A Bird-Cage Coil for MRI Studies of Unsaturated Granular Materials

Magnetic Resonance Imaging (MRI) is a powerful and non-invasive technique that can be used to reveal useful information about different types of materials. During an MRI experiment a magnetic resonance signal is induced (according to Faraday’s law of induction) in a device called “probe”. MRI probes are simply near field antennas designed in a specific way in order to produce a homogeneous magnetic field at a specific frequency in the region of interest. MRI is a strong technique to study unsaturated granular materials. However, it suffers from a significant drawback, that is inherent small signal-to-noise ratio. To overcome this problem the probe used for a specific MRI experiment must be optimised. In this work a bird-cage probe operating at 21.3 MHz, optimised to study unsaturated granular materials under shear stress as well as some experimental results will be presented.