Gyrokinetic simulations of interplay between geodesic acoustic modes and trapped electron mode turbulence

Abstract

Radial electric field dynamics are studied in gyrokinetic full-f simulations of tokamak plasmas. Calculations use parameters similar to a TEXTOR L-mode discharge in the presence of a steep density gradient and dominating trapped electron mode turbulence in the edge pedestal of the plasma. Temperature, density gradient and ion species are varied to study the radial electric field fluctuations and their relationship with thermal transport. The dominant frequency of electric field oscillations is within the geodesic acoustic mode range, and their amplitude is found to be clearly correlated with transport across the parametric scan.