Chapter 2: Plasma confinement and transport

Physics knowledge in plasma confinement and transport relevant to design of a reactor-scale tokamak is reviewed and methodologies for projecting confi nement properties to ITER are provided. Theoretical approaches to describin g a turbulent plasma transport in a tokamak are outlined and phenomenology of major energy confinement regimes observed in tokamaks, including those w ith edge and internal transport barriers, is described. The chapter is focu sed on the energy confinement in the high confinement regime (H-mode) with the edge localized MHD modes, the basic operational regime of ITER. Three a pproaches are being pursued: (i) derivation of empirical global scaling law s; (ii) non-dimensionally similar studies; and (iii) one dimensional transp ort modelling codes, with the first approach recommended as the most robust at the present time. Special attention is paid to analysis of uncertaintie s in confinement predictions. Empirical scaling relations for projecting th e L-mode to H-mode power threshold based on re,regression analysis of an ex tensive database are discussed. Particle and toroidal momentum confinement and their relation to energy confinement are reviewed.