Close
Our research interests are focused on key听technology听components in the development of milli-Kelvin cryo coolers. At the present time this is heat switches and the听miniaturization听of the cooling technology.
Many cryogenic systems require heat flow to be controlled. Heat switches provide this control, allowing thermal isolation and connection between different system components. An 鈥榠deal鈥� heat switch would provide complete thermal isolation in its 鈥榦pen鈥� state and a strong thermal link in its 鈥榗losed鈥� state. Complete isolation can only be achieved using mechanical heat switches, which are undesirable for use in space due to the potential for failure.
We are investigating the construction and peformance of solid state heat switches utilizing听the magnetoresitive properties听of tungsten.
Research Area:听Magnetoresistivity
Magnetoresistivity is where the electrical resistance (i.e. its resistivity and thus the electron flow) is affected by the application of a magnetic field. 听As electrons carry energy this equates to a modification in the thermal energy transported in the material (i.e the thermal听conductivity). A large change in thermal conductivity (several听orders of magnitude) can be obtained by the application of a magnetic field in the 1 to 2 Tesla region. 听We are investigating the thermal magnetoresistivity of tungsten to act as a solid state heat switch for our ADRs.
- The difference in thermal conductivity for one of our tungsten switches with a magnetic field of 1.8 Tesla "off" and zero magnetic field "on"
- The as grown tungsten crystal rod
- A completed tungsten heat switch with mounting flanges. 听This is cut from the solid rod by electron discharge machining (EDM).
 A Tungsten magnetoresistive heat switch |  Tungsten single crystals |  As grown tungsten rod |