An apparatus includes a conductive structure and an insulated conductor disposed proximate an exterior portion of the conductive structure to modify an electric field about the conductive structure. The insulated conductor has an insulator with a dielectric strength greater than 75 kilovolts (kV)/inch...http://www.google.de/patents/US7675046?utm_source=gb-gplus-sharePatent US7675046 - Terminal structure of an ion implanter
