project title: Vortex Propagation and Configuration in High Speed Rotation
project leader: Prof. Reyer Jochemsen
access given (in days): 123
access used (in days): 92
local host: Prof. Matti Krusius
home institution: Leiden University
country of institution: The Netherlands
starting date (yyyy-mm-dd): 2005-03-18
Rob de Graaf designed and constructed for his M.Sc. thesis at the University of Leiden a magnetically levitated rotating sample container. The plan was to use this device for studying vortices under high speed rotation. The device turned out to be promising, but a second attempt with a number of improvements was needed. For this he started a collaboration in the low temperature laboratory with the aim to demonstrate the operating capabilities of his rotating sample container and to adapt the design to a rotating blade which would be used inside a sample container at a temperature of around 1 millikelvin, to create turbulence in a sample of superfluid 3He-B.
Rob de Graaf built and tested a more developed example of a magnetically supported and driven rotor with superconducting elements. The rotation velocity is measured optically. So far angular velocities of up to 50 Hz have been achieved in liquid helium at 2 K. It is not yet clear how well this design can be transferred to temperatures which are three orders of magnitude lower. Rob de Graaf has also participated in measurements on the onset temperature of turbulence in superfluid 3He-B, in order to acquire more first hand experience about the study of the dynamics of quantized vortices. Two research reports are in preparation on measurements in which he had major responsibility [14,15]. In addition he was involved in the calibration measurements of the thermometer in Ref. [13].