A system includes an ion source configured to generate ions having a first polarity, one or more extraction electrodes configured to extract the ions from the ion source as an ion beam having an extraction energy, a mass resolving slit or aperture configured to select a desired isotope from the ion beam such that a desired isotopic ion beam passes through the mass resolving slit or aperture, a target positioned relative to the mass resolving slit or aperture so that the desired isotopic ion beam is incident on the target, and a voltage source coupled to the target and configured to hold the target at a first voltage having the first polarity. The first voltage causes a reduction of the extraction energy as the desired isotopic ion beam approaches the target to minimize sputtering and maximize collection of the ions on the target to reconstitute an ionized material.