Numerical Analysis of Leakage Field Modulation for a Novel Direct Overwrite Medium

We have developed a combined Raman scattering spectroscopy and disk property measurement system to evaluate crystallinity of SRR functional layer inside the rotaed optical disk. The CNR and Raman scattering spectrum can be measured simultaneously from Sb functional layer. Stokes and anti-stokes peak intensities of the spectrum were dependent and independent on the laser power. We have discussed that it is closely related to the SRR phenomenoin.

The simplified model of a small transformer for simulation of space-distribution of leakage field is described. The authors suggest for calculation a well-known and perspicuous finite difference method with numerical procedures based on Fast Fourier Transform worked out in the National Center for Atmospheric Research Colorado USA. The simpli-field model may be used for numerical calculations of transformer system in which the eddy-currents in constructional elements (e.g. in the transformer tank), are ommitted.

A simple method for the evaluation of materials suitable for the fabrication of field emission vacuum microelectronic devices is presented. Since there can be a wide range of electron and ion interactions with the device, it is important to be able to quickly assess if a material may have a particular adverse effect on emission performance under operational conditions. The technique is based on the sensitivity of a large field emitter array to the outgassing or desorption of gas species from thin films under electron beam excitation. We found that Mo field emitter arrays degraded rapidly with stainless steel anodes coated with various oxide materials. The extent of degradation was found to be the most rapid with SiO2, Si3N4, and MoO3 thin films. Stainless steel anodes with Mo and Nb thin films show a faster degradation rate than stainless steel anodes, most likely because of native oxides grown during processing and handling. The emission behavior in the presence of Ir, Pd, Al, Zn, and Ti metal films and barrier materials like C and TaN is similar to stainless steel reference data. We find that once the oxide films are covered with barrier layers like C and TaN, emission decay rates approach the values obtained with stainless steel reference anodes. The observed emission current degradation is consistent with a model based on the liberation of oxygen from the surface of electron beam bombarded materials. Using controlled oxygen exposure experiments, we have determined the equivalent local oxygen pressures in the presence of various thin films. We found that with thin films of Nb, ZrO2, Ta2O5, MgO, Nb2O5, and Al2O3, the emission degradation is akin to having a local O2 partial pressure in the 1×10−7–1×10−6 Torr range and with Mo, MoO3, Si3N4, and SiO2, this is equivalent to having local O2 pressures of 1×10−5 Torr.

Atomic layer etching (ALE) can result from sequential, self-limiting thermal reactions. The reactions during thermal ALE are defined by fluorination followed by ligand exchange using metal precursors. The metal precursors introduce various ligands that may transfer during ligand exchange. If the transferred ligands produce stable and volatile metal products, then the metal products may leave the surface and produce etching. In this work, selectivity in thermal ALE was examined by exploring tin(II) acetylacetonate (Sn(acac)2), trimethylaluminum (TMA), dimethylaluminum chloride (DMAC), and SiCl4 as the metal precursors. These metal precursors provide acac, methyl, and chloride ligands for ligand exchange. HF-pyridine was employed as the fluorination reagent. Spectroscopic ellipsometry was used to measure the etch rates of Al2O3, HfO2, ZrO2, SiO2, Si3N4, and TiN thin films on silicon wafers. The spectroscopic ellipsometry measurements revealed that HfO2 was etched by all of the metal precursors. Al2O3 was et...

In this paper we are going to present FEM calculations applied for laser bending of silicon microstructures and compare them with our experimental results. According to the mechanisms in plastic deformation of metals with laser radiation we performed calculations to find out, if there are similar mechanisms in forming of silicon. To model the laser heating up mechanism we have to take into account several physical effects like heat radiation or reflection of silicon for the used laser radiation. To transform the laser bending process into a FE model the boundary conditions include compromises and simplifications of the geometry and the energy input. In our calculations we modelled the laser beam as a moving heat source in order to get information about the temperature distribution, the temperature gradient and the heat flow in dependence on the position on the sample and the time. The calculated essentially higher temperatures at the edges of the structure compared to the middle of the structure, exceeding the melting point there, are in very good agreement to the melting areas observed at the edges in the experi-ments. After a number of consecutive scans we reach a balanced temperature field moving with the laser beam across the surface. The calculations revealed that there is a steep temperature gradient in the depth of the structure indicating a similar temperature gradient mechanism observed in forming of metals with laser radiation. Additionally we carried out temperature field calculations to determine the influence of the process parameters like the laser power, the velocity of the heat source, the material thickness or the position of laser treatment on the temperature field generated in the material. The results of the calculations are in very good agreement with our experiments. Next time stress field calculations are intended. At the moment there are not enough data on the plastic behaviour of silicon available to the authors in order to get reliable results.

