According to the invention, in order to suppress a latch-up, the supply voltage is switched off following the detection of a latch-up, charge located in the circuit is reduced with the air of a short-circuiting switch, and the detection of a low voltage is temporarily canceled when the supply voltage is gradually increased again. In certain example embodiments, a magnet yoke assembly used in the ion source is provided, and the magnet yoke assembly includes a lower yoke and an upper yoke. The deconvolution processing may implement a Weiner filter that uses data corresponding to a near-field point spread function of the lens unit.