Dual Beam Research Articles

Numerical Study of Sputter Deposited Ultra-Low Loaded Effective Platinum Electrocatalyst Utilization in Proton Exchange Membrane Fuel Cell

High Platinum loading levels in fuel cells may ensure better durability and catalytic activity but increases fuel cells’ cost, thereby hindering large-scale commercialization. The use of non-precious catalysts may seem like a lucrative solution, but they cannot substitute platinum completely. Hence, the focus should also be given to alternate fabrication methods of the catalyst layer that will achieve ultra-low platinum loadings. Some of the methods are modified thin film method, electrodeposition, sputter deposition method, dual ion beam assisted deposition, and electroless deposition. Nano carbons as catalyst support can also be given priority as they aid the catalyst with mechanical properties. Each method is compared, reflecting the inherent advantages and disadvantages. Finally, the sputter deposition method was chosen as the most promising method in the current state of technology and research. A computational fluid dynamics simulation of a fuel cell using the sputter deposition method was performed which showed high power utilization thereby validating the benefits of the method.

Effect of annealing on ion-beam-sputtered hafnium oxide thin films properties

HfO2 films are high laser damage-threshold and low-absorption thin-films that can be utilized for a broad range of optoelectronic and optical applications. In this study, HfO2 thin films were prepared via dual ion beam sputtering followed by annealing in the atmosphere at temperatures ranging from 200 to 700 °C. The optical properties, microstructure, film stress, and absorption loss of the HfO2 films at various annealing temperatures were then systematically characterized. The results revealed that the properties of the films were improved after annealing at temperatures below 500 °C. Specifically, at an optimal annealing temperature of 400 °C, the residual stress of the films was minimized close to zero and the absorption loss was as low as 1 ppm. However, at annealing temperatures reaching 600 °C, the films began to crystallize, leading to the deterioration of their optical properties. Optimizing the process parameters for HfO2 thin film deposition is crucial for developing the next generation of high-performance laser optics.

Holmium doped La2O3 and its Composite with Graphitic Carbon Nitride for the Removal of Atrazine and Chlorpyrifos from Wastewater

Herein, the co-precipitation method was employed for the synthesis of rare earth metal oxide La2O3, Holmium doped La2O3, and its composite with 2D layered material i.e. graphitic carbon nitride (g-C3N4) to study their photocatalytic behavior towards organic pollutants. Pollutants employed to study are pesticides that include atrazine and chlorpyrifos. Structural, spectral, morphological, and elemental analysis were done by XRD, FTIR, SEM, and EDX respectively. Optical bandgap calculations showed the decrease in band edge positions of the bare La2O3 from 5.02eV to 3.39eV by doping of Ho in La2O3 lattice. The photocatalytic degradation efficiency of prepared samples was evaluated using a dual beam UV-Visible spectrophotometer. Experimental investigation showed that the prepared composite i.e. Ho doped La2O3@g-CN had remarkable photodegradation activity of about 60% and 86% towards the atrazine and chlorpyrifos respectively. While the pristine La2O3 showed only 41% and 65% degradation activity and Ho doped La2O3 showed 52% and 75% removal efficiency for atrazine and chlorpyrifos respectively by using 0.03g/100mL of photocatalysts under solar light exposure of about 80min. The enhanced degradation activity of composite (g-C3N4/Ho@La2O3) as compared to its other counter parts is due to its increased surface area and more active sites provided by g-C3N4 for electrons trapping to cause a delay in electron-hole pair recombination rate. The enhanced surface area also played a key role in adsorbing more pollutant molecules for degradation.

