A low-loss, ultrahigh vacuum compatible helium cryostat without liquid nitrogen shield

An ultrahigh vacuum compatible compact helium cryostat with a 48 h hold time for a 2.5 l of liquid helium capacity has been realized. The design exploits the large enthalpy of the gas phase helium, by using two layers of vapor-cooled radiation shield in place of the conventional liquid nitrogen jacket. The mechanical rigidity, the absence of liquid nitrogen bubbling, and a low helium boil-off rate make this cryostat particularly suitable for applications that require a low vibration environment such as scanning probe microscopy. (C) 2001 American Institute of Physics.