This paper examines multi-tip ZnO-based field emitters with varying thicknesses of an ultrathin In2O3 coating (from 1 to 5 nm). The optimum coating thickness was found. A general trendline method based on the Murphy-Good equations for metallic and semiconductor emitters was used to process the experimental current-voltage (I-V) characteristics and extract the key emission parameters. UPS and Kelvin probe spectroscopy were used to determine the coating work function.

This work presents a computational approach to model field electron emission from metal-like emitters by incorporating crystallographic work function anisotropy. A multiscale method combines atomistic surface reconstruction with finite-element electrostatic simulations, assigning local work function values based on Miller indices and interpolating them into a continuous distribution. Applied to a hemisphere-on-cylindrical-post geometry, the model reveals strongly nonuniform emission patterns and significant deviations from conventional uniform work function predictions. The results show that neglecting anisotropy leads to substantial differences in emission current estimates, demonstrating that accurate prediction requires explicit consideration of spatially varying local work function distributions in realistic tungsten emitters.

This study dealt with field emission characteristics of composite emitters fabricated from copper powder mixed with multi-walled carbon nanotubes. The composite materials were sintered at high pressure (~5.5 GPa) under various temperature conditions: 25, 500, and 1000 °C. Influence of the sintering temperature on the microstructure and field emission performance of the resulting emitters was examined. The obtained results demonstrate the potential of high-pressure sintering as a viable method for fabricating efficient copper- carbon nanotube composite emitters.

Concentric-ring field emitter architectures are relevant to vacuum micro- and nanoelectronic applications. In view of field electron emission applications for these ring-emitters, a central question is to determine under what geometric conditions these structures, when subjected to an external electrostatic field E (appl), can sustain a uniform macroscopic current despite the electrostatic depolarization that couples neighboring rings. We address this question by computing stationary configurations for a cathode composed of concentric emitting rings of width omega and spacing c, with innermost height h(1)(star) and each kth ring located at radius rho(k). A robust finite-element-based numerical procedure is developed to obtain the optimized heights h k star that sustain a prescribed uniform arc current. Using the dimensionless spacing s = c / h(1)(star)and the inner-ring aspect ratio 2 h(1)(star) / omega, we analyze the normalized profiles h k star / h(1)(star) as functions of rho(k) / h(1)(star). Our results reveal a systematic curvature transition governed by the interplay between the isolated-emitter characteristic field and the depolarization correction: for s less than or similar to 1, depolarization decreases rapidly with the radial position rho(k) and all profiles remain concave down, whereas for s greater than or similar to 1, the slower radial decay of depolarization generates an inner convex region followed by an outer concave region. This geometric transition sets the nontrivial dependence of E (appl )on spacing and aspect ratio, showing that uniform emission cannot be inferred from geometry alone without explicit optimization. For moderate inner-ring aspect ratios ( 2 h(1)(star) / omega = 15 - 20), E (appl) ( s ) exhibits a maximum at s(m) similar or equal to 0.35, increasing the required field by 4%-5% relative to the closely spaced regime and by about 35 % relative to large spacings where depolarization becomes negligible. For taller inner rings ( 2 h(1)(star)/ omega greater than or similar to 40), curvature dominates and E (appl) ( s ) is strictly monotonic over the explored spacing range. Therefore, we identify ( 2 h(1)(star) / omega , s ) as the key geometric parameter pair governing uniform-current operation and provide quantitative criteria for selecting the macroscopic field E (appl) required to deliver specified macroscopic currents in concentric cold-cathode architectures.

A detailed study of promising flexible field emitters based on a nanocomposite polyvinyl alcohol with multiwalled carbon nanotubes was conducted. The properties of the emitter were measured in three configurations: a flat surface, a vertical edge, and a loop. Sample characterization in field emission projectors was accompanied by scanning electron, atomic-force, and Kelvin probe force microscopies as well as Raman spectroscopy. The current load distribution over the surface of the emitters is investigated and current-voltage characteristics are obtained at different levels of cathode high voltage training, including an assessment of temporal current stability as well as the "orthodox" test for compliance field emission data with the classical cold field emission regime. Sufficiently high levels of emission current above 3 mA have been obtained.

