Abstract: A proposed indirect heated cathode has an inner tubular shell inserted into an arc chamber for creating plasma by a filament, which is disposed in the inner tubular shell and then covered by an end cap. There are at least two outstanding talons disposed on the end surface of the inner tubular shell, and a step gap is configured on between the end surface of the inner tubular shell and the outstanding talons. The end cap can be lodged into the step gap, and fixed. Therefore, the end cap can be easily uncovered from the end of the inner tubular shell, as a result to simplify the replacement of the filament.