Flow profile measurement with a rotating Mach probe in the scrape-off layer of the JFT-2M tokamak

The ion flow velocity profile of the JFT-2M scrape-off layer (SOL) plasma has been measured with a rotating Mach probe. It is found that the parallel flow (about 20 km s−1 in the same direction as the plasma current) is dominant at the outer mid-plane of the SOL. Although the parallel-perpendicular flows are affected by the radial electric field made by divertor biasing, the SOL plasma tends to rotate always toroidally with very small shear.