Field inhomogeneity effect on the quench current of LHC dipole magnets

The calculation of the maximum field of superconducting magnets is carried out by comparing the cable critical current line (Ic vs B) with the magnet load line. In order to take into account the self field effects in critical current measurements, both the lines commonly refer to the maximum magnetic field at the conductor. In case of dipole magnets for high energy physics applications, in which the cable experiences a strong field inhomogeneity, another criterion (the effective field one) can be adopted, considering the field distribution inside the cable. Furthermore the transition smoothness and the thermal exchange can be considered. The paper describes the results of the calculation obtained for LHC dipoles: the maximum current value comes out to be little higher (about 3%) if the new criteria are adopted instead of the maximum field criterion