Terahertz single/dual beam scanning with tunable field of view by cascaded metasurfaces

Dynamic beam scanning with a dynamically tunable beam number, beam direction, and beam polarization remains a challenge in the terahertz gap, which is urgently needed for terahertz radar, next-generation wireless communication, and imaging applications. Different from programmable metasurfaces with element-level phase control, the beam direction is dynamically controlled by two cascaded all-dielectric metasurfaces during in-plane rotation. For a pair of circularly polarized beams with opposite handedness, the scanning field of view (FOV) can be the same or different according to the independent phase modulation in both layers and for both polarization states. Switchable single-beam and dual-beam scanning is achieved by controlling the incident polarization, which covers the ±60° FOV at 0.291 THz with an angular step of 1° and an average gain of 16.2 dBi. The output beam is quasi-circular polarized with an average ellipticity of 0.83. Single beam scanning along a Fibonacci spiral trajectory and dual beam scanning along symmetric and asymmetric trajectories are experimentally validated. Different beam scanning processes are recorded using a terahertz camera, which show good agreement with the theoretical prediction. The wide field-of-view continuous beam scanning with a switchable number of beams and a flexible FOV may have a significant impact on the development of terahertz radar and terahertz intelligent antennas.

Scattering characteristics of dual counter-propagation high-order circularly symmetric Bessel beam by a multilayer chiral sphere

The interaction between dual counter-propagating high-order circularly symmetric Bessel beams (CSBBs) and multi-layered chiral particles is investigated. Within the framework of generalized Lorenz-Mie theory (GLMT), the distribution characteristics of the superposition of two beams are studied based on the vector superposition theorem. The near-field, internal field, and far-field radar cross section (RCS) of the dual-layered chiral sphere illuminated by dual CSBBs are obtained according to the boundary conditions. By comparing the results of RCS with those from the references for two cases: first, when CSBBs degenerate into plane waves incident on multi-layered chiral sphere, and second, when Bessel beams illuminate isotropic multi-layer sphere degenerated by chiral multi-layered sphere, the effectiveness of the principle and program exhibited here is confirmed. The impact of various parameters on the distribution of the superposed field, the near-field, internal field, and far-field RCS of the particles are analyzed in detail, such as the order, half-cone angle, incidence angle, and polarization angle. The research results in this paper provide theoretical assistance for understanding the interaction between dual CSBBs and non-uniform chiral multi-layered particles and have important value in realizing optical manipulation of complex chiral layered particles.

Temperature-controlled synthesis of novel boron nanofibers by laser ablation technique

The synthesis of boron nanofibers (BNFs) at different temperatures using the double-pulsed laser ablation (DPLA) technique were reported. Q-switched Nd: YAG laser with 532 and 1064 nm dual beam wavelengths of laser used to ablate a solid boron target. A vapor–solid process at a furnace temperature and pressure supported boron 'nanofibers' growth with the active metal catalysts of 1 % Ni and 1 % Co in a quartz tube furnace in flowing argon (Ar) gas. The crystalline phase purity of the synthesized BNFs at 950, 1050, and 1150 °C were determined by X-ray diffraction (XRD), and the results from XRD confirm that each BNF is preferentially grown in the c-axis (100) direction of alpha boron (α-B). Electron microscopy revealed that each BNF exhibit a length of 1–5 μm and a diameter width of 5–100 nm, while the elemental chemical compositional nature of the BNFs is identified from energy dispersive X–ray spectroscopy (EDX). Image analysis shows the average diameter of each BNF synthesized to be 23.10, 19.13, and 16.09 nm. The lattice distance of each BNF is found to be 0.40, 0.39, and 0.38 nm, respectively. Fingerprint Raman spectroscopy revealed the fundamental vibrational modes of BNFs at Eg and A1g.

High-throughput fluorescence lifetime imaging flow cytometry

Flow cytometry is a vital tool in biomedical research and laboratory medicine. However, its accuracy is often compromised by undesired fluctuations in fluorescence intensity. While fluorescence lifetime imaging microscopy (FLIM) bypasses this challenge as fluorescence lifetime remains unaffected by such fluctuations, the full integration of FLIM into flow cytometry has yet to be demonstrated due to speed limitations. Here we overcome the speed limitations in FLIM, thereby enabling high-throughput FLIM flow cytometry at a high rate of over 10,000 cells per second. This is made possible by using dual intensity-modulated continuous-wave beam arrays with complementary modulation frequency pairs for fluorophore excitation and acquiring fluorescence lifetime images of rapidly flowing cells. Moreover, our FLIM system distinguishes subpopulations in male rat glioma and captures dynamic changes in the cell nucleus induced by an anti-cancer drug. FLIM flow cytometry significantly enhances cellular analysis capabilities, providing detailed insights into cellular functions, interactions, and environments.

