The radial propagation of electrostatic fluctuation is considered extremely important for understanding cross-field anomalous transport. In this paper, two arrays of Langmuir probes are used to analyze electrostatic fluctuations in the edge of IR-T1 tokamak plasma in both the radial and the poloidal directions. The propagation characteristics of the floating potential fluctuations are analyzed by the two-point correlation technique. The wavenumber spectrum shows that there is a net radially outward propagation of turbulent fluctuations in the edge and scrape-off layer (SOL) regions. Hence, edge turbulence presumably originates from core fluctuations.

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Tow pairs of poloidally spaced and radially movable Langmuir probes were used for measuring ion saturation current and floating potential in the edge plasma of IR-T1 Tokamak. Radial profile of the floating potential, it's gradient (−∇) , that is proportional to radial electric field Er ,and phase velocity of plasma fluctuations are determined. Results show that there is a naturally occurred velocity shear layer in the proximity of the last closed flux surface.