Cold Electron Beam Research Articles

Enhancing starch functionality through synergistic modification via sequential treatments with cold plasma and electron beam irradiation

The impact of dual sequential modifications using radio-frequency (RF) plasma and electron beam irradiation (EBI) on starch properties was investigated and compared with single treatments within an irradiation dose range of 5–20 kGy. Regardless of sequence, dual treatments synergistically affected starch properties, increasing acidity, solubility, and paste clarity, while decreasing rheological features with increasing irradiation dose. The molecular weight distribution was also synergistically influenced. Amylopectin distribution broadened particularly below 10 kGy. Amylose narrowed its distribution across all irradiation doses. This was due to dominating EBI-induced degradation and molecular rearrangements from RF plasma. With the highest average radiation-chemical yield (G) and degradation rate constant (k) of (2.12 ± 0.14) × 10−6 mol·J−1 and (3.43 ± 0.23) × 10−4 kGy−1, respectively, upon RF plasma pre-treatment, amylose underwent random chain scission. In comparison to single treatments, dual modification caused minor alterations in spectral characteristics and crystal short-range order structure, along with increased granule aggregation and surface irregularities. The synergistic effect was dose-dependent, significant up to 10 kGy, irrespective of treatment sequence. The highest synergistic ratio was observed when RF plasma preceded irradiation, demonstrating the superior efficiency of plasma pre-treatment in combination with EBI. This synergy has the potential to lower costs and extend starch's technological uses by enhancing radiation sensitivity and reducing the irradiation dose.

Permanent helical micro-undulators for x-ray free electron lasers

Helical Halbach undulators, formed by four alternately axially and radially magnetized rare-earth helices, produce a stronger field than two planar Halbach undulators with perpendicular polarization. Hybrid undulators of two longitudinally premagnetized rare-earth helices and two initially unmagnetized steel (or vanadium permendur) helices produce an equal or higher field and are easier to implement. We made sure that the required helices with a period of down to 3 mm or even less could be manufactured with high precision using Wire Electric Discharge Machining. According to the simulation results, when using identical electron bunches with moderate initial spreads in energy and angles, the gain in x-ray free electron laser (XFEL) power from replacing planar micro-undulators with the helical micro-undulators under consideration can be significantly greater than predicted by the simplest 1D theory with a cold electron beam. This makes such micro-undulators promising for creating compact XFELs of various types, both based on modern linear accelerators and plasma wakefield accelerators.

Effect of beam and gate offset size on x-ray focal spot resolution of a cold cathode electron beam

In x-ray imaging, high resolution is essential, particularly in sectors such as medical and industries where the need for nondestructive defect detection is required. Previous research has shown that altering beam design and the number of gates offset holes has an impact on focal spot size (FSS). However, the specific effects of beam size and offset size were not thoroughly assessed. In the present study, the influence of beam size and gate offset size was evaluated by utilizing a cold cathode electron beam. Various beam sizes were employed to achieve a small FSS, and subsequently, the smallest beam was utilized to examine the impact of gate offset size. In doing so, the smallest FSS of 0.25 mm vertical and 0.33 mm horizontal was attained without the utilization of any additional focusing lens. This illustrates that by adjusting the beam size and gate offset size, it is possible to attain a small FSS, facilitating the development of an economically viable x-ray imaging beam.

Impact of electrical aging on x-ray image quality and dose rate with vertically aligned carbon nanotube based cold cathode electron beam (C-beam)

The adoption of vertically aligned carbon nanotubes (VACNTs) as electron emitters in x-ray generation has opened a new path for medical imaging technology advancement. With their outstanding electron emission capabilities, VACNTs provide a distinct advantage in miniaturizing and improving the performance of x-ray devices. This research focuses on the effect of electrical aging on x-ray imaging quality and the dose rate while using VACNTs as the electron source. The study includes a thorough examination of the electrical aging effects on VACNT-based x-ray systems, with an emphasis on changes in emission characteristics, beam stability, and the resulting variations in x-ray output. Experiment results show that electrical aging has a considerable impact on the performance of VACNT-based x-ray sources, with visible changes in electron emission parameters and subsequent consequences on x-ray imaging quality. Furthermore, the study investigates the relationship between electrical aging and the x-ray dose rate, providing vital insights into radiation exposure optimization in medical diagnostics.

