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Feasibility of industrial production of MgB 2 cables and magnets has been established, thus leading to MRI systems realization. Apart from continuing the development in performances of both cable and magnet, a further important step consists in applying superconductive junctions to windings, to obtain a better field stability. In 2006 a technique to obtain some tens of Ampere in persistent mode operation in a joined MgB 2 cable was found. Since then, short windings were repetitively built to test the progress of the performances of the junctions. Among them, a single junction, five meter long windings with a diameter of 260 millimeter were put in persistent mode (i. e. with total resistance less than 10 14 Ohm) with 300 Ampere circulating at 20 Kelvin, self-field; also windings with two junctions and about one meter long with the same diameter were put in persistent mode with 200 Ampere circulating at 20 Kelvin, self-field.

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The synchrotron SIS300 is a core component of the FAIR facility, which is under development at GSI. The high intensities of proton and heavy ion beams require the synchrotron to be ramped in a few seconds. In particular, the bending dipole magnets have to be pulsed from the injection magnetic field of 1.5 T up to the maximum field of 4.5 T at the rate of 1 T/s. The fast field ramp together with the particular characteristic to be geometrically curved (the sagitta is 114 mm) make these dipoles critical from design and construction point of views. Aside from the thermal ac losses, the mechanical fatigue is one of the main issues of these 7.8-m long magnets having cos-theta shaped coils with a 100-mm bore. Just the large number of magnetic cycles (10 7 ) oriented the mechanical design to the involvement of stiff structures working at a relatively low stress level with respect to the elastic limits. To this aim, the coils are mechanically supported by 3-mm thick laminated stainless steel collars, assembled through keys, and 1-mm thick iron yoke laminations kept together through large stainless steel C-shaped clamps. The mechanical behavior of these challenging dipoles has been studied in detail through several 2 and 3-D finite-element (FE) analyses. In order to assess the soundness of the mechanical analysis, a series of mechanical studies were performed on stacking samples and single poles under compression, comparing FE computations with the results of the mechanical tests. Finally, the collaring of short models was performed and the measured deformations were compared with expectations.Index Terms-Finite-element (FE) mechanical analysis, pulsed dipole, SIS300.