Work In Progress!

Probes for Cryostats

Planar copper coils were wound using a hand drill and used to develop an AC susceptometry setup.
A potentially superconducting sample is sandwiched between these, and the mutual inductance is monitored as a function of temperature

 

At the SpinLab I had access to a 2″ cryostat capable of cooling down to sub 2K, and it was equipped with a 3-axis vector magnet.

With the help of local machinists, I developed a few odd probes compatible with this cryostat as well as with a 1″ PPMS cryostat belonging to a neighbor.

The design principles were fairly straightforward.
Make a CAD render using SolidWorks.
Start with a standard 2″ flange.  Machine a hole in the center and attach an SS tube of appropriate length via a custom built mating piece. Add twisted pairs of high guage copper wires. Seal with Stycast. Make a distribution box. Start coding.

AC Susceptometry

In order to determine the phase transition temperatures of samples, the mutual inductance between two planar coils placed on either side of them is logged as a function of temperature.

Screenshot of Qt-application coded for AC susceptometry measurements via an SR830 Lock-in amplifier

Screenshot of the Qt-application coded for AC susceptometry measurements via an SR830 Lock-in amplifier

Measurements with the AC susceptometry probe were carried out using an SR830 Lockin amplifier.  This was interfaced with a laptop running Ubuntu by using linux-gpib (I prefer open-source tools ).

The application was developed with PyQt4 and uses PyQtGraph for all its plotting needs.

All source code can be found on its GitHub Repository