The current disclosure is directed to a repellent electrode used in a source arc chamber of an ion implanter. The repellent electrode includes a shaft and a repellent body having a repellent surface. The repellent surface has a surface shape that substantially fits the shape of the inner chamber space of the source arc chamber where the repellent body is positioned. A gap between the edge of the repellent body and the inner sidewall of the source arc chamber is minimized to a threshold level that is maintained to avoid a short between the conductive repellent body and the conductive inner sidewall of the source arc chamber.