Reusable ultrahigh vacuum viewport bakeable to 240 °C

Abstract

We have developed a removable and bakeable viewport for UHV applications. The viewport consists of a modified blank Conflat flange; a ring of flux-free solder to form a vacuum seal; a viewport window; a clamping flange, and conical disk springs. We have cyclically baked viewports up to 240 °C and have achieved an ultimate pressure of 1.2×10−10 Torr (limited by our pumping station), with no leak detected at the 10−10 atm cm3/s level. Both BK7 and zinc selenide windows have been used successfully.