Multipactor suppression in high-power cavity-based L-band low-pass filters by edge geometry optimization

Background. Improving the multipactor resilience of high-power microwave devices used in satellite communication systems presents a primary objective for designers of space technology. Aim. This study investigates a method to enhance the multipactor threshold in high-power cavity-based low-pass filters for operation in deep space vacuum with associated radiation factors by optimizing the edge geometry of capacitive sections. Methods. The proposed approach passively suppresses discharge by tailoring the electric field distribution in critical gaps and can be achieved without additive coatings that alter the electrophysical properties of materials, a method commonly employed for this purpose. The research methodology combined electromagnetic field simulation in CST Microwave Studio with thermal analysis in CST MPhysics Studio and resulting field maps using for multipactor stability analysis in SPARK3D, employing an electron tracking algorithm. Results. A key finding is the non-monotonic dependence of the multipactor threshold power on the edge fillet radius. An optimal concave radius of R = 2 mm was identified, increasing the threshold power by approximately 40 % (relative to R = 0,1 mm). Conversely, using a chamfer or a convex rounding degraded performance severely, reducing the threshold power by roughly an order of magnitude. Conclusion. The results are obtained demonstrates the viability of passive geometric techniques as a robust and reliable strategy for multipactor suppression in the design of high-reliability space-borne microwave components.