Flow driven transmission of charged particles against an axial field in antistatic tubes at the sample outlet of a Differential Mobility Analyzer

Electrophoretic losses at the outlet of Differential Mobility Analyzers result from the need to transport the aerosol from the high voltage VBias typically applied to the inner electrode, to the ground potential at which a particle detector is usually connected. Here we examine the sample transmission efficiency η for mobility-selected ions brought to ground through a commercial Static Dissipative Polyurethane tube. η(VBias) is defined as the ratio of the ion current transmitted through the tube with bias voltage VBias over that transmitted when VBias=0. We find η values close to unity under common DMA operational conditions. η is measured also under adverse fields strong enough for all charged particles to be lost, with a sample transmission efficiency comparable to that expected for a uniform velocity profile within the tube. Outlet tube Reynolds numbers are examined in the range 446