Low emission, high current density field emission cold cathode

Working at the Air Force Research Laboratory’s Directed Energy Director-ate, Dr. Donald Shiffler discovered an important, innovative way to make cold cathodes that are far more efficient and easier to manufacture than cold cath-odes utilizing previous technologies. To make these advanced devices, a carbon substrate is covered with com-mercially available, high-aspect ratio carbon fibers that are coated with cesi-ated salts using a proprietary treatment process. This cold cathode technology can de-liver high electron current densities using very low power, thereby allowing the systems in which they’re installed to operate at cool tem-peratures and be light in weight. The new cold cathodes solve a nagging, “show-stopping” problem for the Air Force, which had been stymied by the lack of an emitter that could be used to proper effect in a high-pow-ered microwave tube. While this cold cathode innovation has been de-veloped primarily for use in military high power microwave devices, the transfer partners also envision broader uses in the fields of public and private security, health care, and materials characterization. Further possible applications include enhanced x-ray screening systems, which could be developed for use by homeland security as well as private security firms. Sub-stantial improvements in resolution for material characterization are also feasible. Incorpora-tion of the invention into x-ray technology could lead to better and safer radiation treatment for cancer patients, as well as more detailed and accurate mammograms.The cesiated salt-coated carbon fiber, carbon substrate, cold cathode technology has been transferred to Fiore Industries of Albuquerque, New Mexico, through a licensing agreement. The technology has been further transferred to the private sector through CRADAs with com-panies that are developing x-ray tubes based on this cold cathode technology. Dr. Shiffler’s cold cathode technology has also been directly transferred through consultation and discussion to other federal labs, including DOE’s Sandia National Laboratories.
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