Edge Plasma Turbulence: Experiment

This talk will survey past and present experiments on edge plasma turbulence with an emphasis on recent results from toroidal fusion devices. This turbulence mainly consists of broadband plasma density fluctuations with relative amplitude ∼ 5-50% in the frequency range ∼ 10 kHz-1 MHz, with a size scale ∼ 0.1-10 cm perpendicular to the magnetic field but many meters along the magnetic field (nearly 2D '' filaments ''). Standard diagnostic methods will be described (electric and magnetic probes, electromagnetic scattering, microwave reflectometry, optical line emission, and heavy ion beam probes), and various data analysis techniques will be illustrated (1-point and 2-point statistical methods and 2D image analysis). Experimental results on edge turbulence will be reviewed in the following areas (time permitting): turbulence levels, frequency spectra, size scales, radial and poloidal variations, parameter scalings, intermittency and blobs, L-H transitions, relationship to edge flows, relationship to edge transport, and edge turbulence control. A comparison between various magnetic configurations will be attempted, and a comparison of the tokamak results to theory will be presented (from an experimental perspective). Finally, some possible directions for future measurements and experiments will be discussed. (author)