A system for controlling the temperature of a semiconductor workpiece processing tool and surrounding structure, thereby reducing the deposition rates within an ion implanter. A faraday flag structure comprising a conductive strike plate coupled to a circuit for monitoring ions striking the strike plate to obtain an indication of the and a base supporting the strike plate that includes a thermally conductive material surrounding at least a portion of an outer perimeter of the strike plate. The faraday flag structure base defines a conduit for routing coolant through the thermally conductive material surrounding the strike plate. Positioned below the faraday flag is a thermally controlled cold trap that receives and retains foreign material appearing in ion implanter.