Measuring Transverse Relaxation with a Single-Beam 894 nm VCSEL for Cs-Xe NMR Gyroscope Miniaturization.

The spin-exchange-pumped nuclear magnetic resonance gyroscope (NMRG) is a pivotal tool in quantum navigation. The transverse relaxation of atoms critically impacts the NMRG's performance parameters and is essential for judging normal operation. Conventional methods for measuring transverse relaxation typically use dual beams, which involves complex optical path and frequency stabilization systems, thereby complicating miniaturization and integration. This paper proposes a method to construct a 133Cs parametric resonance magnetometer using a single-beam vertical-cavity surface-emitting laser (VCSEL) to measure the transverse relaxation of 129Xe and 131Xe. Based on this method, the volume of the gyroscope probe is significantly reduced to 50 cm3. Experimental results demonstrate that the constructed Cs-Xe NMRG can achieve a transverse relaxation time (T2) of 8.1 s under static conditions. Within the cell temperature range of 70 °C to 110 °C, T2 decreases with increasing temperature, while the signal amplitude inversely increases. The research lays the foundation for continuous measurement operations of miniaturized NMRGs.

Dual beam optical coherence tomography angiography for decoupling axial velocity gradient

Axial velocity gradient (AVG) in the optical coherence tomography angiography (OCTA) signal affects measurement accuracy when the flow is not perpendicular to the scanning beam. We developed a dual beam OCTA method to decouple the contribution of AVG from the decorrelation signal. Decoupling is first verified by phantom experiments which reduces measurement uncertainty from 1.5 to 0.7% (standard deviation). We also tested the method in human skin in vivo and the results indicate that the contribution of AVG to decorrelation signal is reduced.

Spoof surface plasmon Polaritons dual beam scanning antenna for 5G application

Dual beam scanning (DBS) antenna exited by two different spoof surface plasmon polaritons (SSPPs) transmission lines is proposed in this paper. The antenna is constructed by placing three rows of circular patches on both sides of two different planar SSPPs waveguide. These patches convert the SSPP guided waves into radiating waves. This simple single-layer antenna is characterized by dual without need to use switches or other complex configurations. It is designed to support application of several 5G sub-6 GHz bands (3.5 (n78) GHz, 3.7 (n77) GHz, and 4.5 (n79) GHz). The proposed antenna realizes the dual beam scanning by controlling the dispersion properties and field confinement along two different SSPPs transmission lines, based on different propagation constant. Numerical simulations are carried out by CST Microwave Studio and Ansys HFSS. These numerical simulations are verified by experimental results over the operating frequency band from 1 GHz to 6 GHz.

A Wideband Millimeter-Wave Dual-Beam Dielectric Resonator Antenna with Substrate Integration Capability.

A wideband dual-beam dielectric resonator antenna (DRA) with substrate integration capability was proposed for millimeter-wave (mm-wave) applications. The four rows of air vias along the x-direction and two extended rectangular patches could shift the undesirable radiation mode upward and move the conical-beam radiation mode downward, respectively. Thus, the TE211 mode and the TE411 mode of the patch-loaded perforated rectangular substrate integrated dielectric resonator (SIDR) supporting the dual-beam radiation can be retained in the operating band, and their radiation can be improved by the air vias along the y-direction. The T-shaped line coupled dual-slot structure could excite the above two modes, and a dual-slot mode supporting dual-beam radiation could also work. Then, a wideband DRA with a stable dual-beam radiation angle can be achieved, and its impedance matching can be improved by two air slots on two sides. Compared with the state-of-the-art dual-beam antennas, the proposed antenna shows a wider bandwidth, a higher radiation efficiency, and the substrate integration capability of DRA, making it more suitable for mm-wave applications. For demonstration, a 1 × 4 array was designed with the 10 dB impedance matching bandwidth of 41.2% and the directions of the dual beams between ±30° and ±35°.

