title: Note: Cryogenic heat switch with stepper motor actuator.
abstract: A mechanical cryogenic heat switch has been developed using a commercially available stepper motor and control electronics. The motor requires 4 leads, each carrying a maximum, pulsed current of 0.5 A. With slight modifications of the stepper motor, the switch functions reliably in vacuum at temperatures between 300 K and 4 K. The switch generates a clamping force of 262 N at room temperature. At 4 K it achieves an "on state" thermal conductance of 5.04 mW/K and no conductance in the "off state." The switch is optimized for cycling an adiabatic demagnetization refrigerator.
authors.affiliation: Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: B S
authors.initials: BS
authors.lastname: Melcher
authors.affiliation: Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: P T
authors.initials: PT
authors.lastname: Timbie