Energy transfer of trapped electron turbulence in tokamak fusion plasmas

Abstract

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