Electrophoretically applied dielectrics for amorphous metal foils used in pulsed power saturable reactors

Amorphous metal foil-wound inductors have been tested as ferromagnetic saturable inductive elements for pulse-power (multi-terawatt) switching nodules. Saturation switching may provide large 100 ns current bursts necessary to accelerate ion beams for the fusion fuel pellet implosion required, for example, in PBFA (particle beam fusion accelerator) operation. In simulated capacitor testing premature dielectric breakdown of thin polyethylene terephthalate film insulation in the inductor windings occurs at considerably below 2500 V. This appears to be due to inadvertent dielectric damage from micro-spikes on the amorphous foil surface. Electron micrographs and dielectric breakdown data illustrate that electrophoretically-applied dielectric coatings, deposited from organic aqueous colloid dispersions, can be used to provide insulating coatings on the foil which provide a 240% improvement (6000 V) in the breakdown strength of wound amorphous foil inductors. The theory and operation of a dedicated electrophoretic continuous coating system is described