Radial Differential Mobility Analyzer

Short Name or Variable Name

  • RDMA is a continuous-flow instrument that measures aerosol particle electrical mobility distributions that correspond to particles ~7 nm to ~200 nm diameter. The exact size range depends on flow rate, voltages, air pressure and temperature. The air sample passes through an ion source where the aerosol particles acquire an electrical charge. Particles with the correct charge and mobility are selected in a parallel-plate precipitator, where a voltage is imposed between the plates, then counted with a CN counter. The selected size changes continuously by ramping the voltage through a large range, ~30 to 6000 volts over ~160 s period. RDMA requires an air sample inlet and piping.


Calibration Methods

Monodisperse PSL for size, Gilibrator for flow, RAF standards for P, T, RH

Lead Contact
Mike Reeves