Probe measurements in the scrape-off layer of a Tokamak

Abstract

A Langmuir probe is used to study the plasma behaviour in the scrape-off layer of JFT-2a, (a Tokamak with an axisymmetric divertor). The measurements reveal particle fluxes to the divertor and the wall as well as cross-field profiles of density and potential in the scrape-off layer. On the basis of these measurements, the cross-field diffusion coefficient in the scrape-off layer and the divertor efficiency are estimated. The existence of the magnetic limiter is also verified by the method.