Kinetic theory of plasma in the limiter-scrape-off layer

Abstract

An asymptotic solution is given for the ion-drift-kinetic equation with a full Fokker–Planck term for the limiter-scrape-off layer in a tokamak. In this layer, the plasma is assumed to consist of hot, collisionless ions, and cold, collisional electrons. From the solution of the boundary-layer problem, ion and electron particle and energy losses to the limiter are calculated. Limiter load profiles due to ions are explicitly given as functions of the poloidal angle.

Effect of anomalous transport on plasma convection in the poloidal limiter shadow of a tokamak

“…[ 1 ] differs, in particular, from the kinetic model given in Ref. [7]. From the very beginning, in Ref.…”

“…By substituting the expressions for the total fluxes in the continuity equations and integrating them along the field line sections with allowance for the boundary conditions, we obtain the equations for the relative density u = ln(n/n a ) and potential <p* = e^/T a , which are generalizations of Eqs (7) and (3) of Ref. [1], respectively:…”

“…where T Q and n Q are the ion and electron temperature a a and density at the internal boundary of the limiter layer for r = a; q is the safety factor; c is the speed of light. Equations ( 1) and (2) differ from Eqs (7) and (3) of Ref. [1] in that (a)VT f andVT £ terms are added to the ion and electron diamagnetic drifts; (b) the spatial dependence of the sound speed is included; (c) DAn is added to the continuity equations.…”

“…This was also done in Ref. [ 1 ] in solving Eqs (7) and (3). In what follows we also use a continuity equation for the electrons which is a combination of Eqs ( 1) and ( 2…”

Impurity transport calculations for the limiter shadow region of a tokamak

“…Thus, plasma transport and impurity sources at the walls become de-coupled from impurity transport. Although attempts have been made to solve the plasma transport problem in the scrape-off layer on the basis of the usual drift-kinetic equations [3][4][5][6] -there are papers, NUCLEAR FUSION, Vol.21, No. 5 (1981) which explicitly take account of high mass velocities in the drift-kinetic equations [7,8] -a self-consistent solution for the scrape-off layer plasma is still missing.…”