High temperature braze flow control during manufacturing of dispenser cathodes

The study has been performed to explore undesired flow of a Mo-Ni braze filler metal over Mo-Re heat shields substrate during manufacturing of dispenser cathodes. The ultimate goal was to develop an optimal design to help control the flow of the braze material and still satisfy other requirements, such as a uniform heat transfer, structural stability, functionality, as well as requirements with respect to quality, reliability, and durability. This paper presents brief results of the series of tests featuring uncontrollable filler metal spreading during brazing. Several related issues have been studied and results will be addressed. Improved designs will be proposed and compared with existing ones using a qualitative evaluation of a design of a brazed structure recently proposed.