Bradbury-Nielsen gate electrode potential switching modes optimizing the ion packet time width in an ion mobility spectrometer

The methods minimizing duration of the output pulse of the ion mobility spectrometer at its maximum intensity were proposed in order to increase the instrument resolution. The optimal duration of the enabling pulse matched with the gate characteristics and ensuring the minimum time width of output ion packet with maximum intensity was chosen. The following operation modes of the Bradbury-Nielsen gate were considered: 1) time compression of the transmitted ion packet by pulsed increase of the potentials at the some set of wires; 2) instantaneous switching the potentials at the adjacent wires and 3) combination of the instantaneous switching of the potentials on the adjacent wires followed by the time compression of a transmitted ion packet. It was shown that the proposed gate modes ensure minimization of the output ion packet duration and increasing of the ion mobility spectrometer resolution. The estimated resolution of the ion peaks doubles and may reach 200 under considered conditions, space charge not taken into account.