Optical Cavity Enhanced Electron Emitters

Electron emission cathodes are used in a wide variety of applications, including but not limited to, electron microscopes, electron beam lithography, space propulsion, high power microwave (HPM) devices, free electron lasers, and displays. HPM sources for millimeter-wave and terahertz radiation are of great interest for military and defense applications such as radar, electronic counter measures, and communications. Electron emission cathodes are central to HPMs, and thus improvements in cathodes, such as increases in current emission capability, reduction in power, improvements in lifetime, and reduction of size/complexity directly affect the power and frequency response for a range of military and civilian applications. Traditionally, thermionic cathodes are utilized in HPMs. However, these typically require very high applied voltages, up to 500 kV to generate electron pulses and require proper thermal management to handle the high temperatures at the emitter.