Computer simulation and experimental study of quench in superconducting epoxy-impregnated multi-layer coil

The quench behaviour of a single superconducting epoxy-impregnated coil is analyzed in full by means of a computer code developed, in comparison with detailed experiment in which time-dependent temperature of composite wire (cable) at different points of the winding, current decay, electrical voltages across turns, normal zone front velocities in all directions are measured. The 3D transient heat conduction equation with a source term reduces to the set of 1D transient non-linear differential-integral-difference heat balance equations governing dynamically interdependent processes of heat propagation along helix-shaped wire within the winding layers and of heat transfer (in radial and axial directions) through inter-turn insulation of finite thickness. The heat balance equations coupled with the circuit equation for the transport current are solved numerically by the finite difference method. The effect of the helical-discrete structure of the winding formed by helix-shaped metallic wire, the turns and layers of which are separated by weakly conducting insulating material, on the winding temperature profile and the normal zone front velocity is demonstrated.