Energy transfer of trapped electron turbulence in tokamak fusion plasmas

Abstract

The first principle gyrokinetic simulations of trapped electron turbulence in tokamak fusion plasmas demonstrate the energy transfers from the most linearly unstable modes at high k_theta rho _isim 1 to intermediate k_theta via parametric decay process in a short period of linear-nonlinear transition phase. Dominant nonlinear wave-wave interactions occur near the mode rational surface msimeq nq. In fully nonlinear turbulence, inverse energy cascade occurs between a cutoff wave number k_c and k_theta rho _isim 1 with a power law scaling |phi (k_theta )|^2propto k^{-3}, while modes with k<k_c are suppressed. The numerical findings show fair agreement with both the weak turbulence theory and realistic experiments on Tore Supra tokamak.