Locality and universality in gyrokinetic turbulence

The nature of nonlinear interactions in gyrokinetic (GK) turbulence, driven by the ion-temperature gradient instability, is investigated using direct numerical simulations in toroidal flux tube geometry. To account for the level of separation existing between scales involved in an energetic interaction, the degree of locality of the free energy scale flux is analyzed employing Kraichnan s infrared (IR) and ultraviolet locality functions. Due to the nontrivial dissipative nature of GK turbulence, an asymptotic level for the locality exponents, indicative of a universal dynamical regime for GK s, is not recovered and an accentuated non-local behavior of the IR interactions is found instead, in spite of the local energy cascade observed.