Retrosirnulation of a space traveling-wave tube 250 W, Ka-band, 4-stages collector

Abstract: The internship is dedicated to the modeling of RF and electrical performances of a 250 W Ka traveling- wave tube, using computation codes developed internally. The objective was to compare simulations and measurements in order to design a 5-stages collector. The modeling of the interaction wave -beam (RF model) is discussed in the first part. Simulations are done with the internal code MVTRAD. In particular, the gain (at saturation and small signal), the output power and the phase shift are simulated and compared to measurements. Then, we model the collector with the internal code COLLECTD. We look at the electron trajectories and velocities in the collector and we compare the current collected on each electrode to the measurement. Discrepancies have been found between simulations and measurements so that the codes have not been found reliable enough for creating a new design. The objective of the internship changed and we focused on understanding the collector simulation discrepancies.