Applications of Dielectric Barrier Discharges as aerosol charger

Aerosol particle charging is involved in many scientific and industrial applications and especially in measurements based on electrostatic classification. Non-thermal Atmospheric Pressure Electrical Discharges are an efficient way to charge particles. We report here the charge distribution of aerosol at the exit of a Dielectric Barrier Discharges (DBD) and discuss the potential applications. The DBD reactors are made of two planar electrodes both covered by a dielectric material that are separated by a gas gap spacing. The dielectric barrier prevents arc formation and implies an alternative polarization of the system (typically a few kV at 50 Hz–1 MHz). In air, at atmospheric pressure, the plasma occur as thin and brief filaments discharge (a few 10’s of μm, a few 10’s of ns) crossing the gap and homogeneously distributed over the electrode surfaces. Thus, DBD produce high transient charging conditions (bipolar ions densities and electric field) in which particles are injected. Post discharge ions densities and mobilities have been investigated versus plasma and hydrodynamics parameters to reach iso-densities. In most cases, the net post discharge ion current is positive. Below 90 °C both positive and negative are constant with mean mobility of 1.41 and 1.78 cm.V.s respectively (Bourgeois et al., 2009). The frequency of the applied voltage controls the amplitude of the oscillating particle trajectory and can be adjusted to limit or enhance electro-deposition in the DBD (Jidenko & Borra, 2005, 2012). Particle charge distributions and losses have been measured for monodisperse aerosols from 20 nm to 900 nm injected in the DBD.