High Current Diamond Microtip Cathode

155 High Current Diamond Microtip Cathode--Systems & Processes Engineering Corporation (SPEC), 401 Camp Craft Road, Austin, TX 78746-6558; (512) 306-1100 Dr. Keith D. Jamison, Principal Investigator Ms. Diane Joyce, Business Official DOE Grant No. DE-FG03-97ER82493 Amount: $75,000 There exists a continuing need for high current, field emission electron sources (i.e., cold cathodes) for use in high power vacuum electronic devices such as klystrons, gyrotrons, and high-brightness electron sources used in particle accelerators and other electronic sources. Current low-temperature cathode technology cannot reliably deliver the desired high current density for these applications. A robust, high current density, long-life field emission cathode is being developed that is capable of producing current densities greater than standard thermionic cathodes. This gated cathode is based on field emission from diamond microtip arrays. The diamond microtip cathode is insensitive to contamination, turns on at low electric fields, has stable emission, and can operate at specific power densities that are higher than typical molybdenum or silicon microtip cathodes. In Phase I of this project, a gated diamond microtip array will be constructed and tested to demonstrate longevity, emission uniformity, contamination insensitivity, and the ability of these devices to produce pulsed current densities greater than 10 amperes per square centimeter. Shaping of the gated microtip array will also be explored to determine whether the diamond microtip cold cathode can emulate the curved cathode geometry used in many high power klystron applications. In Phase II prototype cathodes optimized for use as high brightness electron sources for klystrons, gyrotrons and accelerators will be produced and tested. Commercial Applications and Other Benefits as described by the awardee: There are many commercial applications for robust, high brightness cold cathodes. Their most obvious use is in vacuum microelectronic devices such as amplifiers. Additionally the field emission electron source developed in this project will have significant applications in other areas such as alternate electron sources for televisions, vacuum gauge tubes, and as starters for fluorescent lights.