Relating nondimensional scaling of microturbulence to global confinement and transport

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 (β, ν*, κ, q, Te/Ti ...) are held nearly constant. The turbulence is measured by examining the correlation properties of the local long-wavelength (kperpendicularρI≤1) density fluctuations, measured with beam emission spectroscopy. The radial correlation length of the turbulence, Lc,r, is shown to scale with the local ion gyroradius, with Lc,r∼5ρI while the decorrelation times scale with the local acoustic velocity as τc∼a/cs. The turbulent diffusivity parameter, D∼(Lc,r2/τc), 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 modeling compare reasonably well. (author)