Patent ID: 8513591

Claim:
An ion mobility spectrometer instrument comprising: a drift tube partitioned into a plurality of cascaded drift tube segments, each defining an ion inlet gate at one end, an ion outlet gate at an opposite end and a first distance between the ion inlet gate and the ion outlet gate, with an ion elimination region defining a second distance between the ion outlet gate of each drift tube segment and the ion inlet gate of the next adjacent drift tube segment, the ion outlet gate of a last one of the drift tube segments coupled by a last ion elimination region to the ion inlet gate of a first one of the drift tube segments such that the drift tube defines therein a closed and continuous ion travel path, an ion source, an ion entrance drift tube segment having an ion inlet coupled to the ion source and an ion outlet coupled to one of the plurality of cascaded drift tube segments, an ion exit drift tube segment having an ion inlet coupled to the one or another one of the plurality of drift tube segments, and an ion outlet, an ion gate arrangement responsive to a first set of one or more ion gate signals to direct ions moving through the drift tube through the one or another one of the plurality of cascaded drift tube segments while blocking the ions from entering the ion exit drift tube segment, and to a second set of one or more ion gate signals to direct the ions moving through the drift tube into the ion exit drift tube segment while blocking the ions from moving through the one or another one of the plurality of cascaded drift tube segments, a number, M, of electric field activation sources each operatively connected to one or more of the plurality of drift tube segments such that, when activated, each establishes a repulsive electric field in at least one of the first M ion elimination regions and in every following Mth ion elimination region, and also establishes an electric drift field in all remaining ion elimination regions and in all of the plurality of cascaded drift tube segments, and a control circuit including a memory having instructions stored therein that are executable by the control circuit to produce the first set of one or more ion gate signals and sequentially activate each of the number, M, of electric field activation sources for a time duration while deactivating the remaining number, M, of electric field activation sources to thereby cause only ions supplied by the ion source that have a predefined ion mobility or range of ion mobilities defined by the time duration to travel through the drift tube, and after the ions have traveled around the drift tube a selected number of times to produce the second set of one or more ion gate signals to draw ions moving through the drift tube out of the drift tube and into the ion exit drift tube segment where the ions exit via the ion mobility spectrometer via the ion outlet of the ion exit drift tube segment.