Bright and Durable Pulsed Field-Emission Source

Remarkable advances in the emerging field of Ultrafast Electron Microscopy (UEM) now permit high spatialresolution imaging of dynamic processes with temporal resolution in the femtosecond range. However, limitations with pulsed electron sources in brightness have prevented this technique from achieving its full potential. A brighter ultrafast electron-gun using improved field emission technology would enhance UEM capabilities at leading research facilities, including those funded by the Department of Energy. How this Problem is being addressed Deficiencies associated with conventional field emitters used in pulsed electron sources are being addressed with the development of innovative advances to their design and fabrication methods. These field emitters are projected to exhibit superior operational performance, and also extreme reliability due to their unique capacity of being regenerated to original condition in-situ after undergoing operational degradation from laser and ion impact damage. What was done in Phase I During Phase I research, a high-vacuum test chamber for studying the production of field emission structures using our proprietary methods was designed and constructed. The technical feasibility of the process was completely validated. The characteristics of these field emitters were studied, and an initial test of laser-assisted field emission was demonstrated. Practical means to incorporate this technology into electron guns were devised. A key partnership for Phase II R&D and Phase III commercialization was formed. What is to be done in Phase II A complete electron gun system incorporating this new technology will be assembled. This apparatus will be run in the laser-assisted field emission mode in both nanosecond and picosecond temporal ranges. Some initial experiments will be performed, and the technology will be readied for commercialization. Other potential applications for this field emission technology will also be studied. Commercial Applications and Other Benefits In addition to its application in UEM, the technology being developed here should find productive use in more conventional forms of electron microscopy. Other scientific instrumentation that requires very bright particle-beam sources will also benefit from the superior emission characteristics and durability of this novel field emission technology. This will increase the commercial potential of this project well beyond the specialized field of UEM. Although this proposal is responsive to DOE needs in electron microscopy, this research may also prove valuable for other departmental interests such as high-energy electron accelerators and free electron lasers.