Instrumentation

Mass Analyzer Using an Alternating Electric Field with a Pause Period: Concept and Simulation

In this mass analyzer, pulsed ions are introduced into a separation space during a pause period of the alternating electric field. Furthermore, as defined, the measured ionic species exits from the separation space during the next pause period after receiving the action of the alternating electric field for one period. At this time, the ions of the measured ionic species are energy-focused and separated from the others by the difference in displacement caused by the electric field. In the concept section, the mass analyzer and the alternating electric field were illustrated, and the conditions that the measured ionic species should satisfy were clarified. An equation giving the displacement magnitude of the measured ionic species after one period was derived, showing that the mass separation is performed based on m/z. An equation giving the mass resolution was derived from this equation. In the simulation and discussion section, the mass separation in the alternating electric field and the energy focusing of the ions of the measured ionic species were demonstrated by numerical calculations. A scanning method that changes the period of the alternating electric field was demonstrated, showing that there is no limit to the m/z range that can be analyzed. Besides, it was demonstrated that ionic species in a required m/z range can be analyzed simultaneously with the introduction of one packet of pulsed ions. It was shown that measurement operations can be repeated with no or a little wasted time. Complementarily, the direction-focusing performance of the electric sector was examined.