A gas sensor includes a first chamber containing a plurality of evenly spaced rods having voltages applied thereto to cause gas ions in the first chamber to move in a direction from a first end of the first chamber to a second end of the first chamber and a second chamber coupled to the second end of the first chamber and having at least one ion detector, where ions pass from the first chamber to the second chamber through a plurality of channels between the first chamber and the second chamber and are detected by the at least one ion detector. The voltages applied to the rods may include a first voltage applied to a first subset of the rods and a second voltage applied to a second subset of the rods, each of first and second voltages containing a DC component and an AC component.