Diffusion of runaway electrons in TEXTOR-94

In the TEXTOR-94 tokamak, radial profiles of synchrotron radiation from relativistic runaway electrons have been measured. From these and measurements of the evolution of the radiation, a radial profile of the diffusion coefficient for the runaway electrons in the plasma core with W-r approximate to 25 MeV is derived. At half radius, D-r < 0.01 m(2) s(-1) is found. This result is compared with several other measurements of runaway diffusion coefficients derived mainly from runaway losses at the plasma edge.