The impact of electron beams on the arbitrary amplitude electron–acoustic solitons in a nonthermal plasma

This study examines the nonlinear dynamics of high-frequency electron–acoustic waves (EAWs) in a collisionless, unmagnetized plasma consisting of several components, including inertial cold electrons, an inertial electron beam, and inertialess Cairns-distributed hot electrons in addition to background stationary ions. We use a nonlinear pseudopotential (Sagadeev potential) method to investigate the possibility of stationary-profile electron–acoustic solitons (EASs). In this study, the nonthermal parameter, the temperature ratio between hot and cold electrons, density ratios, and electron beam parameters are carefully examined to see how they change the features of EASs. As the nonthermality of hot electrons rises, the beam speed decreases, the density ratio of the beam to the cold electron increases, and the existence domain for EASs gets bigger. The current theoretical model shows a link between the wideband noise seen in Geotail satellites and the plasma sheet boundary layer in Earth's magnetosphere.

Slipping instability of an inhomogeneous relativistic electron beam

The charged particle beams, such as electrons, ions, and plasma compression flow, have received considerable attention due to their applications in science and technology; therefore, studying the stability of these beams is of particular importance. Here, we examine theoretically the stability properties of a cold relativistic electron beam with a transverse velocity shear and non-uniform density profile. We consider a plane-parallel beam propagating along an external magnetic field and evaluate its macroscopic equilibrium state. We derive the dispersion relation of the slipping instability based on the linear electrodynamics of an inhomogeneous plasma and kinetic theory. In this model, the oscillation spectrum and the growth rate are derived by using the eikonal equation and the quasi-classical quantization rule. A linear velocity shear and a non-linear density gradient are assumed. Furthermore, we analyze numerically the dispersion relation of the slipping instability. The impacts of the inhomogeneity parameter and the relativistic factor on the properties of the slipping instability are discussed.

The Saturation Mechanism in a two-stream free-electron laser based upon a rectangular hybrid wiggler

This paper presents a one-dimensional nonlinear simulation of a square hybrid two-stream free electron laser (TSFEL) consisting of an axial magnetic field guide. It is supposed that the two cold relativistic electron beams differ in energy, while the electron beam’s self-fields, and radiation wave slippage relative to electron beams are neglected. A set of differential equations of the first order of coupled nonlinearity, obtained from the combination of Maxwell’s equations and Lorentz’s equations, can be numerically solved using a Runge–Kutta algorithm of fourth-order based on slowly varying amplitudes and wavenumbers approximation. According to the results of the calculations, the increase in the axial magnetic field will increase the efficiency in group I orbits while the saturation length decreases. The results for group II orbits are different from those of group I, so the efficiency decreases with the increasing axial magnetic field. There is, however, an increase in saturation length. Additionally, it is found that prebunching significantly reduces the length of saturation. A comparison of radiation saturation in an FEL and a TSFEL indicates that a TSFEL has a higher efficiency than an FEL. In contrast, the TSFEL has shorter saturation lengths.

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

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.

Nonlinear ion acoustic wave structure in electron–ion plasma in presence of fully relativistic electron beam

Analytical description of large amplitude nonlinear ion acoustic (IA) waves in the presence of a cold relativistic electron beam is presented. The pseudopotential method is adopted to observe the effects of various parameters like beam density, ion temperature, etc. on the IA wave structures. Furthermore, the maximum amplitude of the IA wave is estimated, and its variation with fully relativistic electron beam parameters is investigated. The maximum allowed amplitude of the wave is found to decrease with the increase in the electron beam density as well as in the ion temperature. The Mach number has the effect to increase the maximum amplitude of the electric field.

Solitons in a cold electron beam plasma

Necessary and sufficient conditions for the existence of dissipative electron-acoustic solitons in a cold electron beam plasma with superthermal trapped electrons described by the Schamel equation are derived in this paper. Soliton solutions to the Schamel equation are constructed using formal analytical techniques which yield counter-intuitive conditions for the existence of these solutions. The existence conditions are derived in terms of system parameters and initial conditions. Computational experiments are used to validate the obtained results.

Extreme Ultraviolet Lighting Using Carbon Nanotube-Based Cold Cathode Electron Beam.

Laser-based plasma studies that apply photons to extreme ultraviolet (EUV) generation are actively being conducted, and studies by direct electron irradiation on Sn for EUV lighting have rarely been attempted. Here, we demonstrate a novel method of EUV generation by irradiating Sn with electrons emitted from a carbon nanotube (CNT)-based cold cathode electron beam (C-beam). Unlike a single laser source, electrons emitted from about 12,700 CNT emitters irradiated the Sn surface to generate EUV and control its intensity. EUV light generated by direct irradiation of electrons was verified using a photodiode equipped with a 150 nm thick Zr filter and patterning of polymethyl methacrylate (PMMA) photoresist. EUV generated with an input power of 6 W is sufficient to react the PMMA with exposure of 30 s. EUV intensity changes according to the anode voltage, current, and electron incident angle. The area reaching the Sn and penetration depth of electrons are easily adjusted. This method could be the cornerstone for advanced lithography for semiconductor fabrication and high-resolution photonics.

