Effect of pretension, support condition, and cool down on mechanical disturbance of superconducting coils

The applied pretension on the conductor and support condition during coil fabrication has a great effect on the stress state of the coil. Otherwise, the thermal contraction properties of mandrels and coils would cause residual thermal stress during cool down. A combined homogeneous cylinder method was used to analyze the mechanical performance of winding process for the condition of no mandrel support. A finite-element model of solenoid was created to calculate the stress of winding process and cool down. The mandrel support conditions of fixed support at ends of former and radial support along the whole inner surface of former were researched. Mechanical behaviors of one coil used for a 9.4-T magnetic resonance imaging magnet during winding process and cool down were studied based on the aforementioned approach.