Sub-nanosecond Electron Emission from Electrically Gated Field Emitting Arrays

Field Emitting Arrays (FEAs) are a promising alternative to the conventional cathodes in different vacuum electronic devices such as traveling wave tubes, electron accelerators and etc. Electrical gating and modulation capabilities, together with the ability to produce stable and homogeneous electron beam in high electric field environment are the key requirements for their practical application. Due to relatively high gate capacitance, fast controlling of FEA emission is difficult. In order to achieve sub-nanosecond, electrically controlled, FEA based electron emission a special pulsed gate driver was developed. Bipolar high voltage (HV)pulses are used to rapidly inject and remove charge form FEA gate electrode controlling quickly electron extraction gate voltage. Short electron emission pulses (<600 ps FWHM) were observed in low and high gradient (up to 12 MV/m) environment. First attempts were made to combine FEA based electron emission with radio frequency acceleration structures (1.5 GHz) using pulsed preacceleration. The gate driver design together with low inductance FEA chip contact system is described. The results obtained in low and high gradient experimental setups are presented and discussed.