Novel technique to control the focal spot size using carbon nanotube based cold cathode electron beam (C-beam) architecture

Abstract

This article discusses the development of a cold cathode electron beam (C-beam) based on vertically aligned carbon nanotubes (VACNTs) and the optimization of field emission (FE) from C-beam architecture design. The characteristics of the electron beam are typically required to match the applications of interest. To study the FE, five distinct multi-array emitter island designs, viz., 65 × 65, 75 × 75, 90 × 90, 100 × 100, and 240 × 240  μm2, were fabricated. The island 240 × 240  μm2 (single island) was divided into a group of four subislands each with dimensions 65 × 65, 75 × 75, 90 × 90, and 100 × 100  μm2. We explored the field-screening effect of these different island designs using experiments and modeling, and we discovered that the size of the island had a significant impact on the FE properties. Moreover, we found that the island’s size significantly affected its I–V properties, with a 75 × 75  μm2 island offering 0.7 mA anode current the best emission current among other islands. Additionally, tungsten cross wire (EN 12543-5), a typical resolution testing object, had its focal spot size (FSS) measured using x-ray imaging, and the lowest FSS of 0.45 and 0.49 mm in both vertical and horizontal directions was obtained. This innovative method has a great deal of promise for developing the next generation of VACNT-based electron sources.