Three-dimensional equilibria and transport in RFX-mod: A description using stellarator tools

M. Gobbin, D. Bonfiglio, A. H. Boozer, A. W. Cooper, D. F. Escande, S. P. Hirshman, J. Lore, R. Lorenzini, L. Marrelli, P. Martin, E. Martines, B. Momo, N. Pomphrey, I. Predebon, M. E. Puiatti, R. Sanchez, G. Spizzo, D. A. Spong, D. Terranova

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

RFX-mod self-organized single helical axis (SHAx) states provide a unique opportunity to advance 3D fusion physics and establish a common knowledge basis in a parameter region not covered by stellarators and tokamaks. The VMEC code has been adapted to the reversed-field pinch (RFP) to model SHAx equilibria in fixed boundary mode with experimental measurements as constraint. The averaged particle diffusivity over the helical volume, estimated with the Monte Carlo code ORBIT, has a neoclassical-like dependence on collisionality and does not show the 1/ trend of un-optimized stellarators. In particular, the helical region boundary, corresponding to an electron transport barrier with zero magnetic shear and improved confinement, has been investigated using numerical codes common to the stellarator community. In fact, the DKES/PENTA codes have been applied to RFP for local neoclassical transport computations, including radial electric field, to estimate thermal diffusion coefficients in the barrier region for typical RFX-mod temperature and density profiles. A comparison with power balance estimates shows that residual chaos due to secondary tearing modes and small-scale turbulence still contribute to drive anomalous transport in the barrier region.

Original languageEnglish
Article number062505
JournalPhysics of Plasmas
Volume18
Issue number6
DOIs
StatePublished - Jun 2011

Funding

This work was supported by the European Communities under the Contract of Association between EURATOM/ENEA. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

FundersFunder number
European Neuroendocrine Association
H2020 Euratom

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