An Oldham-style coupling assembly wherein a driving shaft is rotatably coupled to a driven shaft using a reduced-lash flexible coupling assembly. In certain embodiments of this invention, both the anode and cathode of the ion source are negatively biased during at least part of a cleaning mode. The disclosed embodiments may further enable individuals to build new virtual worlds within a framework, and allow third party users to better interact with those worlds. A center of the supply aperture is positioned within the acceleration part A. This is achieved by using multiple wells within wells, and coupling the wells to specific voltage potentials to protect the circuit from failure.