Carbon nanotubes as electron source in an x-ray tube

Abstract

Field emitters comprised of aligned carbon nanotubes are shown to be promising as a primary electron source in an x-ray tube working in a nonultrahigh vacuum ambience. At a pressure of 2×10−7 Torr, the nanotube emitters continue to emit electrons for more than 1 h, and yield better resolved x-ray images than do thermionic emitters, independently of whether the sample is biological or nonbiological. The near-uniformity in energy distribution of electrons emitted from carbon nanotubes might be related to the improved image quality in the field-emission mode.

Interaction of Palladium Nano-Crystals with Hydrogen During PECVD Growth of Carbon Nanotubes

“…Graphite nano-tubes were grown by the PECVD technique on a 500µm thin wire of Pd, as described previously [2][3][4]. Two devices were tested, one with a large reaction chamber (about 3 liter, fig1 a), another with a large vacuum tank connected with a 0.2mm orifice to the small reaction chamber (about 0.3 liter, fig 1b).…”

“…Since the discovery of carbon nano-tubes (CNT) [1], their processing made a large progress and the possibility of controlled growth of nanotubes stimulated possible applications, for example they can be used as microsize X-ray emitters [2][3], flat displays or STM-tips, or for Hydrogen storage. The plasma-enhanced chemical vapor deposition (PECVD) method [4] is one of the most efficient production methods of nanotubes or their closed variants graphite nano-Fibers (GNF).…”

Carbon nanotubes-properties and applications: a review

“…Electrons are easily emitted from their tips due to the curvature present in the CNTs in the form of pentagons [102,103] or due to the presence of oxidized tips [104,105]. With this principle, CNTs can be used for the fabrication of multiple electronic devices [104], including flat-panel displays, intense light sources, bright lamps [93,106,107], and X-ray sources [46,108]. Although CNTs are good emitters, nanocomposites of CNTs are also excellent electron-emission surfaces which are vacuum stable [109].…”

Highly enhanced and temporally stable field emission from MWCNTs grown on aluminum coated silicon substrate

“…[7][8][9][10][11][12] Due to their exceptionally high aspect ratio, stiffness, electrical conductivity and possibility of growth on various substrates, tremendous efforts have been made for replacing the conventional electron sources by CNT based cold cathodes for applications such as field emission displays (FEDs), field emission microscopes, X-ray tubes, microwave amplifiers etc. [13][14][15][16][17][18] In general, field emission process is governed by a theoretical model proposed by Fowler and Nordheim, which is based on quantum mechanical tunneling. 19 According to this model current density (J) is expressed as:…”