The plasma boundary region and the role of atomic and molecular processess

This chapter outlines the basic processes of plasma transport and plasma surface interactions and examines the atomic processes of particular relevance to the boundary region. Describes the incorporation of these basic processes into self-consistent models of the boundary region and gives some examples of the boundary conditions predicted. Discusses the magnetic topology of the plasma boundary; transport to the limiter surface of plasma particles and energy in the direction parallel to the magnetic field; properties of the plasma sheath; particle transport in a collisional boundary plasma; transport of plasma energy to the limiter; convective transport; modeling of the boundary plasma; divertors; plasma surface interactions; return of incident particles; physical sputtering; atomic processes in the boundary plasma; dissipation of electron energy due to collisions of electrons with ''hydrogen'' atoms; the influence of charge exchange and the recycling of H atoms; effects of molecular ''hydrogen''; the effects of electron collisions with impurity elements; interaction between the boundary and the confined plasma; and a radiatively cooled plasma edge. Finds that the boundary behavior has substantial impact upon the performance of a magnetic fusion device. Points out that an appreciation of the problems calls for a self-consistent interrelation of plasma transport, surface interactions and atomic processes