The present invention relates to an x-ray source, comprising a field emission cathode, an anode, connectors for allowing application of a high voltage between the cathode and the anode for enabling emission of an x-ray beam, and an evacuated chamber inside of which the anode and the cathode are arranged, the evacuated chamber having an x-ray transparent window, wherein the field emission cathode consists of a carbonized solid compound foam having a continuous cellular structure, the continuous cellular structure providing multiple emission cites for emission of electrons onto the anode when the high voltage is applied. The field emission cathode provides for the possibility to increase the efficiency of the x-ray system as it is possible to in a much higher degree control the electrons emitted by the field emission cathode in terms of switching time, current, kinetic energy and the emission direction. EP2221848A1
