Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Ion-Molecule Reactions and Ion Kinetics in DC Townsend Discharges in Dielectric Gases

Published

Author(s)

MVVS. Rao, James K. Olthoff

Abstract

The transport of positive and negative ions plays an important role in the initiation and behavior of discharges in gaseous dielectrics. In many cases, the identities, intensities, and kinetic energies of ions are determined by ion-molecule collisions experienced by ions as they are accelerated through the discharge. To help delineate the role of various collisional processes, such as charge-exchange collisions, collisional detachment, and ion conversion, we have measured the kinetic-energy distributions (KEDs) of positive and negative ions formed in dc Townsend discharges generated in O2 and SF6 at high electric field-to-gas density ratios (E/N). The relative abundances and mean energies of the ions are obtained from these measurements, and the effective cross sections for the ion-molecule reactions, in some cases, may be calculated. The availability of ion-molecule collision cross sections for the negative ions formed in O2 and SF6 enable a reasonable understanding of the KED data. However, for these two molecules, attempts to analyze the KED data for these two gases highlight the lack of fundamental ion-molecule cross section data for positive ions formed in these discharges.
Proceedings Title
Proc., Intl. Symp. on Gaseous Dielectrics
Conference Dates
June 2-5, 1998
Conference Location
Virginia Beach, VA

Keywords

ion-energy distributions, ion-molecule reactions, oxygen, SF<sub>6</sub>, Townsend discharge

Citation

Rao, M. and Olthoff, J. (1999), Ion-Molecule Reactions and Ion Kinetics in DC Townsend Discharges in Dielectric Gases, Proc., Intl. Symp. on Gaseous Dielectrics, Virginia Beach, VA, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=21154 (Accessed June 5, 2023)
Created December 31, 1998, Updated October 12, 2021