Multi-path cooling of a turbo-generator rotor winding

A turbo-generator includes a rotor body and a rotor winding disposed around the rotor body. The rotor winding including a sub slot, a first axial cooling duct having a first inlet and a first outlet, and a second axial cooling duct disposed adjacent and parallel to the first axial cooling duct for multi-path cooling. The second axial cooling duct has a second inlet and a second outlet. The first inlet is disposed offset from the second inlet and the first outlet is disposed offset from the second outlet.