Optimization of the parameters of a carbon nanotube-based field-emission cathode

• Published in: Technical physics Vol. 56; no. 4; pp. 540 - 545
• Main Authors: Bocharov, G. S., Eletskii, A. V., Sommerer, T. J.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01.04.2011; Springer
• Subjects: Accelerators; Classical and Continuum Physics; Electric properties; Electrical conductivity; Electron and Ion Beams; Nanotubes; Physics; Physics and Astronomy; Average Electric Field; Heat Conduction Equation; Emission Current Density; Field Emission Cathode; Transport Coefficient
• ISSN: 1063-7842; 1090-6525
• DOI: 10.1134/S1063784211040086

A procedure for optimizing a field-emission cathode based on carbon nanotubes (CNTs) is developed. An array of identical equidistant vertical CNTs is considered. The optimization procedure takes into account the effect of screening of an electric field by neighboring nanotubes by solving a Laplace equation and the thermal instability of nanotubes, which limits the emission current density of a nanotube, by solving a heat conduction equation. The relation between the emission current and the applied voltage is described by the Fowler-Nordheim relationship containing the CNT tip temperature as a parameter. Upon optimization, the optimum distance between CNTs that ensures the maximum emission current density is calculated. The calculation results demonstrate that this parameter depends substantially on both the applied voltage and the nanotube geometry. These dependences are weakly sensitive to the choice of the transport coefficients (thermal conductivity, electrical conductivity) of nanotubes.