CRYOSTAT WITH LIQUID NITROGEN (LN2) BATH

摘要

PURPOSE: To obtain a cryostat including an LN2 bath where gas loss is avoided by providing a container including a cover for accomodation in the LN2 bath, and forming with the cover a supporter for a cooling head. CONSTITUTION: A cryostat 1 includes a container 2 including a cover 3. An LN2 bath (liquid nitrogen bath) is provided in the container 2, and parts to be cooled are put in the LN2 bath. The cover 3 includes a hood having a flange bottom 8, and a cooling head 11 is fixed to the flange bottom and is protruded into the container 2 at a cooling end 12. When pressure in a chamber 28 is lowered from the outside, force of a compression spring 27 lifts the cooling head 11 whereby dipping depth of the cooling head can be controlled depending upon a load of the LN2 bath. For example, when the load of the LN2 bath is increased, pressure in the cryostat is raised, and pressure in the chamber 28 is also increased, and the cooling head 11 is more deeply dipped in the LN2 bath. Upon non-operation of the cooling head 11 the cooling head is lifted upward with supply of the pressure in the chamber 26 whereby heat conduction loss through the cooling head is reduced.