Rotor Modeling at Low Temperature for NMR

N. Luchier [1,2], P. Forestier [1,2], E. Bouleau [1,2]
[1] Univ. Grenoble Alpes, Grenoble, France
[2] CEA, Grenoble, France
Published in 2015

Our laboratory is currently leading the design and the manufacture of a novel device that allows NMR spectroscopy to be cooled down to cryogenics temperature (in the 10-100 K range). The system features a sample-holder that rotates at very high frequencies (f >10 kHz). Two aerostatics gas-bearings, allows this sample holder to be suspended in its chamber thanks to a Helium flow. A second Helium flux on a rotor allows for the rotation. Due to high variation of Helium gas properties, the control process is complex.

We present the modeling of the sample-holder down to 10 K. Both the gas-bearings and the rotation are modeling as different temperatures as a function of time. The model mixes CFD, thermal and mechanical COMSOL nodes. We present the model in details as well as its results.