US Patent 7259651 Energy storage coil

An energy storage coil comprises a core having an electrical conductor wound thereabout in a plurality of turns. The turns define a main zone and at least one first auxiliary zone extending along the core. The main zone has a first end and a second end. The turns in the main zone overlie one another. The first auxiliary zone is arranged adjacent to the first end of the main zone. The turns in the first auxiliary zone are arranged to provide the first auxiliary zone with lower parasitic capacitance from turn to turn than the main zone.