Abstract: An apparatus and method for measuring plasma uniformity and RF uniformity within a plasma chamber. A measurement device is provided within the plasma chamber, where the measurement device includes an electrically conductive surrogate wafer (10) including a planar end wall (12) that is exposed to plasma within the plasma chamber and a printed circuit substrate (20) positioned within the surrogate wafer. The end wall has an aperture (18), and the printed circuit substrate has an ion current collector (26) aligned with the aperture in the end wall. The ion current collector preferably extends within the aperture in the end wall, and the ion current collector has an exposed planar surface that is coplanar with an outer surf of the planar end wall. The device measures ion current flux using the ion current collector, and transmits data from the ion current collector to a receiver located outside of the plasma chamber.