Design and simulation of an S-band cloverleaf amplifier using ICEPIC

Summary form only given. Air Force Research Laboratory (AFRL) is designing a cloverleaf S-band MW-class TWT amplifier. Hot test simulations (58 A, 148 kV electron beam) using ICEPIC have produced 1.2 MW output power. As a step toward a design that will be built and fielded for laboratory investigations, a space-charge-limited electron gun and applied magnetic field were designed and integrated into the existing tube design. The design configurations that achieved these features are based on similar tube designs which have similar current and voltage operating requirements and have been fielded for AFRL laboratory work. The gun is designed to produce electron beam currents ranging from 30 to 50 Amps under voltages in the 140kV to 150 kV range. Mechanical tuning of the anode-cathode gap, as used in previous laboratory realizations of similar designs, can vary the gun perveance over a useful operating range. The applied magnetic field design permits the beam radius to be varied by roughly a factor of two. Calculations of the tube which include the gun and applied magnetic field indicate that the integration of these features works well with the cloverleaf and coupler designs. Current calculations are focused on increasing the hot bandwidth of the tube to 10%. Several implementation options will also be discussed.