The recent progress of thermonuclear fusion research based on the magnetic confinement of high-temperature plasmas, as weil as the design ofthe first experi- mental fusion tokamak reactors, has demonstrated that the physical conditions at the plasma periphery playa decisive role in achieving, maintaining, and controlling the thermonuclear bUffi. Because it is an interface between the hot burning deute- rium-tritium plasma and the cold material walls ofthe reactor vessel, the boundary (or the edge) plasma has to fulfill many functions related to the protection of the reactor walls from the intense particle and power fluxes generated in the reactor burning zone, protection of the central plasma from contamination by nonhydro- genie wall impurities (which dilute the thermonuclear fuel and degrade the burn conditions), exhaust of the thermal plasma power and the reactor ash (thermalized helium), etc.
These functions of the boundary plasma can be accomplished by suitable modification of the configuration of the confining magnetic field in the edge region and by an appropriate use of the radiative and collisional properties of atomic, ionic, and molecular species present (or deliberatcly introduced) in the plasma edge region.