Flexible field emitters based on polyvinyl alcohol– multi-walled carbon nanotube nanocomposite film were fabricated via a simple, cost-effective chemical route. Three cathode configurations — Edge, Loop, and Flat — were investigated for field emission performance. The Flat configuration exhibited superior characteristics, achieving a turn-on field of 2.77 V/μm, a stable emission current of 3 mA at 4 V/μm. These results demonstrate the potential of solution-processed nanocomposite films for large-area flexible electron sources in vacuum nanoelectronic applications.

The study examines the contribution of the measurement system's noise characteristics to the formation of the SK diagram. The experimental system is a multichannel computerized setup for studying field cathodes, which scans the samples in a fast 'continuous wave' mode and is equipped with a software tool for recording and reproducing experimental results in emulation mode. The structure of fluctuations in the voltage applied to the cathode has been studied, and the influence of these fluctuations on the spread of effective emission parameters and the shape of the SK-diagram has been modeled. It has been shown that the experimental spread is an order of magnitude larger than the spread associated with the influence of noise.

The work presents and implements a method for processing experimental field emission data that differs from the classical regression analysis approach. The effective parameters (field enhancement factor and emission area) for a cathode based on ZnO semiconductor nanocrystals are estimated using the theoretical dependence of current density on the surface field, which was constructed by simultaneously solving the Stratton field emission equation and the Poisson differential equation. The general trend line method was used to approximate the data without an analytical equation.

Field electron emission (FE) is an effect that initiates several discharge processes such as surface flashover or vacuum breakdown. Therefore, it is vital to accurately predict field emission current to prevent or maintain these processes. Most field emission theories, as well as most of the scientific literature on field emission, employ the approximation of a smooth planar metal-like emitter (SPME) to predict emission current density and emission current, wherein the emitter is represented as a planar surface with uniform characteristic field enhancement and local work function (WF). In this work, we propose an extension of this framework — the approximation of a smooth-shaped metal-like emitter that accounts for emitter geometry and the spatial distributions of local electrostatic field and local WF in calculating emission current density and emission current. Using the proposed approximation, field emission properties of a hemisphere-on-cylindrical-post tip with several WF distributions across its hemispherical apex, namely, uniform, radially increasing, and radially decreasing, were evaluated. The influence of variations in the local distributions of these parameters on the total emission current was assessed.

Field emission current - applied field curves were obtained in a computer simulated emitter, taking into account different distributions of the work function over its surface. We aim to quantify the variation in the applied field necessary to generate 1 microampere.

The methods for extracting the main emission parameters are compared when processing the current-voltage characteristics of large-area field emitters made of semiconductor materials. The field emission data from multi-tip zinc oxide nanowire emitters coated and uncoated with thin In2O3 films are investigated. The new method of numerical selection of effective field emission parameters for complex high-precision Murphy-Good equation and the Stratton equation is proposed and compared with classical methods.

Field emission properties of plasma treated carbon nanotube/polystyrene field emitter in deuterium gas environment are studied. Varying the duration of treatment difference in threshold fields has been shown. Optimal duration of surface plasma treatment has been found.

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This work explores the prospects for using a blade-type silicon field emitter as a miniature electron source formed on the basis of reproducible CMOS semiconductor technology. The cathode sample was fabricated on a highly doped silicon substrate using contact lithography and deep anisotropic etching. The cathode had the shape of a rectangular bar with a flat top edge inclined relative to its plane at an angle of anisotropic etching. Using a computerized stand for multichannel collection and recording of field emission data in a pulsed high-voltage scanning mode, its current-voltage characteristic was obtained. Based on the numerical simulation of the electric field on the emitter surface in COMSOL Multiphysics, the calculation of the field emission current was carried out within the Forbes-Dean approximation. In the high voltage region, good agreement has been demonstrated between current values obtained from theoretical calculations and experiment. The simulation also revealed the need to improve the blade geometry for further increasing electron emission efficiency.

