Contractible thermosyphon for conduction cooled superconducting magnets

A thermosyphon, as a thermal switch of a conduction cooled superconducting magnet, was designed, fabricated and tested. When the temperature decreases below the triple point temperature, the working fluid inside the thermosyphon freezes and the thermosyphon does not work as a thermal shunt anymore. Although a usual thermosyphon is at OFF-state below the triple point temperature, there may be heat leak through the thermosyphon wall. The contractible thermosyphon, which has a metal bellows as a contraction component, is proposed to completely eliminate such a heat leak through the wall by mechanical detachment of the thermosyphon at low pressure.