The objective is to develop cathode assemblies for electric engines, using Advanced Manufacturing (e.g. 3D printing). Besides, the objectives include the reduction of part count number, and the increase of performance in terms of lifetime, robustness to mechanical environment, mass, reliability and electrical performance.
Targeted Improvements:Develop a European cathode suitable for mass production with the following improvements:
- reduction of number of parts by at least 50%.
- reduction of manufacturing time by at least 30%
Description:Cathodes used for electric propulsion currently present a level of complexity that significantly impacts the manufacturing flow, making them incompatible with the large production rate required for example for constellations.
Hollow cathode technology is a fundamental element of all electric thrusters currently used on telecommunications satellites. Therefore, their performance (ability to produce electrons with minimal energy input), lifetime, reliability and manufacturing effort are critical and intricately linked. For high power propulsion systems, the performance is less important, simply because the energy losses in the cathode are small in comparison with thruster throughput. However, for smaller thrusters, cathode performance becomes increasingly important.
Cathode manufacturing is currently so complex that it requires highly skilled staff throughout their assembly. With the prospect of large small spacecraft constellations becoming a reality, it is worthwhile to design hollow cathodes that can be manufactured swiftly and efficiently in large batches and, where feasible, take advantage of performance improvements that could be achieved using alternative manufacture techniques.
Hollow cathode technologies are well mastered in Europe, whether using an oxide dispenser or LaB6 emitter. However, little has been done to simplify their design and optimize their manufacturing flow, probably due tothe low level of production. On the other hand, Advanced Manufacturing (e.g. Additive Manufacturing) includes manufacturing processes that allow to increase the design freedom and the performance, while reducing lead time and manufacturing complexity of spacecraftcomponents.
This activity aims at combining both the strengths of the Advanced Manufacturing and the need for a simplified cathodedesign. In particular, the use of refractory metals (W, Ta, Mo and Re) and ceramics (Al2O3 and AlN) is critical in high power electric propulsion thrusters because of their mechanical and electrical properties, especially at the elevated temperatures and harsh environments to which they are exposed for tens of thousands of hours and thousands of extreme thermal cycles. The design, complexity,and in many instances performance and lifetime, of these components and sub-assemblies is, however, restricted by the limitations imposed by the nature of these materials and the use of conventional machining and joining techniques. The application of Advanced Manufacturing techniques to these materials therefore offers the exciting possibility of improvements in system performance whilst simultaneously increasing production rates.
A hollow cathode engineering model shall be designed, manufactured and tested.
Procurement Policy: C(1) = Activity restricted to non-prime contractors (incl. SMEs). For additional information please go to EMITS news "Industrial Policy measures for non-primes, SMEs and RD entities in ESA programmes".