The x-ray source (2) that the present invention relates to a kind of for imaging device comprising: at least three electrodes Power supply, it is configured as providing primary clearance voltage between the first electrode (13) among at least three electrode and second electrode (12), the primary clearance voltage has AC components, causes the transmission from the first electrode towards the electronics of the second electrode And controller, it is configured as supplying variable potential on the third electrode (14) among at least three electrode, wherein, the x-ray source is configured as generating the X-ray beam with power spectrum based on the voltage difference between the first electrode and the second electrode, and wherein, the controller is configured as setting the variable potential on the third electrode to cause the value of the transmission of the electronics at least partly stopped per when a predetermined condition is satisfied.
