Design of an energy recovery system for a Gyrotron backward wave oscillator

To realize the full potential of a Gyrotron backward wave oscillator (Gyro-BWO), an energy recovery system was designed using Particle-In-Cell (PIC) simulations and optimized using both a Genetic Algorithm and PIC simulations. Simulations were carried out to optimize a periodic structure for separation of the spent electron beam and the output radiation produced by a gyro-BWO in the 8.0 - 9.5GHz frequency range. The spent electron beam can be collected using a multi-stage depressed collector. The number and electric potentials of the electrodes were optimized to achieve the best overall recovery efficiency for specific parameters of the spent beam. The 3D PIC code MAGIC was used to simulate electrons´ trajectories and a Genetic Algorithm was used to refine the electrode shapes for optimum efficiency.