Provided herein are approaches for controlling particle trajectory from a beam-line electrostatic element. In an exemplary approach, a beam-line electrostatic element is disposed along a beam-line of an electrostatic filter (EF), and a voltage is supplied to the beam-line electrostatic element to generate an electrostatic field surrounding the beam-line electrostatic element, agitating a layer of contamination particles formed on the beam-line electrostatic element. A trajectory of a set of particles from the layer of contamination particles is then modified to direct the set of particles to a desired location within the EF. In one approach, the trajectory is controlled by providing an additional electrode adjacent the beam-line electrostatic element, and supplying a voltage to the additional electrode to control a local electrostatic field in proximity to the beam-line electrostatic element. In another approach, the trajectory is influenced by one or more geometric features of the beam-line electrostatic element.