Mechanical and helium cooling factors in dipole magnet training

An investigation of the roles of prestress, friction and cooling in the alleviation of the problem of training in superconducting dipole magnets is undertaken. An analysis of the Lorentz force and its influence on variously pre-stressed coils is presented. Mechanical tests have been made on typical coil materials. Material characteristics are used in the calculation of the coil pre-stress level attained in several magnets. The training behavior of these magnets is shown to depend on the coil pre-stress level attained, although the prediction is more pessimistic than the actual performance. Finally, the strongly beneficial influence of enhanced heat removal in superfuid helium-II is demonstrated.