An efficient multipaction suppression method in microwave components for space application

Multipaction, caused by the secondary electron emission phenomenon, has been a challenge in space applications due to the resulting degradation of system performance as well as the reduction in the service life of high power components. In this paper we report a novel approach to realize an effective increase in the multipaction threshold by employing micro-porous surfaces. Two micro-porous structures, i.e., a regular micro-porous array fabricated by photolithography pattern processing and an irregular micro-porous array fabricated by a direct chemical etching technique, are proposed for suppressing the secondary electron yield (SEY) and multipaction in components, and the benefits are validated both theoretically and experimentally. These surface processing technologies are compatible with the metal plating process, and offer substantial flexibility and accuracy in topology design. The suppression effect is quantified for the first time through the proper fitting of the surface morphology and the corresponding secondary emission properties. Insertion losses when using these structures decrease dramatically compared with regular millimeter-scale structures on high power dielectric windows. SEY tests on samples show that the maximum yield of Ag-plated samples is reduced from 2.17 to 1.58 for directly chemical etched samples. Multipaction testing of actual C-band impedance transformers shows that the discharge thresholds of the processed components increase from 2100 W to 5500 W for photolithography pattern processing and 7200 W for direct chemical etching, respectively. Insertion losses increase from 0.13 dB to only 0.15 dB for both surface treatments in the transmission band. The experimental results agree well with the simulation results, which offers great potential in the quantitative anti-multipaction design of high power microwave components for space applications.