Use of distributed cathode in crossed-field amplifiers

Summary form only given. Crossed-Field Amplifiers (CFAs) use thermionic emission or secondary electron emission for their current sources. These sources do not allow spatial or temporal modulation of the current. One limit in the gain of CFAs is the input current. Too much injected electron current can swamp the RF input signal. One way to increase the device gain is by using the emitting-sole design. This design uses secondary electron emission along the sole electrode of the device to provide high current density. This approach is, in effect, a distributed cathode, but there is no control over the electron current along the device. The use of distributed Field Emission Arrays (FEAs) in CFAs has been proposed. FEAs may allow active temporal and spatial control in CFAs. By having control over the distributed sources, it is possible that the gain can be increased. Also, a distributed cathode allows for a method to study the physics of the device in great detail. The way in which noise propagates can be studied by perturbing the emitted current from various locations. A distributed source CFA is studied both experimentally and computationally. The CFA device uses a meander line slow wave circuit and operates somewhere in the 600 to 900 MHz range. Simulations of the slow wave circuit using VORPAL, ICEPIC, and COMSOL will be presented. The wave pattern of the meander slow wave circuit will be mapped spatially, and the traveling wave components of the field will be measured with a high speed oscilloscope. These results will be compared with the simulations. The relationship between the gain and the number of sources, placement of the sources, and timing of the sources will all be studied both experimentally and by simulation.