MAGNETIC-FIELD LINE MAPPINGS FOR A TOKAMAK WITH ERGODIC LIMITERS

An ergodic magnetic limiter is a device whose main effect in a tokamak is to create a cold boundary layer of chaotic magnetic field lines. I n order to study its effect we have used two approaches, The first is a description of magnetic island formation through an analytical metho d to describe its dimensions, results being in accordance with numeric al Poincare maps for magnetic field lines. The second is a model which simulates the ergodic limiter action as a sequence of impulsive pertu rbations, enabling the derivation of analytical formulae for the Poinc are maps. Copyright (C) 1996 Elsevier Science Ltd.