Gate offset and emitter design effects of triode cold cathode electron beams on focal spot sizes for x-ray imaging techniques

We report on the structural effects of a carbon nanotube based cold cathode electron beam (C-beam) module on focal spot sizes (FSSs) for high resolution x-ray imaging applications without additional focusing components. A simple combination of vertically aligned carbon nanotubes and gate mesh structure achieved FSS of 252 and 410 μm for longitudinal and transverse directions, respectively. As design parameters of the modules, gate offsets, gate hole pitch, and emitter area effects of C-beam modules on FSS were optimized. We expect that our simple but sophisticated C-beam module structure will pave next generation x-ray devices not only for high quality x-ray imaging but cost-effective ways for mass production.

Emission Features and Structure of an Electron Beam versus Gas Pressure and Magnetic Field in a Cold-Cathode Coaxial Diode

The structure of the emission surface of a cold tubular cathode and electron beam was investigated as a function of the magnetic field in the coaxial diode of the high-current accelerator. The runaway mode of magnetized electrons in atmospheric air enabled registering the instantaneous structure of activated field-emission centers at the cathode edge. The region of air pressure (about 3 Torr) was determined experimentally and via analysis, where the explosive emission mechanism of the appearance of fast electrons with energies above 100 keV is replaced by the runaway electrons in a gas.

Low-energy electron beam has severe impact on seedling development compared to cold atmospheric pressure plasma

Sprouts are germinated seeds that are often consumed due to their high nutritional content and health benefits. However, the conditions for germination strongly support the proliferation of present bacteria, including foodborne pathogens. Since sprouts are consumed raw or minimally processed, they are frequently linked to cases of food poisoning. Therefore, a seed decontamination method that provides efficient inactivation of microbial pathogens, while maintaining the germination capacity and quality of the seeds is in high demand. This study aimed to investigate and compare seed decontamination by cold atmospheric-pressure plasma and low-energy electron beam with respect to their impact on seed and seedling quality. The results show that both technologies provide great potential for inactivation of microorganisms on seeds, while cold plasma yielded a higher efficiency with 5 log units compared to a maximum of 3 log units after electron beam treatment. Both techniques accelerated seed germination, defined by the percentage of hypocotyl and leaf emergence at 3 days, with short plasma treatment (< 120 s) and all applied doses of electron beam treatment (8–60 kGy). However, even the lowest dose of electron beam treatment at 8 kGy in this study caused root abnormalities in seedlings, suggesting a detrimental effect on the seed tissue. Seeds treated with cold plasma had an eroded seed coat and increased seed wettability compared to electron beam treated seeds. However, these effects cannot explain the increase in the germination capacity of seeds as this was observed for both techniques. Future studies should focus on the investigation of the mechanisms causing accelerated seed germination and root abnormalities by characterizing the molecular and physiological impact of cold plasma and electron beam on seed tissue.

Investigation of the Effect of Structural Properties of a Vertically Standing CNT Cold Cathode on Electron Beam Brightness and Resolution of Secondary Electron Images.

Carbon nanotube (CNT)-based cold cathodes are promising sources of field emission electrons for advanced electron devices, particularly for ultra-high-resolution imaging systems, due to their high brightness and low energy spread. While the electron field emission properties of single-tip CNT cathodes have been intensively studied in the last few decades, a systematic study of the influencing factors on the electron beam properties of CNT cold cathodes and the resolution of the secondary electron images has been overlooked in this field. Here, we have systematically investigated the effect of the structural properties of a CNT cold cathode on the electron beam properties and resolution of secondary electron microscope (SEM) images. The aspect ratio (geometric factor) and the diameter of the tip of a vertically standing CNT cold cathode significantly affect the electron beam properties, including the beam size and brightness, and consequently determine the resolution of the secondary electron images obtained by SEM systems equipped with a CNT cold cathode module. Theoretical simulation elucidated the dependence of the structural features of CNT cold cathodes and electron beam properties on the contribution of edge-emitted electrons to the total field emission current. Investigating the correlations between the structural properties of CNT cold cathodes, the properties of the emitted electron beams, and the resolution of the secondary electron images captured by SEM equipped with CNT cold cathode modules is highly important and informative as a basic model.

