Development of Conduction-Cooled Cryostat for Superconducting Probe Station

A conduction-cooled cryostat has been developed for NbTi superconducting magnet used in a cryogenic probe station. In a cryogenic probe station, a sample stage for transient measurement is located in the bore of a low-temperature superconducting (LTS) magnet and thermally connected to the second-stage cold head of a cryocooler to cool the sample down to the liquid helium temperature. Two separate structures exist in order to maintain isolation between the LTS magnet and sample stage. The system is cooled by a two-stage cryocooler, and the LTS magnet is charged and generates the designed magnetic field. When the magnet is charged and maintains a certain magnetic field, the temperature of sample stage is varied depending on the amount of heating. The thermal linkage between the LTS magnet and second-stage cold head as well as the sample stage and second-stage cold head is investigated in terms of the stability of LTS magnet, magnetic field, and temperature of sample stage. The mechanical module including the thermal link to control the sample stage is integrated into the system and the results of the performance test are reported.