Dual band beam steering antenna using branch line coupler network for higher band applications

Abstract A beam-steering fed array antenna has been proposed for radar and mm-Wave applications operating from 22.6 to 26.89 GHz and 30–45 GHz with B.W % of 17.34 % and 40 % respectively having size of 12.11 × 25.58 × 0.8 mm3 (0.96λo × 2.01λo × 0.06λo). For radar, this antenna covers 24.15 GHz as police radar, 24.25–25.25 GHz & 31.8–33.4 GHz as navigation radar, and 33.4–36 GHz as high-resolution radar for airport surveillance. This antenna also covers mm-wave bands for different countries (Brazil-40 GHz, China- 34–42.5 GHz, Mexico- 33 GHz and 37 GHz, and USA- 24 GHz, 37 & 39 GHz). At initial stage, a monopole antenna with DGS has been designed with an operating band of 20.2–31.2 GHz and 36.6–42.2 GHz. Proposed antenna shifts the beam pattern at 90° with each other after exciting each port in alternative order with a scanning angle of ±45°, ±75° & ±180°. Peak gain for 1st band ranges from 7.1 to 9 dBi and for the 2nd band ranges from 8.8 to 10.2 dBi and has a radiation efficiency of 88 %. Other diversity parameters such as ECC, DG, MEG, and isolation get analysed to observe the coupling effects. Design, development, and analysis of all antenna parameters is done by using HFSS 19 platform.

Tailoring the Lithium Concentration in Thin Lithium Ferrite Films Obtained by Dual Ion Beam Sputtering.

Thin films of lithium spinel ferrite, LiFe5O8, have attracted much scientific attention because of their potential for efficient excitation, the manipulation and propagation of spin currents due to their insulating character, high-saturation magnetization, and Curie temperature, as well as their ultra-low damping value. In addition, LiFe5O8 is currently one of the most interesting materials in terms of developing spintronic devices based on the ionic control of magnetism, for which it is crucial to control the lithium's atomic content. In this work, we demonstrate that dual ion beam sputtering is a suitable technique to tailor the lithium content of thin films of lithium ferrite (LFO) by using the different energies of the assisting ion beam formed by Ar+ and O2+ ions during the growth process. Without assistance, a disordered rock-salt LFO phase (i.e., LiFeO2) can be identified as the principal phase. Under beam assistance, highly out-of-plane-oriented (111) thin LFO films have been obtained on (0001) Al2O3 substrates with a disordered spinel structure as the main phase and with lithium concentrations higher and lower than the stoichiometric spinel phase, i.e., LiFe5O8. After post-annealing of the films at 1025 K, a highly ordered ferromagnetic spinel LFO phase was found when the lithium concentration was higher than the stoichiometric value. With lower lithium contents, the antiferromagnetic hematite (α-Fe2O3) phase emerged and coexisted in films with the ferromagnetic LixFe6-xO8. These results open up the possibility of controlling the properties of thin lithium ferrite-based films to enable their use in advanced spintronic devices.

Portable 5-DOF measurement system using a parallel beam generation method for linear axis detection

Geometric error detection is crucial for evaluating the accuracy of the linear axis. However, the practicality of traditional dual-beam detection systems is limited by the parallelism of beams. This study proposes a portable 5-DOF measurement system using a novel parallel beam generation method. Two orthogonal corner cube retroreflectors (CCRs) and a beam splitter (BS) are utilized to achieve two measuring beams with excellent parallelism, which is determined solely by the CCR. The theoretical parallelism of beams is analyzed and experimentally verified. Two position sensitive detectors (PSDs) and one autocollimator are used to measure two straightness errors and three angular errors, and the detection deviations are modelled and compensated. The experiment proves that dual beam that are generated on the basis of the above structure could achieve a parallelism of 5.9′′ without careful adjustment. The designed 5-DOF measurement system has a straightness measurement range of ± 400 µm and an angle measurement range of ± 300′′. The repeatability of the system is 2.20 µm for straightness errors, 1.58′′ for yaw error, 1.82′′ for pitch error and 5.04′′ for roll error detection. The designed 5-DOF measurement system has the advantages of a simple structure and stable accuracy and is very practical in measuring the geometric errors of machine tools.

