Characterization of field emitter arrays (FEAs) for a twystrode amplifier

Summary form only given, as follows. The Naval Research Laboratory is currently investigating a new class of microwave power amplifiers based on vacuum microelectronic, field emitter array (FEA) technology. Advantages of using FEAs in microwave amplifiers include instant activation, higher transconductance and higher current densities than thermionic cathodes resulting in higher performance gridded microwave power tubes. A twystrode employing an FEA cathode is being designed to operate at 10 GHz with 50 W output power and 10 dB gain. FEAs will be used to generate an electron beam of up to 40 mA at 2.5 kV with a magnetic field of 5 to 6 kG. Prior to the operation of the FEA cathode in the twystrode, a series of experiments has been undertaken to maximize the beam power and beam transport from the FEA cathode. In these experiments both silicon and metal FEA cathodes are operated under high electric fields of up to 17 kV/cm as required to draw average emission current densities /spl sim/100 A/cm/sup 2/. The beam transport experiment, in which a solenoidal magnetic field will focus the electron beam from the FEA cathode through a conducting cylinder substituted for the twystrode circuit, will be discussed. Recent results from FEA experiments along with the status of the future twystrode experiment will be presented.