Spectrum of Subcritical Turbulence in an Inhomogeneous Plasma

A spectrum of fully developed turbulence via subcritical excitation in an inhomogeneous plasma is obtained. The dressed-test-mode analysis is developed, in which a dielectric tensor containing renormalized transfer rates is solved. The energy spectrum of the form E(k_⊥) ∝ G₀k_⊥⁻³ is obtained in the energy-containing region. (G₀ denotes the driving, which is the product of the gradients of plasma pressure and magnetic field.) Turbulent kinetic energy, W ∝ G₀², and transport coefficient, χT ∝ G₀^3/2, are found to be nonlinear functions of G₀, which presents a typical example of nonlinear, nonequilibrium transport.