Advanced Dispenser Cathodes
Controlled porosity reservoir cathodes offer significantly improved performance over conventional impregnated cathodes. Optimized performance requires additional design to achieve reduced barium deposition on adjacent surfaces, increased lifetime, and high current density emission. This paper describes the achievable performance and the associated design requirements.
Design and 3-D Simulations of a 10-kW/28-GHz Gyrotron With a Segmented Emitter Based on Controlled Porosity-Reservoir Cathodes
In this paper, the design of a 10-kW/28-GHz gyrotron is presented. The main characteristic of the new gyrotron is the emitter ring, which is assembled from twelve individually supplied emitters based on controlled-porosity reservoir (CPR) technology. The main goal is to evaluate the use of CPR emitters for gyrotron applications. In addition, the azimuthally segmented emitter ring could be used for the generation of controlled nonuniform electron beams. In this way, it is planned to experimentally study the effect of nonuniform emission on the gyrotron operation. In this context, the effect of nonuniform emission on the beam quality is numerically investigated using the 3-D, electrostatic, parallel-code Ariadne, while the effect of the degraded beam on mode coupling and stability of the wave-particle interaction in the cavity is numerically studied using the nonstationary, self-consistent multimode cavity code Euridice.
Scandate cathode fundamentals: interactions of Ba, O and Sc on W
Current developmental efforts on scandate cathodes are concentrated on improving uniformity in the emission and robustness in the performance. These endeavors require a good understanding of fundamental issues such as the emission mechanism and the Sc-replenishment mechanism associated with the cathodes. In order to help achieve this understanding, it is essential to unravel the complex chemical interactions on the scandate cathode surface, on which Ba, O, Sc and W are present. Our approach to investigate the complex interactions is to study first the interactions within the subsets, such as Ba and O on W and Sc and O on W. Aided with the knowledge gained, we then study the complete set of interactions.