High Field Insert Demonstrator Design, Manufacturing, and Tests of the Iseult Whole Body 11.75 T MRI Magnet

A neuroscience research center with very high field magnet resonance imaging (MRI) equipment has been opened in November 2006 in the Neurospin site of French Atomic Energy and Alternative Energies Commission (CEA, Saclay, France). One of the imaging systems, the so-called Iseult project, will require a whole body 11.75 T MRI magnet with a 900-mm warm bore. The coil is made of a niobium-titanium conductor cooled by a He II bath at 1.8 K, permanently connected to a cryoplant. The main coil is made of a stack of 170 double pancakes submitted to a peak field up to 12 T. A demonstrator made of six reduced double pancakes using the conductor developed for this project has been designed, manufactured, and tested at CEA/Saclay. The objective was to demonstrate that the Iseult main coil winding pack is able to sustain the high stress level calculated, 170 MPa azimuthally and 110 MPa radially. This demonstrator has been successfully energized up to 6000 A in a background field. A maximum azimuthal stress of 225 MPa has been reached, much higher than the nominal Iseult value. This paper presents the design, the manufacturing, and the cryogenics test results of this demonstrator.