Abstract: A system for repairing a crack in a component, or forming a joint between two components, is described. The system includes a filler material; a plasma-generating material; and a ceramic cover that is positioned around the crack, or around an interface region between two components that are to be joined. The filler material is positioned proximate to the crack or the interface region; and the plasma generating material is positioned in the vicinity of the crack or the interface region. A microwave generator for generating a microwave field inside an enclosure region enclosed by the cover, and proximate to the crack or interface region, also forms part of the system. Related methods for filling at least one cavity in a casting component are also described.