A sputter-ion-pump system includes a sputter ion pump and an electronic drive. The electronic drive supplies a voltage across the ion pump to establish, in cooperation with a magnetic field, a Penning trap within the ion pump. A current sensor measures the Penning-trap current across the Penning trap. The Penning trap is used as an indication of pressure within the ion pump or a vacuum chamber including or in fluid communication with the ion pump. The pressure information can be used to determine flow rates, e.g., due to a load, outgassing, and/or leakage from an ambient.