An apparatus for Flash X-ray irradiation of material includes a Flash X-raysourcecomprised of an electron gun and an anode. The electron gun comprises a fieldemission coldcathode having an electron emitting surface, and a grid for controllingelectron flow from thecathode to the anode. The anode has an electron-receiving main surface and anX-ray emitting,oppositely facing main surface. The X-ray emitting surface emits X-radiationinto an irradiationvolume. The X-ray emitting surface of the anode has orthogonally orientedfirst and seconddimensions of greater than 2 millimeters each. A high voltage pulse powersupply powers theFlash X-ray source. The electron gun, anode and high voltage pulse powersupply are soconstructed as to create sufficient X-radiation in said irradiation volume toachieve a desiredlevel of irradiation of material in said volume.
