Cooling for the Armature Windings in a Repetitively Fired Air-Core Compulsator

A thermal model has been developed to analyze theoretically the cooling in the armature windings of a repetitively fired air-core compulsator. The model is used to predict the cooling effectiveness for helium gas flowing through small passages within the windings. The gas temperature, pressure, and velocity distributions along the coolant tube are predicted and the thermal diffusion inside the armature windings is then calculated. The cooling goal is to stabilize the temperature of the hottest spot on the armature at a given level, which is below the degradation temperature of epoxy, after nine shots. Radial heat diffusion in the combination of aluminium wires, epoxy, and tube dominates the heat transfer mechanisms and determines whether the cooling goal can be achieved. Thus the radial dimension is very critical, so it is important to minimize the armature thickness