In Situ Regeneration of Fusion Reactor First Walls

The feasibility of in situ regeneration of a deuterium-tritium (D-T) fusion reactor first wall is explored. Chemical and physical vapor deposition processes are considered for applying low-Z materials and metals. Trial deposits of carbon, SiC, Si₃N₄, and (Si, Al)N were prepared by one or both of these fabrication techniques. Material properties such as chemical composition, impurity concentration, morphology, and crystal structure thought to be important in first wall performance were found to be controllable by the vapor deposition process conditions. Chemical composition of the gas mixtures, substrate temperature, and deposition pressures were parameters that influenced material properties in all vapor deposition processes. These parameters may be expected to be controllable in a D-T fusion reactor chamber. Temperature can be adjusted within the plasma zone by a glow discharge. The chemical composition of the reactant gases can be controllable by an auxiliary gas supply and exhaust systems. Gas pressure control within the reactor is a required feature of any fusion reactor system. In situ regeneration of the fusion first wall by vapor deposition processes thus appears feasible.