Design of a low-profile bi-directional radiated Fabry-Perot cavity antenna with independent forward and backward radiation based on metasurface technique

This paper introduces a novel Fabry-Perot cavity (FPC) antenna design based on metasurface technique to achieve bi-directional radiation with independent forward and backward beam control capability and a low-profile configuration. Two pieces of partially reflective metasurface (PRMS) based on receiver-transmitter architecture with independent control of transmission and reflection phases are designed to serve as the upper and lower layers of the FPC antenna, respectively. By manipulating the transmission phase distribution of the two pieces of PRMS, designable independent multi-beam bi-directional radiation patterns can be achieved. For validation, two FPC antennas based on the proposed configuration are designed with different bi-directional radiation patterns. Proved by simulated results, Antenna 1 can achieve forward dual-beam and backward single-beam radiation simultaneously with a return loss of less than -10 dB at 10.4 GHz. The two beams of forward radiation point in the -45° and 35° directions, respectively, with gains of 7.42 dBi and 7.70 dBi. The gain of the single beam of backward radiation is 10.82 dBi. Antenna 2 can achieve a four-beam radiation pattern with both forward and backward dual beams. The beam directions of the four beams are -153°, -44°, 37°, and 146°, respectively. The gains in each direction are 5.45 dBi, 6.63 dBi, 5.97 dBi, and 5.22 dBi, respectively. The overall profile is 23.72 mm (0.81 λ) for both antennas. The prototype of Antenna 1 is fabricated and measured. The results are in good agreement with the simulated counterparts, which demonstrates the feasibility of the proposed design methodology.

Finite Element Modeling of Ring and Gaussian Dual Laser Heat Sources for Aluminum Butt Welding

Aluminum alloys have been used extensively for automotive industries for the structural applications with their high specific strength and corrosion resistance. In order to use aluminum alloys for automotive components, laser welding has been used due to the advantage of being capable to weld thick products due to its deep penetration depth. In this regard, a dual laser heat source combining an outer ring laser beam with a centrally focused Gaussian laser beam was proposed to compensate for insufficient melting caused by laser reflection of aluminum alloy. The purpose of this study is to develop a simulation model that can consider heat input from the dual laser beams individually, for analyzing melting and heat distribution behavior during the laser welding. Two different heat source models were proposed. One model used 3D Gaussian distribution of heat input for the centrally focused laser while the other model utilized Gaussian cylinder heat input. The proposed heat input models were implemented by finite element analyses, and the results were compared with aluminum butt welding experiments. It was shown that Gaussian cylinder heat input for the centrally focused laser beam reproduced much better the experimentally observed melting behavior in comparison to the 3D Gaussian distribution.

Laser sintering of polyamide 12 with limited thermal degradation

The paper presents, for the first time, the results of PA12 polyamide sintering using the original method of Dual Beam Laser Sintering of polymers (DBLS). The DBLS method, which is a modification of the standard polymer Laser Sintering (pLS) approach, allows to reduce the thermal degradation of the polymer by using selective (in terms of powder volume and process time) heating the material with laser radiation. The paper presents both the properties of sintered parts and the analysis of the degree of thermal degradation of post-process powders. Examination of the sintered parts included X-ray computed tomography (XCT) to visualize and analyze their porosity and a tensile test. Post-process powders were evaluated by Gel Permeation Chromatography (GPC), Melt Flow Rate (MFR), Dry Laser Diffraction Spectroscopy (DLD) and Powder Rheometer (FT4). The analysis of the result of PA12 sintering with the DBLS method was carried out in comparison with the classic pLS approach. As it has been shown, the DBLS approach allows to obtain comparable results for sintered parts compared to the pLS method. What is particularly important, it was shown that the post-process powder in the DBLS method has almost unchanged properties - the change in molecular weight and viscosity is at the level of the measurement error. Reducing thermal degradation is especially important in order to obtain continuous circulation of the powder in the manufacturing process.

