Chapter 2: Plasma confinement and transport

TLDR

Theoretical approaches to turbulent plasma transport in tokamaks and the phenomenology of major energy confinement regimes, including edge and internal transport barriers, are outlined, and particle and toroidal momentum confinement and their relation to energy confinement are reviewed. The chapter reviews physics knowledge relevant to reactor‑scale tokamak design, projects confinement properties to ITER, focuses on H‑mode energy confinement with edge‑localized MHD modes, and emphasizes uncertainty analysis in confinement predictions. The authors review plasma confinement physics, outline theoretical turbulent transport approaches, and employ three main methods—empirical global scaling laws, non‑dimensional similarity studies, and one‑dimensional transport codes—with empirical scaling relations for L‑ to H‑mode power thresholds highlighted as the most robust. Empirical scaling relations for projecting the L‑mode to H‑mode power threshold based on regression analysis of an extensive database are discussed.

Abstract

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