Computer simulation of cross field amplifiers

Summary form only given. The author has developed a simulation model of cross field amplifiers (CFAs) using the PIC (particle-in-cell) code CONDOR. The main advance of this model over previous CFA simulations is the realistic tracking of absorption and secondary emission. The code uses experimental curves to calculate secondary production as a function of absorbed energy and angle. This code was to model the 100-MW X-band CFA under construction at SLAC (Stanford Linear Accelerator Center). Several questions of practical interest have been examined. e.g., maximum RF field limitations (from hub depletion and anode heating). the power and spectrum of absorbed electrons, the minimum traveling-wave field needed to initiate spoke formation, and the variation of output power with DC voltage, anode-cathode gap, and magnetic field. For a backward-wave device like the SLAC CFA, modeling only the synchronous harmonic was not adequate to calculate the cathode bombardment. This is because the fundamental has a longer wavelength than the synchronous harmonic and is stronger at the cathode. By looking at particular phase shifts for which the first two harmonics have a small common denominator, the author has modeled the effects of both the fundamental and the synchronous waves