Design and research of high-voltage RF coaxial feedthrough

Background High-voltage RF coaxial vacuum feedthrough serves as an indispensable core part realizing power transmission across vacuum and atmospheric environments for particle accelerators and high-power physics experiments, whose working performance directly determines the operational stability and reliability of the whole experimental system.

Purpose To realize 50 Ω characteristic impedance matching and meet strict vacuum sealing plus high-voltage working requirements, this work proposes a feedthrough design based on ceramic-to-metal sealing technology, so as to supply theoretical basis and practical engineering references for structural improvement of relevant high-voltage RF feedthroughs.

Methods Guided by coaxial transmission line theory, alumina ceramic and PTFE are selected as insulating dielectrics; graded step-transition configuration is adopted to guarantee continuous impedance. Mechanical structure is modeled via SolidWorks, and CST Microwave Studio is employed for high-frequency electromagnetic simulation; a physical prototype is processed and assembled for vacuum and radio frequency performance measurement.

Results In 1–3 GHz band, simulated indicators: VSWR＜1.2, insertion loss＜0.02 dB, characteristic impedance stably ranging from 47.5 Ω to 50.5 Ω. Prototype test results: vacuum leakage rate below 1×10⁻¹³ Pa·m³/s, VSWR＜1.5 and insertion loss＜0.65 dB across full 3 GHz frequency range.

Conclusions The designed feedthrough gains outstanding vacuum tightness and favorable high-frequency transmission property, and the presented material selection and structural design strategy can guide the performance optimization of similar high-voltage vacuum RF feedthrough components.