An ultrahigh-vacuum nitrogen-free helium cryostat with small heat losses

The design of a compact ultrahigh-vacuum nitrogen-free helium cryostat is described. The volume of the helium vessel of the cryostat is 2.7 l, and the time of operation after filling it with liquid helium is >65 h. The cryostat satisfies the requirements imposed on ultrahigh-vacuum systems, allows heating to 200°C, and ensures operation at an evacuation level of 10−10 Torr.