A light source system, preferably including one or more electron inputs, splitters, recombiners, and/or electron outputs, and optionally including one or more accelerator modules, input transports, radiator modules, and/or output transports. The system can optionally include one or more ancillary elements (e.g., electron optics elements). A method of operation, preferably including operating in a normal mode and/or operating in a backup mode.