The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 18, 2016
Filed:
Sep. 26, 2014
Varian Medical Systems, Inc., Palo Alto, CA (US);
Gary F. Virshup, Cupertino, CA (US);
Stephen G. Bandy, Sunnyvale, CA (US);
Michael C. Green, Palo Alto, CA (US);
Clifford K. Nishimoto, San Jose, CA (US);
James R. Boye, Salt Lake City, UT (US);
VARIAN MEDICAL SYSTEMS, INC., Palo Alto, CA (US);
Abstract
Embodiments include an X-ray cathode filament, filament system, process to manufacture the filament and process to use the filament, where the filament includes a planar substrate, such as of tungsten, having a top surface coated with a coating of carburized tungsten (e.g., WC) and thoria (ThO). A first electron beam is emitted from the coating through a thermionic effect at a first temperature, such as when the filament is heated to between 1700 and 1900 degrees Celsius by running an electrical current through the filament. At this temperature, a second electron beam may be caused by (1) a reaction that includes creating thorium (Th) in the coating, and (2) the thorium diffusing to uncoated surfaces of the substrate from which the second electron beam is emitted. The filament may also have slots forming a zipper shape, forming a square switchback shape, or forming a rectangular labyrinth shape to reduce the current required to heat the filament.