The present invention provides a combined electrostatically suppressed Faraday and energy contamination monitor and related methods for its use. The apparatus of the present invention is capable of selectively measuring two properties of an ion beam, including, for example, a current and a level of energy contamination in a decelerated ion beam. A first aspect of the invention provides an ion beam measurement apparatus comprising an aperture for receiving the ion beam, a negatively biased electrode disposed adjacent to the aperture, a positively biased electrode disposed adjacent to the negatively biased electrode, a selectively biased electrode disposed adjacent to the positively biased electrode, and a collector, wherein the selectively biased electrode may selectively be negatively biased or positively biased.