Measurements of the cross-field diffusion coefficient Din the edge plasma of JET

Abstract
In relating the density scrape-off layer thickness lambda n to Dperpendicular to , account is taken of two aspects of the JET configuration: (a) the poloidally-varying cross-section of plasma flux tubes in the scrape-off layer, and (b) the different limiter configurations-discrete/continuous. Edge measurements of lambda n(0) in JET made by Langmuir probes and limiter-viewing cameras are used to deduce edge values of Dperpendicular to for ohmic discharges, over a range of conditions, Ip=1-5 MA, ne=0.7-6*1019 m-3. Generally the values are found to be close to Dperpendicular to =1019/ne m2 s-1, that is, Intor-Alcator scaling.