Publication Date:
2016-01-08
Description:
High magnetic fields (〉1 T) are measured by NMR magnetometers with unrivaled precision if the precessing spin sample provides long coherence times. The longest coherence times are found in diluted 3 He samples, which can be hyperpolarized for sufficient signal strength. In order to have minimal influence on the homogeneity and value of the measured magnetic field, the optimal container for the 3 He should be a perfect sphere. A fused silica sphere with an inner diameter of 8 mm and an outer diameter of 12 mm was made from two hemispheres by diffusion bonding leaving only a small hole for cleaning and evacuation. This hole was closed in vacuum by a CO 2 laser and the inner volume was filled with a few mbars of 3 He via wall permeation. NMR-measurements on such a sample had coherence times of 5 min. While the hemispheres were produced with
Print ISSN:
0034-6748
Electronic ISSN:
1089-7623
Topics:
Electrical Engineering, Measurement and Control Technology
,
Physics