Asymmetric high frequency square wave generator with DC component control for ion mobility spectrometers

摘要

The problem of the ion separation/detection has applications in many fields, like: nuclear technology, detection of contraband and explosives, security and military domain. In weak electric fields, the ratio (K) of the ion speed (v) over electric field strengths (E) is typical for each ion with the given mass (m) and electrical charge (e). This ratio, known as mobility (K), can be measured using the ldquotime of flight (Deltat)rdquo. Reciprocal, if a certain time of flight is found, that means that this substance is present. By stronger electric field, mobility (K) changes. If an ion was carried through the plates of a small capacity, using a drift gas, the AC asymmetric high frequency voltage wave-form, called ldquodissipative voltage DVrdquo produces an ion motion toward one plate or to other. Another DC voltage: the ldquocompensation voltage CVrdquo may ensure the avoiding of the plate contact and the ion may traverse this distance. Only the ions with certain physical properties may pass through the plates, giving a small ion current. In this mode, a ion of interest may be detected/ separated.