Seal, S. K. ^[1]; Unterberg, Ezekial A. ^[1]; Wilcox, Robert S. ^[1]; Piovesan, Paolo ^[2]; Lao, Lang ^[3]; Turco, Francesca ^[4]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Consorzio RFX, Padova (Italy)
General Atomics, San Diego, CA (United States)
Columbia Univ., New York, NY (United States)

Our paper presents the first fully 3-dimensional (3D) equilibrium reconstruction of a helical core in a tokamak device. Using a new parallel implementation of the Variational Moments Equilibrium Code (PARVMEC) coupled to V3FIT, 3D reconstructions can be performed at resolutions necessary to produce helical states in nominally axisymmetric tokamak equilibria. In a flux pumping experiment performed on DIII-D, an external n=1 field was applied while a 3/2 neoclassical tearing mode was suppressed using ECCD. The externally applied field was rotated past a set of fixed diagnostics at a 20 Hz frequency. Furthermore, the modulation, were found to be strongest in the core SXR and MSE channels, indicates a localized rotating 3D structure locked in phase with the applied field. Signals from multiple time slices are converted to a virtual rotation of modeled diagnostics adding 3D signal information. In starting from an axisymmetric equilibrium reconstruction solution, the reconstructed broader current profile flattens the q-profile, resulting in an m=1, n=1 perturbation of the magnetic axis that is $$\sim 50\times $$ larger than the applied n=1 deformation of the edge. Error propagation confirms that the displacement of the axis is much larger than the uncertainty in the axis position validating the helical equilibrium.

View Accepted Manuscript (DOE)

Research Organization:: General Atomics, San Diego, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)

Sponsoring Organization:: DOE Office of Science; USDOE; USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)

Grant/Contract Number:: AC05-00OR22725; FC02-04ER54698; FG02-04ER54761

OSTI ID:: 1361308

Alternate ID(s):: OSTI ID: 1375929
OSTI ID: 22925782

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 7 Vol. 57; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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3D equilibrium reconstruction with islands Cianciosa, M.; Hirshman, S. P.; Seal, S. K. Plasma Physics and Controlled Fusion, Vol. 60, Issue 4 https://doi.org/10.1088/1361-6587/aaaf90	journal	March 2018
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Use of reconstructed 3D equilibria to determine onset conditions of helical cores in tokamaks for extrapolation to ITER Wingen, A.; Wilcox, R. S.; Seal, S. K. Nuclear Fusion, Vol. 58, Issue 3 https://doi.org/10.1088/1741-4326/aaa33d	journal	January 2018

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