Gyrokinetic studies of trapped electron mode turbulence in the Helically Symmetric eXperiment stellarator

• DOI: 10.1063/1.4926510
• Publication Date: 2015-07-16T13:41:26Z
• Authors: B. J. Faber; M. J. Pueschel; J. H. E. Proll; P. Xanthopoulos; P. W. Terry; C. C. Hegna; G. M. Weir; K. M. Likin; J. N. Talmadge
• Keywords: Microturbulence; Wavenumber; Electron temperature; Gyrokinetics; Shearing (physics)

Gyrokinetic simulations of plasma microturbulence in the Helically Symmetric eXperiment are presented. Using profiles relevant to experimental operation, four dominant drift wave regimes observed ion wavenumber range, which identified as different flavors density-gradient-driven trapped electron modes. For most part, heat transport exhibits properties associated with turbulence driven by these types Additionally, long-wavelength, radially localized, nonlinearly excited coherent structures near resonant central flux surface, not predicted linear simulations, can further enhance levels. Integrated fluxes compatible observations corresponding density gradient range. Despite low shearing rates, zonal flows regulate but be overwhelmed at higher gradients long-wavelength structures.