A processing chamber having an improved sealing means is disclosed. The processing chamber comprises a lower element, an upper element, and a seal energizer. The seal energizer is configured to maintain the upper element against the lower element to maintain a processing volume. The seal energizer is further configured to generate a sealing pressure in a seal-energizing cavity that varies non-linearly with a processing pressure generated within the processing volume. In one embodiment, the seal energizer is configured to minimize a non-negative net force against one of the upper element and the lower element above a threshold value. The net force follows the equation P2*A2-P1*A1, where P2 equals the sealing pressure, P1 equals the processing pressure, A2 equals a cross-sectional area of the seal-energizing cavity, and A1 equals a cross-sectional area of the processing volume.