The impact of ring-shaped laser beam on dissimilar welding of Al-Cu thin sheets for battery tab-to-busbar connection: Microstructural, mechanical and electrical characteristics

Al-Cu dissimilar laser welding has gained substantial attention in the electric vehicle battery manufacturing, while challenged by the formation of brittle Al-Cu intermetallic compounds (IMCs). This study investigated the impact of beam shaping technology on the characteristics of Al-Cu dissimilar laser welds by using a coaxial core and ring dual beam laser system. The investigation assessed multi-level weld characteristics including weld geometry, IMC formation, mechanical and electrical properties. Results showed that the dual laser beam can effectively avoid imperfections observed with single beam, such as full penetration related to core-only beam and surface discontinuity defects associated with ring-only beam, respectively. For the core-only weld, extensive upward migration of Cu promoted the formation of brittle CuAl2 and Cu9Al4/Cu3Al2, leading to a considerable reduction in joint strength and a sharp increase in the electrical resistance. For the ring-only weld, the insufficient bonding area between Al and Cu sheet, leads to a significant degradation of joint strength, although a minimal electrical resistance was identified. An optimized power splitting was determined at 40% for the core beam and 60% for the ring beam, which allows the minimal formation of Al-Cu IMCs and consequently, the improved mechanical strength and reduced electrical resistance.

Effect of rapid thermal annealing on DC performance of Mg0.30Zn0.70O/Cd0.15Zn0.85O MOSHFET

This study focuses on a cost-effective method for fabrication of a metal oxide semiconductor-heterostructure field effect transistor (MOSHFET) based on MgZnO/CdZnO (MCO) using dual ion beam sputtering (DIBS), in contrast to the more expensive epitaxial growth system. The MOSHFETs developed in this research exhibit notable characteristics, such as a substantial two-dimensional electron gas (2DEG) transconductance (∼2.6 mS), a high ION/IOFF response ratio in the order of 108, and minimal gate leakage current. Furthermore, we explore the impact of rapid thermal annealing (RTA) on the drain current at various temperatures (600 °C and 800 °C). The results indicate a fourfold improvement in drain current compared to unannealed conditions, primarily attributed to reduced contact resistance and no degradation in term of MgZnO/CdZnO structure. Additionally, an analysis of post-RTA treatment under a nitrogen (N2) atmosphere on gate leakage current is presented. The investigation spans temperatures ranging from 400 °C to 800 °C, revealing that above 600 °C (gate leakage at 400 °C–600 °C is around ∼10−9 A), gate leakage in HFET is augmented by one order of magnitude (∼10−8 A) due to a phase change in the dielectric. These findings underscore the feasibility of DIBS-grown MCO MOSHFETs as an economical solution for the mass production of switching devices and sensors.

Differences in coupling between nuclear and electronic energy losses in UO2 with irradiation temperature: An in situ TEM study

To investigate the coupling between nuclear and electronic energy losses in UO2, we irradiated thin foils with 0.39 MeV Xe and/or 6 MeV Si ions at 93 K using single or simultaneous dual beam ion irradiations. The evolution of perfect dislocation loops was characterized by in situ transmission electron microscopy (TEM). Additional ex situ TEM characterizations at room temperature revealed for the first time in UO2 the presence of faulted Frank loops too small to be measured during in situ experiments and conventional bright field kinematical imaging conditions.For the single Xe irradiation, which favor dominant ballistic energy losses, we observed a continuous nucleation of small perfect dislocation loops, which increase in size for our last fluences by growing through mainly coalescence effect. Both the single Si and dual Xe & Si irradiations showed a coupling between nuclear and electronic energy losses, resulting in a significant loop density increase and a tangled line network formation, respectively. These phenomena occur at lower dpa levels, compared to the single Xe irradiation, likely resulting from the thermal spike effect of Si ions. The present results were compared to our previous work at 293 K to investigate the role of irradiation temperature on the energy losses coupling. For the Xe irradiation, the density increases and the loops are smaller at 93 K compared to 293 K, resulting from the uranium interstitials mobility being prevented or allowed. For the Si irradiation, the dislocation evolution kinetics are similar at both temperatures. The electronic excitations effect seems greater than the irradiation temperature effect in this temperature range. For the Xe & Si irradiation, the loop kinetics change resulting in a tangled line network formation is faster and thus the loop transformation into lines occurs at lower dpa levels at 93 K compared to 293 K. It appears that the irradiation temperature affecting the mobility of some small point defects reduces the electronic excitation effect in this case.