Low Electric Field Drift Tube Ion Mobility Analysis for Atmospheric Pressure Plasma

A low voltage compact ion mobility spectrometer type charged particle analyzer is being investigated to test the performance for diagnostics of ion/electron transport in an atmospheric pressure environment. The 44 mm diameter, 53 mm long device consists of a mesh gated shutter, a 35 mm long drift region, and an end-plate detector. By applying a cyclic positive bias followed by a negative bias to the shutter region, subsequent attraction and expulsion of charged species is observed with the applied voltage less than 100 V. Mesh size dependence of the shutter gated current at the detector shows that across 0, 30, 100, and 200 mesh sizes, the 30 mesh size realized the transport of the most number of ions towards the detector. This mesh size also presents a well-defined current-time derivative which allows the measurement of ion mobilities in electric fields with the intensity less than 33.3 V/cm. Analysis of peaks observed after the onset of the positive phase shows the presence of O+ ions in the swarm with a reported experimental mobility of K0 = 2.97 cm2/Vs. ⃝c 2023 The Japan Society of Plasma Science and Nuclear Fusion Research