Large Area, Low Voltage X-Ray Source

The calibration of various x-ray diagnostics at the Laboratory for Laser Energetics requires a spatially uniform x-ray source, the flat-fielding of an x-ray streak camera providing an example. Uniformity may be achieved wilh a point source far away or with a large area source nearby. Our source is based on the bombardment of a lcm by lOcm gold anode with a 3-5 keV electron beam of uniform flux. The beam originates as thermionic emission from a long tungsten filament, and is amplified by secondary electron emission in a discrete dynode chain to the rnA level. The spatial non-unifonnjty of the x-ray source was measured to be +/- 5%. The source may also be gated at 100Hz, useful for measuring geometric distortions in x-ray streak cameras. 2