Simultaneous measurements of electron thermal and particle transport in JET

Radial electron thermal and particle diffusivities have been measured using transient methods yielding chi e and De simultaneously in the same spatial region in the plasma interior. Three methods have been applied, analysis of inward propagation of temperature and density perturbations caused by injection of a small pellet into the plasma, the outward propagation of electron temperature and density pulses caused by sawteeth, and thirdly time-dependent transport analysis applied to non-stationary plasmas. In Ohmically heated deuterium plasmas, limited by the outer carbon belt-limiters, the authors deduce chi e=2.9+or-0.4 m2 s-1 and De=0.4+or-0.2 m2 s-1, giving chi e/De=7.2+or-3. The large value of chi e/De would seem to exclude E*B convection as a dominant mechanism in the observed radial thermal transport in JET.