Numerical analysis of negative corona discharge from the tip of Taylor cone in electrospray*

The use of micro-droplets increases the contact area with plasma and enables efficient reactions. This study focuses on electrospray(ES) as a method to generate plasma and microdroplets simultaneously. We developed a numerical model of corona discharges and ES to elucidate the effect of negative corona discharges on Taylor cone formation and droplet emission. The ES and corona discharge are generated in nozzle-plate electrodes with 3 mm gap in atmospheric pressure air. From the nozzle, liquid is supplied. The ES simulation was performed by solving Navier-Stokes equation and current continuity equation. The discharge was calculated by continuity equations for charged species with Poisson’s equation. 

Owing to the different time scale of a liquid movement and a discharge, it is impractical to perform a simultaneous simulation of corona discharge with ES. We conducted the discharge simulation in a μs time-scale using a snapshot geometry of the cone shape obtained by the ES simulation in a ms time-scale. We demonstrated a Trichel pulse discharge with a liquid Taylor cone, resulting in a peak current value of 1.15 mA for the first pulse. The mechanical effect of Trichel pulse discharge on Taylor cone was evaluated.