Ion temperature fluctuations in the ASDEX Upgrade scrape-off layer

Abstract

Abstract. The ion temperature in turbulent plasma filaments filiT is measured by a retarding field analyzer during L-mode discharges in the ASDEX Upgrade tokamak. At 2 cm outside the separatrix 11080−≈filiT eV, which is 3-4 times that of the background ions and 50-70 % of the ion temperature at the separatrix. filiT is reproduced by a fluid model of the parallel filament transport assuming the radial filament propagation speed of 400–1000 m s-1 in the near scrape-off layer, consistent with earlier experimental estimates. The conditional sampling used in experiment to measure filiT is tested on artificial time series obtained from a gyrofluid turbulence simulation.