Eur. Phys. J. D 50, 297-305 (2008)
https://doi.org/10.1140/epjd/e2008-00238-4

Dependence of negative ion formation on inhomogeneous electric field strength in atmospheric pressure negative corona discharge

International Graduate School of Arts and Sciences, Yokohama City University, Yokohama, 236-0027, Japan

Corresponding author: ^a takayama@yokohama-cu.ac.jp

Received: 30 June 2008
Revised: 8 November 2008
Published online: 12 December 2008

Abstract

The dependence of negative ion formation on the inhomogeneous electric field strength in atmospheric pressure negative corona discharge with point-to-plane electrodes has been described. The distribution of negative ions HO^-, NO_x^- and CO_x^- and their abundances on the plane electrode was obtained with a mass spectrometer. The ion distribution on the plane was divided into two regions, the center region on the needle axis and peripheral region occurring the dominant NO_x^- and CO_x^- ions and HO^- ion, respectively. The calculated electric field strength in inhomogeneous electric field established on the needle tip surface suggested that the abundant formation of NO_x^- and CO_x^- ions and HO^- ion is attributed to the high field strength at the tip apex region over 10⁸ Vm^-1 and the low field strength at the tip peripheral region of the order of 10⁷ Vm^-1, respectively. The formation of HO^-, NO_x^- and CO_x^- has been discussed from the standpoint of negative ion evolution based on the thermochemical reaction and the kinetic energy of electron emitted from the needle tip.