Design of a carbon-nanotube yarn field emitter for micro-focus X-ray generation

Abstract

The field-emission (F-E) characteristics of multi-walled carbon-nanotube (MWCNT) yarn and its contribution to X-ray generation have been investigated in the current work. A dry spinning method was used to fabricateMWCNT yarn from superMWCNTs that had been fabricated by using microwave plasma-enhanced chemical vapor deposition (MW-PECVD). The F-E behavior of the MWCNT yarn followed the Fowler-Nordheim model. Compared to a MWCNT, the MWCNT yarn displayed a significant F-E capability in both the diode and the triode X-ray generation structures. The low-voltage F-E of the MWCNT yarn can be attributed to the field-enhancing effect of the yarn due to its shape and to the contribution of the high-aspect-ratio nanotubes that protrude from the sides of the yarn. The effect of filters on the development of X-ray images has also been demonstrated. The amount of exposure of the samples to X-rays was also manipulated. Results of this study indicate that the MWCNT yarn may be a good candidate for use in low-voltage F-E applications for X-ray imaging.