Publisher Summary This chapter discusses the design of the neutral beam (NB) system for the SST-1 machine. The design of the NB is based on a single 5 MW source beamline. The physical arrangement of the neutral beam injector system (NBIS) with the SST-1 machine is presented in the chapter. The plasma generator is a standard multipole bucket type source that operates in the emission limited discharge regime. Filament temperature of each of the 24 filaments is independently controlled. The main design issues of the power supply system for the NBIS are: long pulse operation of 1000 S, stringent quality requirement, integrated control, effects on the source 132 kV line, reliability, maintability, and effective cooling of the system. For the positive ion plasma source, AC filament heating supply is used. For long pulse operation, uniform heating of the filament length helps in the precise control of filament temperature and increases filament life. An integrated control for arc and filament system maintains the filament temperature for a given gas feed rate.