Particle Diffusion in Toroidal Fusion Systems (Tokamak).

Abstract

The plasma transports in two different geometrical configurations are studied, wherein in a system having a cylindrically symmetric shape, the diffusion process is termed classical transport. The use of toroidal configuration leads to an enhanced level of transport known as neoclassical. The plasma collisionality produces different forms of diffusion. The fluid-like diffusion occurring in highly collisional plasma is known as Pfirsch-Schlutre diffusion. In low collisionality plasma, the trapped particle leads to the so-called banana diffusion. The ion thermal diffusivity  exceeds the electron thermal diffusivity  by a factor , which is a landmark of this collisional diffusion process. In this paper, the classical diffusion coefficient with random walk step is covered, and the neoclassical transport and the trapped particle diffusion are studied.