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Vertically aligned carbon nanotubes (CNTs) are essential to studying high current density, low dispersion, and high brightness. Vertically aligned 14 × 14 CNT emitters are fabricated as an island by sputter coating, photolithography, and the plasma-enhanced chemical vapor deposition process. Scanning electron microscopy is used to analyze the morphology structures with an average height of 40 µm. The field emission microscopy image is captured on the microchannel plate (MCP). The role of the microchannel plate is to determine how the high-density electron beam spot is measured under the variation of voltage and exposure time. The MCP enhances the field emission current near the threshold voltage and protects the CNT from irreversible damage during the vacuum arc. The high-density electron beam spot is measured with an FWHM of 2.71 mm under the variation of the applied voltage and the exposure time, respectively, which corresponds to the real beam spot. This configuration produces the beam trajectory with low dispersion under the proper field emission, which could be applicable to high-resolution multi-beam electron microscopy and high-resolution X-ray imaging technology.

The focusing electrode plays an important role to reduce the electron beam trajectory with low dispersion and high brightness. This article summarizes the importance of the vertically aligned multi-walled carbon nanotube effect with the focusing electrode. First of all, the effect of electron beam trajectory is studied with the different heights, hole sizes, and applied voltage of the focusing electrode by the opera 3D simulation. The field emission electron beam spot is captured in the microchannel plate which helps to reduce the signal noise effect and damage of CNT tips by the joule heating effect. The high-dense bright spot is optimized at the focusing electrode hole size of 2 mm, and the height of 1 mm from the gate mesh electrode at the low bias voltage of -200 V without the loss of current. The FWHM of the electron beam is calculated 0.9 mm with its opening angle of 0.90 which could be applicable in high-resolution multi-electron beam microscopy and nano-focused X-ray system technology.

Nondestructive technology (NDT) is the most popular method for detecting defects inside an object without harming it. A 3D tomography algorithm toolbox and an x-ray imaging system are the essential components of NDT. We fabricated a high-resolution cold cathode electron beam (HRC-beam) based on vertically aligned carbon nanotubes to accomplish this objective. Using an HRC-beam, multiple angle projection images were captured in an x-ray imaging system. This x-ray source's horizontal and vertical focal spot sizes were 0.57 and 0.49 mm, respectively. Using the homemade 3D tomography algorithm toolbox, all the multiple projection images were recreated in a 3D volume. This toolbox employs algorithms such as the radon transform and the inverse radon transform to generate the 3D volume. The matlab r2022b program was used to execute the algorithm. This study explains the development of a three-dimensional volume and the inspection of the 3D volume in a slice view using a high-resolution cold cathode electron beam and the 3D tomography algorithm toolbox. A large phantom cable was used to evaluate 3D reconstruction and void inspection inside the large phantom cable.

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.