Application of a flexible memristor in self-color electronics and its depth mechanism analysis

To study the surface morphology of laser cladding, Workbench simulated the influence of laser power and scanning speed on the width and height of the cladding layer numerically, as well as the temperature field change and residual stress distribution of the cladding layer. The simulation results reveal that the melting height and width of the cladding layer are inversely proportional to the scanning speed. When the scanning speed is from V = 3 mm/s to V = 5 mm/s, the Al cladding layer’s melting width and melting height are reduced by 15.59% and 20.8%, respectively. A positive correlation exists between the melting height and width of the cladding layer and the laser power. When the laser power changes from P = 23 w to P = 27 w, the welding width and height of the A1 cladding layer increase by 6.55% and 55.56%, respectively. The melting height and width of the second cladding layer are generally higher than those of the bottom cladding layer. The pre-experiment screening process parameters ranges are laser power P (23 w–27 w) and scanning speed (3 mm/s–8 mm/s). Based on the Minitab response surface central composite method, the most notable influence on the melting height and width is revealed to be the powder-feeding rate and laser power, respectively. The response surface analysis method establishes the regression prediction models of melting width and height. The predicted value of melting width was 95.68%, and the predicted value of melting height was 82.26%. The results show that the values of cladding width and height are within the 95% prediction interval, proving that the regression model is correct.

A microvortex was discovered in liquid films when subjected to the combined action of a focused laser beam and a high-frequency electric field. The laser beam was perpendicular to both the surface of the liquid film and the direction of the electric field. The size of this opto-electrostatic microvortex (OEMV) in various liquids (water, ethanol, acetone, nitrobenzene) varied with the experimental conditions, but stayed in the 10-/spl mu/m range. The velocity of the liquid flow in the vortex could be controlled by the intensity and frequency of the electric field (5.0/spl times/10/sup 4/ to 0.8/spl times/10/sup 6/ V/m, 2/spl times/10/sup 4/ to 1/spl times/10/sup 6/ Hz), by the laser power (0.01 to 2 W) and by the laser power density in the focal point. No microvortex was observed in benzene and chloroform. As an application of this phenomenon, single DNA molecules could be transported along the OEMV.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Transient characteristics of a solid oxide electrolysis cell under different voltage ramps: Transport phenomena behind overshoots

With high diffractive efficiency, Continuous Relief Diffractive Optical Elements (CR-DOE) can be used to eliminate chromatic aberration, partial aberration and simplify optical system. The technology for CR-DOE with Laser Direct Writing method has advantages of simple process, short period and low cost. The paper studied on the characterization method of laser power for the technology. The principle of mask fabrication of CR-DOE by Laser Direct Writing is described in the paper. The relations between microstructure depth and laser power, exposing position radius and laser power were studied. The results showed that microstructure depth changes in direct ratio to laser power and laser power should change in direct to exposing position radius while several same depth microstructures were fabricated at different radius. At the end, the paper gave the charactering method and also fabricated the mask of a kind of centrosymmetric continuous relief diffractive focus lens with the method.

Exchange coupling and switching fields of RE—TM double and triple layer stacks for direct overwrite

Septum magnets are used in the injection and extraction section of the 3 GeV rapid cycling synchrotron (RCS) of J-PARC (Japan Proton Accelerator Research Complex). The RCS needs seven septum magnets, two for the injection line, two for the beam dump line and three for the extraction line, respectively. These septa require a large aperture for low-loss operation with high intensity beams, and high durability for minimizing maintenance after high activation. For insuring mechanical stability the septum magnets have been designed to work DC. The septa magnets work outside a vacuum, thus eliminating any trouble due to the leakage of cooling water into the vacuum system. We have been designing them by using the three dimensional magnet static field calculation code, TOSCA. This paper describes the flatness of the magnetic field in the gap and reduction of the leakage field of the septum magnets in the RCS

