One-sided Permanent Magnets for mobile MRI

There are many cases where the sample, object or subject we want to study cannot be brought at the laboratory and be placed inside the bore of a high field super-conducting magnet. Such situations appear often in industrial and biomedical applications. Additionally in many case access is limited to one half of the space (for example when trying to measure moisture inside a wall), and a one-sided detection system is needed. This direction of research was initiated with the project named NMR2GO funded by the ANR (contract ANR-06-JCJC-0061) and has now reached the point were uniform one-sided magnets are built and are operational. The goal of the project is to design and built uniform permanent magnets with MRI characteristics. One such magnet is shown on the figure on the right. It generates a uniform gradient above its surface, which remains linear for many cm inside the object under study. Applications of this device in surface sciences are curently underway.

Permanent Magnets for Spectroscopy

Following the previous direction of research we have developped a theory that is capable of describing bothe one-sided as well as closed magnets. In the latter case the homogeneity can be achieved easier at a higher magnetic field can be produced. In these conditions spectroscopic information can be retrieved. This objective was initiated with the project named R-EVOLUTION-M-R (for Rotating Evolution Magnetic Resonance) funded by the ERC (2007-Starting Grant 205119) and has now reached the point were uniform cylindrical magnets are built. One such magnet is shown on the figure on the left. It generates a uniform magnetic field in its center over many mm3. The goal of the project is to design and built uniform cylindrical permanent magnets with NMR characteristics, capable of performing high resolution localized spectroscopy. This 5 year project is currently underway.

Superconducting Field Stability in Driven Mode

Field stability for permanent magnets is a non trivial problem. A similar problem exists in the case of superconducting magnets when operating in a driven mode. We have contributed in a collaboration with the Institute of Research into the Fundamental Laws of the Universe towards the evaluation of the field stability of very high field MRI magnets that are currently studied for the Neurospin project. We have been using the microcoil detectors to access this information in the presence of field drifts both in high and very low temperatures.