Observation of radial propagation of electrostatic fluctuations in the Saskatchewan torus-modified tokamak

Abstract

Radial propagation of electrostatic fluctuations in the edge region of the Saskatchewan torus-modified [W. Zhang et al., Phys. Fluids B 4, 3277 (1992)] tokamak has been measured using Langmuir probes. The propagation characteristics of the density fluctuations are analyzed by two point correlation techniques. A finite radial propagation speed is measured and is found to be a large fraction of the poloidal propagation speed. The speed of propagation is inversely proportional to the toroidal magnetic field, suggesting that the origin of these fluctuations could be drift wave type turbulence. The radial correlation length of turbulence is found to decrease with increasing magnetic field. The power averaged wave number shows an increase with increasing magnetic field, suggesting a decrease in the correlation lengths.