Duoplasmatron type source with cold cathode

The duoplasmatron is widely used as a high-intensity ion source. The LINAC I-2, which is the injector of a 10 GeV PS, uses a duoplasmatron with a cold cathode. The initial cathode was a heated tantalum filament which was placed in a hollow tantalum cylinder with a wall thickness of 0.1--0.5 mm. It was subsequently discovered that it was not necessary to heat the filament in order to maintain the arc discharge and therefore the filament was used only for source bakeout. Now a thin-wall tantalum cylinder is used as the cathode. The cathode lasts up to 6000 h, requiring replacement approximately once a year