Non-dimensional scaling of turbulence characteristics and turbulent diffusivity

Plasma turbulence characteristics, including radial correlation lengths, decorrelation times, amplitude profile and flow velocity, have been measured during a ρ* scan on DIII-D while all other transport relevant dimensionless quantities (e.g., β, ν*, κ, q, T_e/T_i) are held nearly constant. The turbulence is measured by examining the correlation properties of the local long wavelength (k⊥ρ_i ≤ 1) density fluctuations, measured with beam emission spectroscopy. The radial correlation length of the turbulence L_c,r is shown to scale with the local ion gyroradius, L_c,r ≈ 5_ρi, while the decorrelation times scale with the local acoustic velocity as τ_c ∼ a/c_s. The turbulent diffusivity parameter, D ∼ (L_c, r²/τ_c), scales in a roughly gyro-Bohm-like fashion, as predicted by the gyrokinetic equations governing turbulent transport. The experimental one fluid power balance heat diffusivity scaling and that from GLF23 modelling compare reasonably well.