This paper is devoted to the study of the characteristics of internal waves in the Kara Sea and their interaction with the atmosphere, in particular, their influence on the turbulent momentum and heat fluxes in the surface layer of the atmosphere. The direction and horizontal velocity of propagation of short-period internal waves in the Kara Gates Strait are calculated. Cross spectra of mesoscale fluctuations of water temperature at the sea surface, at depths of 10 and 20 m, and meteorological parameters at a height of 22 m are analyzed. Common spectral maxima at periods characteristic of the trapped internal gravity modes propagating in the thermocline layer and atmospheric gravity modes in the stably stratified layer of the lower troposphere are revealed. A possible mechanism of influence of the observed gravity modes in the thermocline layer on mesoscale fluctuations of meteorological parameters (with periods from 10 min to several hours) and turbulent fluxes of momentum and apparent and latent heat in the surface layer of the atmosphere is proposed.

The paper describes a technique for training multi-tip field cathodes with high voltage, which makes it possible to optimize the emission current on the basis of field projector data. The paper presents an algorithm for obtaining and analyzing experimental data, which allows for controlled training of the cathode surface, and also presents the results of the analysis of experimental data obtained for a promising nanocomposite structure of carbon nanotubes in polystyrene.

This work presents for the first time the possibility of reducing and tuning the work function of field emission cathodes coated with metal oxides by changing the chemical composition of...

One of the critical aspects in advancing high-brightness field emitter devices is determining the conditions under which single-tip emitters should be constructed to optimize their emission area. Recent experiments have explored varying the axis ratio ξ of the cap of a single-tip emitter, ranging from an oblate semi-spheroid to a prolate shape, mounted on a nearly cylindrical conducting body. In this work, we present a strategy, based on high-accuracy computer simulations using the finite element technique, to maximize the emission area of those single-tip emitters. Importantly, our findings indicate that the notional emission area achieves its maximum when the emitter’s cap is adjusted to an oblate semi-spheroid with a characteristic axis ratio ξC≈0.85. We do a comparison of notional emission area as a function of ξ for an ellipsoidal emitter on a post and compare these results from other emitter configurations, which are feasible to fabricate.

The paper presents field observations of internal waves at the Gelendzhik polygon from 14– 23 June 2023. The measurements were taken simultaneously on four moored thermochaines, installed at a depth of approximately 23 m. Currents were recorded, and the water column was vertically profiled with measurements of temperature, conductivity, and dissolved oxygen. Dissolved oxygen was recorded at a depth of 18 metres on one of the thermochains. The most intense short-period trains recorded after the strengthening of the alongshore north-western current are presented. The internal waves of the first and second modes are revealed. The main parameters of the observed internal waves are estimated. It is shown that near-inertial internal waves approaching the coastal zone contain colder and saltier water with reduced oxygen content. As a result, their approach leads to a 10 % drop in water oxygen saturation at the horizon. An example of the effect of short-period internal waves on dissolved oxygen content is presented.

The results of studying the influence of internal gravity waves (IGWs) on the spatiotemporal variability of atmospheric pressure and wind velocity in the lower troposphere using a triangular network of three microbarographs and an antihail acoustic cannon installed in Talin (Armenia) are presented. By coherent analysis of pressure fluctuations measured at different points, IGWs generated by thunderstorm fronts about 5–6 h before the passage of the fronts over the network of microbarographs have been detected. The regularities of changes in phase speeds and propagation directions of IGWs as thunderstorm precursors with time are studied. The possibility of IGW monitoring in the troposphere by measuring temporal fluctuations of the travel time of acoustic pulses along the ray-paths connecting the antihail cannon with spatially separated acoustic receivers has been demonstrated. Vertical profiles of wind velocity fluctuations in certain layers of the lower troposphere up to a height of 800 m have been retrieved from the shapes and travel times of acoustic pulses having a shock front and scattered by anisotropic fluctuations of wind velocity and temperature in the stably stratified lower troposphere. Owing to the high vertical resolution (on the order of 1 m) of the method of pulsed acoustic sounding of the lower troposphere used here, the vertical spectra of anisotropic fluctuations of wind velocity in the range of short vertical scales, from one to tens of meters, are obtained for the first time and theoretically interpreted.