Discharge characteristics of a nano-sized electrode with aligned carbon nanotubes grown on a tungsten whisker tip under various gas conditions

Vertically aligned multiwalled carbon nanotubes (CNTs) were grown on a tungsten (W) tip by thermal chemical vapour deposition, applying a negative biasing voltage to the W tip in a pin-plate electrode configuration. The CNT electrodes, due to their nano-sized tip radii, create very high electric fields, and reduce the breakdown voltage significantly. Comparing the CNTs-grown W tip electrode with the W tip electrode, the ignition voltage for the former case decreased from 230 to 181 V, while the saturation current increased from 12 to 20 μA. These results are attributed to a relatively high field enhancement factor β ∼ 960 of the CNTs electrodes compared with β ∼ 60 for the simple W tip. There are also significant differences between the W tip electrodes with and without CNTs in the values of the igniting voltage and discharge current, when the W tips are used as a cathode.