An X-ray source and a corresponding method for generating X-ray radiation are disclosed. The X-ray source includes a chamber comprising an interaction region, and a first electron source operable to emit a first electron beam, including electrons of a first energy, towards the interaction region such that the first electron beam interacts with a target to generate X-ray radiation. The X-ray source further includes a second electron source adapted to be independently operated to emit a second electron beam including electrons of a second energy for ionising particles in the chamber, and an ion collection tool that is adapted to remove the ionised particles from the chamber by means of an electromagnetic field. By ionising particles and preventing them from moving freely in the chamber, problems related to contamination of the chamber may be mitigated.