Space-time statistics of the turbulence in a tokamak edge plasma

Technical Report · Sun Jul 01 04:00:00 EDT 1984

OSTI ID:6339550

Levinson, S J; Beall, J M; Powers, Jr, E J; Bengtson, R D

The results of a study of the statistical space-time properties of the turbulence observed in the edge region of the PRETEXT Tokamak are reported. A local estimate of the wavenumber-frequency spectra S(k,..omega..) for poloidal (k/sub y/) and toroidal (k/sub z/) wavenumbers is determined for the range .5 cm/sup -1/ < k < 7.5 cm/sup -1/ for both potential and density fluctuations obtained from spatially fixed Langmuir probe pairs. The S(k/sub y/,..omega..) spectra are dominated by low frequencies (< 200 kHz) and small wavenumbers (< 3 cm/sup -1/) and appear broadened about an approximately linear statistical dispersion relation, anti k(..omega..). The broadening is characterized by a spectral width sigma/sub k/(..omega..) (rms deviation above anti k(..omega..)) which is of the order of anti k(..omega..). The turbulence appears to propagate poloidally with an apparent mean phase velocity of 1 to 2 x 10/sup 5/ cm/s in the ion diamagnetic drift direction. Measurements of the fluctuation-induced particle transport reveal the particle flux to be outward and resulting primarily from the low frequency, long wavelength components of the turbulence. A particle diffusion coefficient D/sub x/, estimated from measured particle flux and density profiles, is of the order of that estimated for Bohm diffusion, but appears to increase with density.

• Research Organization: Texas Univ., Austin (USA). Center for Fusion Engineering
• DOE Contract Number: AS05-77ET53042
• OSTI ID: 6339550
• Report Number(s): DOE/ET/53042-T1; ON: DE85002667
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700105* -- Fusion Energy-- Plasma Research-- Plasma Kinetics-Theoretical-- (-1987)
CLOSED PLASMA DEVICES
DIFFUSION
ELECTRIC PROBES
LANGMUIR PROBE
PLASMA DIAGNOSTICS
PLASMA SHEATH
PROBES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TURBULENCE