Patent attributes
In accordance with one embodiment of the present invention, there is provided a switch-mode power supply to generate the heating current for a hot-filament electron-emitting cathode. The power supply directly couples, without an output power transformer, the output from a full-bridge converter that operates at an output frequency in the range from ten Hz to tens of Khz to the output terminals of the power supply. A connection to a reference potential that minimizes the potential fluctuation of the cathode is provided by the center tap on an autotransformer connected across the output terminals, where the conductors in the autotransformer are sized for half of the emission current from the cathode rather than the much larger heating current.
