Dependence of Gas Discharge Breakdown Voltage on Gas Composition Using Carbon Nanotube Electrode

Abstract

When a voltage applied between a pair of metal electrodes is increased in gas atmosphere, gas discharge breakdown occurs at a certain voltage (a breakdown voltage). This voltage depends on gas species. In other words, gas sensing possible by measuring their breakdown voltages. However, voltage for gas discharge breakdown using conventional metal electrode is generally high under atmospheric pressure. Thus, reduction of the discharge voltage is desirable for the application mentioned above. This study aims at considering possibility to develop gas sensing method by detecting gas discharge breakdown occurring at a relatively low voltage. Electrodes on which carbon nanotubes (CNTs) were attached were used for this purpose. CNTs possess fibrous shapes with nano-sized tip radii. This shape generates very high electric field on the tip. The high field enables reduction of the breakdown voltage. Our results showed that the electrode with CNTs gave dependence of gas discharge breakdown voltages on gas species with relatively lower applied voltages. The breakdown voltage linearly changed with respect to composition ratios of gas mixtures. It is considered that these characteristics originate in field emission electrons from the CNTs.