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 mu A. These results are attributed to a relatively high field enhancement factor beta similar to 960 of the CNTs electrodes compared with beta similar to 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.