IMPURITY PARTICLE TRANSPORT WITH RADIAL ELECTRIC FIELD AND PLASMA ROTATION IN JET OPTIMISED SHEAR PLASMAS

JET Optimised Shear (OS) experiments have produced internal thermal transport barriers (ITB) [1] which clearly show up in the plasma density and temperature profiles. This paper studies the influence of an ITB on impurity transport in JET OS plasmas. Two species are studied: intrinsic carbon and injected nickel as a trace impurity. The possible relation of particle transport to pressure gradient ∇Pi , radial electric field Er , and toroidal and poloidal rotation velocities Vφ and Vθ is investigated. We take two plasmas as examples which represent two groups of discharges with strong and weak transport barriers. Figure 1 shows the gradients in ion temperature and toroidal rotation profiles in these two OS discharges with different strength of ITB.