Light is a powerful non-invasive tool that can be exploited to probe highly scattering media like biological tissues for different purposes, from the detection of brain activity to the characterization of cancer lesions. In the last decade, timedomain diffuse optics (TDDO) systems demonstrated improved sensitivity when using time-gated acquisition chains and short source-detector separations (ρ), both theoretically and experimentally. However, the sensitivity to localized absorption changes buried inside a diffusive medium strongly depends on many parameters such as: SDS, laser power, delay and width of the gating window, absorption and scattering properties of the medium, instrument response function (IRF) shape, etc. In particular, relevant effects due to slow tails in the IRF were noticed, with detrimental effects on performances. We present simulated experimental results based on the diffusion approximation of the Radiative Transfer Equation and the perturbation theory subjected to the Born approximation. To quantify the system sensitivity to deep (few cm) and localized absorption perturbations, we exploited contrast and contrast-to-noise ratio (CNR), which are internationally agreed on standardized figures of merit. The purpose of this study is to determine which parameters have the greatest impact on these figures of merit, thus also providing a range of best operative conditions. The study is composed by two main stages: the former is a comparison between simulations and measurements on tissue-mimicking phantom, while the latter is a broad simulation study in which all relevant parameters are tuned to determine optimal measurement conditions. This study essentially demonstrates that under the influence of the slow tails in the IRF, the use of a small SDS no longer corresponds to optimal contrast and CNR. This work sets the ground for future studies with next-generation of TDDO components, presently under development, providing useful hints on relevant features to which one should take care when designing TDDO components.

There exists a clear physical motivation for theoretical studies of the vacuum instability related to the production of electron-positron pairs from a vacuum due to strong external electric fields. Various nonperturbative (with respect to the external fields) calculation methods were developed. Some of these methods are based on possible exact solutions of the Dirac equation. Unfortunately, there are only few cases when such solutions are known. Recently, an approximate but still nonperturbative approach to treat the vacuum instability caused by slowly varying $t$-electric potential steps (time dependent external fields that vanish as $|t|\rightarrow\infty$), which does not depend on the existence of the corresponding exact solutions, was formulated in Ref. [S. P. Gavrilov, D. M. Gitman, Phys. Rev. D \textbf{95}, 076013 (2017)]. Here, we present an approximate calculation method to treat nonperturbatively the vacuum instability in arbitrary weakly inhomogeneous $x$-electric potential steps (time-independent electric fields of a constant direction that are concentrated in restricted space areas, which means that the fields vanish as $|x|\rightarrow\infty$) in the absence of the corresponding exact solutions. Defining the weakly inhomogeneous regime in general terms, we demonstrate the universal character of the vacuum instability. This universality is associated with a large density of states excited from the vacuum by the electric field. Such a density appears in our approach as a large parameter. We derive universal representations for the total number and current density of the created particles. Relations of these representations with a locally constant field approximation for Schwinger's effective action are found.

Reconfigurable intelligent surfaces (RISs) are key enabling technologies for next-generation wireless telecommunication systems, offering dynamic control over electromagnetic (EM) wave propagation. However, most existing RIS demonstrations rely on conventional electronic or metallic platforms, raising concerns about resource availability, recyclability, and environmental sustainability. In this study, hybrid nanostructured RIS prototypes (Prototypes I-III) were designed and fabricated using sustainable, wood-derived materials, namely, cellulose nanofibers (CNFs), suberin, and biocarbon, in combination with thermoresponsive vanadium dioxide (VO2) nanoparticles. The EM performance of these RIS architectures was first optimized through full-wave simulations and then validated experimentally by the cast-layer deposition of VO2/CNF-suberin functional layers onto printed circuit board (PCB) substrates. Among the tested designs, Prototype I, comprising a functional layer of 95 wt % VO2, 2.5 wt % nonderivatized CNF, and 2.5 wt % suberin, exhibited the most pronounced thermal response, showing resonance frequency shifts of up to 19 MHz at a 5 GHz center frequency and phase shifts of 83° with temperature variation. Prototype II, containing cationic CNFs, demonstrated improved mechanical stability but reduced electrical continuity due to microstructural cracking, whereas Prototype III, modified with biocarbon, displayed diminished conductivity arising from its lower VO2 content. Degree of linear polarization (DOLP) analysis revealed early stage phase transitions that occurred prior to complete conductive pathway formation. Overall, the hybrid RIS architectures developed from VO2 and wood-derived materials through a sustainable processing route exhibited highly tunable, temperature-triggered EM modulation, with sensitivity ranging from low to high, depending on the material composition and assembly configuration.