Electrical and Thermal Design of ka-band Dual- Anode Electron Gun with PPM Focusing for Space Applications

Space Traveling Wave Tubes (TWTs) have special constraints pertaining to compact size, less weight, and high-efficiency requirements. In order to achieve these design objectives, each and every component of the space TWT has to be designed taking into account these space requirements. In this work, the authors have designed a dual-anode electron gun for ka-band space TWT, which offers the flexibility to change the beam current through telemetry command remotely during its operation to compensate for unintended performance degradation. The capability for tuning the beam current is offered by changing the control anode voltage, which is studied in detail in this paper. After optimizing the electron gun design for desired beam parameters, the design of a periodic permanent magnet (PPM) structure has also been carried out. The optimization of the PPM structural parameters and magnetic field values to attain a confined flow of electron beam with less scalloping percentage has been carried out. The thermal analysis of the dual-anode electron gun has also been performed to study the temperature distribution and thermal displacements within the electron gun to ensure the safety limits.