X-ray tube with magnetic electron steering

#This invention relates to the field of X-ray tubes, specifically tubes wherein a magnetic field urges electrons toward the anode.

#X-ray sources have many applications. For example, hundred kilovolt X-ray tubes can be used in agriculture for de-infestation of fruits, vegetables, grains, and lumber. They can also be used to sterilize food for storage without refrigeration, and to destroy pathogenic microorganisms in meat, seafood, and poultry. They can also be used for non-destructive testing and inspection of industrial tools and systems (e.g., airplanes) and for water purification.

#Many X-ray tubes consist of an electron source and an accelerating potential that impinges a beam of electrons onto an X-ray conversion target anode. The anode is typically made of a high atomic number material so that it efficiently decelerates the electrons that penetrate into it, thus generating Bremsstrahlung X-radiation. Many production processing applications require electron beams of only a few hundred kilovolts accelerating potential, so the X-ray pattern is substantially isotropic.

#The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

#FIG. 1 is a schematic view of a conventional X-ray tube.

#FIG. 2 is a schematic view of an X-ray tube according to the present invention.

#The present invention provides an X-ray tube that uses magnetic steering of electrons to increase the tube's X-ray production efficiency and reduce cooling required to cool the X-ray tube.

#FIG. 2 shows a schematic view of an X-ray tube T2 according to the present invention. Envelope E2 defines an evacuated interior volume V2. Cathode C2 mounts with envelope E2 so that at least a portion of cathode C2 is in communication with interior volume V2. Anode A2 mounts with envelope E2 so that at least a portion of anode A2 is in communication with interior volume V2. Magnetic field generator M2 mounts with envelope E2. Grid G2 mounts with envelope E2 and can modulates the quantity and initial trajectories of electrons from cathode C2.

#A narrow cathode C2 and grid G2 structure such as shown in FIG. 2 can minimize shadowing of generated X-rays. The electric field lines from a narrow cathode C2 and grid G2 structure are divergent, however, making it more likely that electrons from cathode C2 and grid G2 structure will not hit the anode A2 and generate X-rays, but rather strike other structures and generate only heat. Thus, when using a narrow cathode C2 and grid G2 structure it can be important to provide a means of containing and guiding the electrons from narrow cathode C2 and grid G2 structure onto the anode A2.