X-ray source and system comprising an x-ray source

An x-ray source configured to provide an omnidirectional transmission of x-ray radiation, the x-ray source comprising:

• an anode;
• a field emission cathode;
• an evacuated chamber transparent to x-ray radiation, the anode and the field emission cathode being arranged inside of the evacuated envelope,
• wherein the evacuated envelope is an extended tube shaped evacuated chamber having an essentially circular symmetry, the field emission cathode is arranged adjacently to an inside surface of the extended tube shaped evacuated chamber, and the anode is centrally arranged inside of the extended tube shaped evacuated chamber,
• the field emission cathode surrounds the anode,
• the field emission cathode comprises a plurality of ZnO nanostructures selected to be at least 1 micrometer,
• the field emission cathode is substantially transparent to X-ray radiation and formed as a transmission cathode, and
• the x-ray source is connected to a controllable high voltage source, electrons during operation of the x-ray source are accelerated from the field emission cathode in a direction towards the anode, and x-ray radiation is omnidirectionally irradiated from the anode towards and through the field emission cathode and out from the x-ray source.