Ion current density profiles in negative corona gaps versus EHD confinements

Abstract

This paper deals with the electric and hydrodynamic confinement of negative ions in a point-to-plane corona discharge gap. Radial ion current density profiles have been measured on the earthed planar electrode, drilled in the axis of the point. The experimental setup is first validated by comparison with the Warburg's law without injected gas flow rate. The gas injected in the gap and blown from the discharge gap through the hole located at the centre of the plane affects neither the electric field close to the point nor the subsequent electric wind. However, it leads to the confinement of ions flux towards the central symmetry axis in the low electric field region up to a critical gas velocity, which for no more effect is measurable. Hence, electro hydro-dynamics confinement of ions can be achieved by limiting the outward radial expansion of ions to increase ion current densities on specific locations close to the low field planar electrode.

Review on water electro-sprays and applications of charged drops with focus on the corona-assisted cone-jet mode for High Efficiency Air Filtration by wet electro-scrubbing of aerosols

“…The critical size-mobility relation from different DC corona and/or AC Dielectric Barrier Discharges for bipolar charging still has to be addressed for high aerosol flowrate applications. Then, high flowrate and particle loading could be studied taking into account the evolution of the sizemobility relation with concentration, expected from self-repulsion losses of such unipolar aerosol clouds reported for charge density higher than 10 7 e.cm -3 (Whitby K. T. , 1961;Whitby K. T. et al, 1965;Kasper G., 1981;McMurry et al, 1985;Stratmann et al, 1992;Bouarouri et al, 2016).…”

Post-corona unipolar chargers with tuneable aerosol size-charge relations: Parameters affecting ion dispersion and particle trajectories for charger designs

“…From 10 to 100 µA, whatever the particle size is, the mean charge per particle only increases by about 8-15 % for two reasons. The maximal ion density at the inlet of the charging volume is not proportional to the discharge current (Bouarouri et al 2016). This is mainly due to the faster ion dispersion by unipolar self-repulsion at larger discharge current that increases ion losses on the walls of the ion injector and of the charging volume.…”

“…The discharge regime (Trichel with current pulses or Corona with a continuous current) as well as the evolution of the current are investigated with an oscilloscope measuring the discharge current (Id) in the external circuit, with measurement time constant from ns (using a 25  resistor) to s (10 k resistor), as reported in (Bouarouri et al 2016).…”