Carbon Nanotube Cold Cathodes for Applications under Vacuum to Partial Pressure in Helium and Dryair

Abstract

Carbon nanotubes are known for their excellent field emission characteristics. This property of carbon nanotubes makes them a good choice for the cold cathode material for many high power applications. In this work carbon nanotubes are studied in order to develop cold cathode material with efficient field emission characteristics. These coatings of nanotubes then will be used for the triggering mechanism of pseudospark switch. In this research work randomly aligned Multi-Walled carbon nanotubes (MWNTs) are fabricated using chemical vapor deposition method (CVD). The MWNTs are fabricated under different growth conditions by varying sputtering times of the catalyst and growth times of CNTs. The change in the densities of MWNTs with different growth conditions is discussed and results are presented. These nanotubes are then tested for their field emission characteristics at different pressures ranging from 5x10-7 Torr to 20x10-3 Torr. The experiments were carried out in different background gases of Helium and dryair. Effects of different gases at different pressures on the field emission properties of carbon nanotubes are studied and results are presented. The lifetime and current stability tests were also performed at 5x10-7 Torr and 20x10-3 Torr and relevant plots are presented. The use of these CNTs as trigger electrode for pseudospark switch is part of another study and only an introduction to pseudospark switches given here.