Fabrication of non-magnetic multi-pin coaxial vacuum feedthrough system for cryogenic applications

We have developed and tested a compact non-magnetic feedthrough made of epoxy resin and capable of maintaining vacuum leak tightness over a wide temperature range (300 K-4 K). It is equipped with 15 electrical pins and three 50 Ω coaxial lines. The feedthrough has been designed to apply a high voltage (up to 5 kV) and transmit radio-frequency signals for operating a Penning trap over a wide temperature range (300 K-4 K). The characteristic impedances of the coaxial lines have been measured at 300 K and 77 K and found to remain ∼50 Ω over the frequency range of our interest (10 MHz-80 MHz). The details of its fabrication and performance over a wide temperature range have been discussed.