Magnets for Magnetic Resonance Imaging (MRI) are required to generate a high homogeneity field over the imaging volume which remains stable in time.
In liquid helium filled systems, it is common to operate the main magnet in persistent mode and to provide a passive shim system comprising a tray of steel shims, the configuration of which must be carefully optimized at a single value of magnetic field. Alternatively, independent superconducting shim coils may be provided, with the current settings carefully optimized for a single value of the main magnetic field. Setting the currents involves inserting a demountable current lead and generating additional liquid helium boil-off. Maintaining these magnets involves regular refilling of the liquid helium reservoir with liquid helium which implies a regular supply of liquid cryogens as well as experience with the handling of liquid cryogens.
With a cryo-cooled magnet, there is no consumption of liquid helium, so it is not so critical to reduce the heat lead to which the system is exposed. Our cryogen-free magnets are fitted with permanently installed current leads made from high temperature superconducting material, allowing the heat load to be minimized even during ramping of the main magnetic field. The maintenance of these systems is relatively trivial, inexpensive and requires no cryogenic experience.
We offer cryogen-free MRI magnets at several field strengths and bore sizes. A high stability magnet power supply with 16 bit resolution and a PC-based control system operating under LabVIEW to control magnetic field sweeps and system cool-down to base temperature are also offered to form a complete and integrated system.
- Suitable for animal studies and human wrist and elbow. Compact and user friendly for teaching and other applications.
- The magnet operates dry and no liquid cryogens are required
- Lightweight and portable
- Runs on mains electricity so can be used anywhere
- No cryogen transfers to organise and carry out.
- Automated measurement sequences allowing unattended operation.
- The open Software allows users to define their own sequences
- Low power consumption cryocooler with low maintenance requirements - only the adsorber needs changing every 30,000 hours running time (dependent on the model)