Whistler and Broadband Electrostatic Waves in the Multiple X‐Line Reconnection at the Magnetopause

AbstractWe investigate whistler‐mode waves and broadband electrostatic waves (EWs) within an ion diffusion region (IDR) at the magnetopause. The quasi‐parallel whistlers are observed in the separatrix regions associated with the electron anisotropy or loss cone, while the oblique whistlers, the Buneman‐type waves, and the oblique EWs are observed in the center of the current sheet associated with the accelerated electron or ion beams. The whistlers are linked with Buneman‐type waves by the electron Pacman distribution rather than the wave‐wave process. The accelerated cold electron beams excite the Buneman‐type instabilities and make the anisotropy or loss cone of hot electrons less apparent, which led to the conversion of the whistlers from quasi‐parallel to oblique. Additionally, the oblique EWs are associated with the ion beams produced by the multiple X‐line reconnection. These results provide a further understanding of the relation between plasma waves and plasma kinetics in the IDR.

Emergence of cold plasma and electron beam irradiation as novel technologies to counter mycotoxins in food products

Today, mycotoxins are considered a serious risk for human health and the economy around the world. Hence, dealing with them in such a way as to minimise damage to food and plant materials has become an important issue. Cold atmospheric plasma and electron beam irradiation are updated and non-thermal technologies, which are recently used in detoxification of mycotoxins. Both of these technologies have several unique features that turn them into efficient methods for degrading mycotoxins. Therefore, the main purpose of the present study is exhibiting the detoxification power of these methods and parameters affecting their activity. Besides, their advantages, generating systems, activity mechanism, and the toxicity of degradation products are also reviewed.

Scanning electron imaging with vertically aligned carbon nanotube (CNT) based cold cathode electron beam (C-beam)

A novel cold cathode electron beam based on carbon nanotube (CNT) as an electron source has been developed. The direct grown emitters fabricated as electron source have a huge potential for an electron microscope. An electron sources for high-resolution imaging requires some important parameters such as probe size, emission current, convergence angle, and beam brightness. These parameters influence the performance of an electron microscope, which in turn is heavily is dependent on the electron emission source.In the present work, direct growth CNT, a method of fabrication of emitter as an electron source for high-resolution imaging was studied. This CNT field emitters which has a spherical emitter tip as grown on Si substrate has superior hardness. A direct grown CNT emitter can draw a few micro-amperes of current. The single-CNT emitter shows 9.26 × 1010 A sr−1 m−2 V−1 of reduced brightness at 1.1 μA of emission current and a 10 μm of beam spot diameter on phosphor screen in a diode configuration. These results can be confirmed by SOURCE 2D simulation and also, the electron beam trajectory could be predicted. Finally, we fabricated an optimized electron beam module with CNT cold cathode and measured secondary electron imaging of copper grid mesh with the beam.

Kinetic theory of low-voltage beam discharge instability in rare gases

The kinetic theory of a low-voltage beam discharge instability in He is developed in the conditions, when the distance between electrodes is of the order of electron–atom collision length and the density of electrons in a primary beam is up to ten percent of the plasma density. The dispersion equation and its numerical and analytical solutions are obtained. The stability loss of this discharge is described in the framework of the problem with initial and boundary conditions. A significant dispersion is found in the propagation of harmonic disturbances in this system. On the basis of the developed theory, the areas of applicability of the hydrodynamic approach to the consideration of the system “cold electron beam - cold plasma” are elucidated. The theory significantly expands the range of parameters of the electron beam–plasma system, where a quantitative description of the spatial and temporal dynamics of wave propagation in such a system is possible. In the well-known special cases, such as a “weak electron beam - cold plasma,” the results obtained coincide with the data of other authors.

Effect of Casting and Additive Manufacturing on the Microstructure and Mechanical Property of Al-Cu Composites

The TiB2 reinforced Al-5Cu composites was manufactured by additive manufacturing with two kind of heat sources, i.e., cold metal transfer (CMT) and electron beam melting (EBM). The TiB2 particles were in nano-sized with some submicron-sized particle clusters , and their morphologies were round and near round without sharp angles. It was found that the introduce of TiB2 particles improved the mechanical properties of Al-5Cu alloy obviously. The results demonstrated that both the additive manufacturing methods of cold metal transfer (CMT) and electron beam melting (EBM) could improve the microstructure of the composites significantely. Compared with the traditional casting, Al-5Cu alloy the grain sizes of the TiB2 reinforced Al-5Cu composites decreased from larger than 100 μm to 40 μm with CMT process and 25 μm with EBM process. The hardness of the TiB2 reinforced Al-5Cu composites with EBM after heat treatment could be reached to 153 HV10. The refined grains and high hardness of the TiB2 reinforced Al-5Cu composites with EBM additive manufacturing technique verified that AM technology is a promising way to optimize the microstructure and mechanical properties of Al-Cu composites.