An extraction electrode arm includes first and second ends spaced apart along a longitudinal axis and first and second sides spaced apart along a lateral axis. The arm also includes first and second surfaces apart, extending longitudinally between the first and second ends and laterally between the first and second sides. The arm further includes a base portion extending from the first end toward the second end and extending between the first and second sides, an end portion longitudinally spaced apart from the base portion and extending to the second end, and a diagonal shank portion extending between the base portion and the end portion and extending laterally from a first diagonal surface region on the first side to a second diagonal surface region on the second side. The diagonal shank portion has a shank thickness that extends laterally between the first and second diagonal surface regions.