Analytical calculations and comparison with numerical data for annular klystrode

The performance of a klystrode is investigated for annular electron beams. Numerical simulations of the output cavity in the klystrode device are carried out by making use of the fully electromagnetic three-dimensional code, HFSS, and the fully electromagnetic, two-and-one-half-dimensional, self-consistent PIC code, MAGIC. In addition, an analytical expression to predict the efficiency and gap-field strength of the device is developed to investigate klystrode performance over a wide range of parameters. This analytical expression for the annular klystrode is developed based on the Maxwell's equations and Newton's second law of motion. The analytical results agree fairly well with data obtained numerically from the MAGIC code. The presented results indicate that the theoretical formula obtained from the analytical calculation may be useful for designing the klystrode microwave tubes.