An ion source has an arc chamber with a first end and a second end. A first cathode at the first end of the arc chamber has a first cathode body and a first filament disposed within the first cathode body. A second cathode at the second end of the arc chamber has a second cathode body and a second filament disposed within the second cathode body. A filament switch selectively electrically couples a filament power supply to each of the first filament and the second filament, respectively, based on a position of the filament switch. A controller controls the position of the filament switch to alternate the electrical coupling of the filament power supply between the first filament and the second filament for a plurality of switching cycles based on predetermined criteria. The predetermined criteria can be a duration of operation of the first filament and second filament.