Abstract: An X-ray tube having a capability to produce multiple anode spots. The X-ray tube can produce three or more different size anode focal spots without modification of the connectors, cabling, or high voltage supply for routing high voltage signals to the X-ray tube. An isolating fiber optic control input connects an external light emitting diode to a controller inside the tube housing. The controller responds to light signals from the light emitting diode to control the size of focus spots on the tube anode. In a preferred embodiment each of three filaments are individually energized to produce three different size focal spots and a cathode cup to which the filaments are mounted is also biased to add a four spot capability. In an alternate embodiment a split or segmented cathode cup has its segments biased to different electrical potentials by tapping power from a conventional high voltage filament supply used in energizing a cathode filament.

Abstract: Method and apparatus is disclosed for providing a beam of X-radiation having an intensity value which is rapidly switchable between nonzero levels. An X-ray tube having one or more electron-emitting thermionic filaments is provided with cathode bias control circuitry for limiting electron flow between the tube's cathode and anode structures. The bias control circuitry applies one of a plurality of predetermined values of negative potential to a cathode cup structure for allowing predetermined quanta of electrons emitted from an energized filament to reach the anode.One value of the negative potential bias is a relatively large value for cutting off all flow of electrons; a second or intermediate value of negative voltage bias allows a predetermined fraction of the total quanta of emitted electrons to flow; and a third potential value allows a greater number of electrons to flow.

Abstract: An X-ray tube includes a rotor body having an outer sleeve of copper and an inner sleeve of steel, the two sleeves being joined by brazing. A black coating is applied to the outer surface of the copper sleeve and the inner surface of the steel sleeve, as well as to the outer surface of a copper bearing housing concentrically disposed within the rotor body. A steel spindle is concentrically and rotatably supported within the housing by a bearing structure and is rigidly affixed to the rotor body to support the rotor body for rotation. The X-ray tube also includes an anode comprised of molybdenum having a coating of rhenium-tungsten. The anode is supported on a shaft comprised of a material having a low coefficient of thermal conductivity such as niobium, an alloy of niobium, molybdenum, or an alloy of molybdenum. The X-ray tube further includes a bearing structure having portions lubricated by lead.

Abstract: A dual filament, rotary anode X-ray tube generates X-radiation of extraordinary uniform cross-sectional intensity by focusing a pair of electron flows on a target to produce partially overlapping focal spots. A pair of electron-emitting filaments are independently and adjustably excited for producing the flows of the electrons, each of which produces a line focus-type focal spot. The filaments are positioned in respective focusing cups which are configured and electrically biased to provide a degree of focal-spot overlap which produces a uniform distribution of electrons on the combined focal spots. The uniform electron distribution on the combined focal spots produces a uniform distribution of emitted X-radiation.In another embodiment the electrons from the respective filaments are focused to provide radially aligned and adjacent inner and outer focal spots on the target. The flow of electrons to the outer focal spot is more heavily concentrated than the flow to the inward focal spot.