Physica Scripta

Droplets in vacuum arc can have significant influence on the plasma characteristics and be harmful to devices such as vacuum ion sources and vacuum interrupters. Especially for the droplets with a diameter of the order of magnitude of 100 μm, the plasma parameters can be significantly affected by the ablation cloud. However, this physical mechanism is still unclear due to the lack of self-consistent theoretical research. This study established a self-consistent model to simulate the interaction between droplets and vacuum arc plasma. Dynamic meshing is used to study droplet movement. The simulation results revealed that the ablation cloud of the droplet with a diameter of the order of magnitude of 100 μm can considerably affect vacuum arc parameters. An increase in the droplet temperature increases the droplet vapor density, which increases friction between the ablation cloud and the plasma from the cathode side. Therefore, the deceleration and temperature rise of the droplet decrease. With the increase of the initial droplet diameter, the ablation cloud area increases, which decreases the electron temperature. However, the droplet temperature and droplet velocity are not proportional to the droplet diameter, which indicates the critical role of ablation cloud.

In this paper, by using first principles, we conduct a detailed investigation into structural stability, charge distribution, work function and dipole moment of g-GaN (graphene-like GaN)/Al_0.5Ga_0.5N 2D/3D heterojunction under Cs, Cs/O and Cs/NF₃ activation methods. When Cs coverage is 0.75 monolayer (ML), the band structure, density of states, absorption coefficient and reflectivity of heterojunction are also discussed. Our results indicate that adsorption energies of Cs activated heterojunctions are negative and magnify with higher Cs coverage, leading to a reduction in structural stability. Under high Cs coverage, the addition of O and NF₃ enhance stability of activated heterojunctions. The interaction of Cs with heterojunction surface forms dipole 1, and the interaction with O/NF₃ forms dipole 2. The influences between two dipole moments can additionally reduce surface potential barrier and work function. And the most favorable ratio of Cs to O and Cs to NF₃ is 3:1. After activation, new energy levels are introduced into band structure, primarily attributed to orbital hybridization of s- and p-electron state of activator. Optical property curve show that optical performance of heterojunction can be improved by surface activation, and addition of O and NF₃ will further improve optical absorption of heterojunction.

The recently predicted two-dimensional material C₃Al has a graphene-like lattice structure, but the presence of Al atoms leads to a variety of edge morphologies when it is one-dimensionally clipped. In this paper, the electron transport properties of C₃Al nanoribbons are investigated by first-principles calculations. The results show that they are strongly edge-dependent, being a semiconductor when there are two Al terminal edges, otherwise behaving as metals. Based on this, C₃Al heterojunction devices with different edge morphologies are constructed, in which the 3CAl-NCC and 3CAl-NCAl devices show significant negative differential resistance effects with peak-to-valley ratios up to 2.3 × 10⁴, but such effects diminish with the widening of NCAl, mainly due to the increase of the interfacial spatial barriers suppressing the conductive channel generated by the edge state. The 3CAl-NCAl heterojunction also displays a remarkable rectification effect with a rectification ratio as high as about 1.6 × 10³. The rich electronic properties bode well for their promising applications in nanodevices.

The study investigates the manipulation of the magnetic anisotropy in a thick (1 μm) Ni₉₀Fe₁₀ layer electrodeposited on a ferroelectric BaTiO₃(001) substrate, using a combination of Magneto-optical Kerr Effect, Photoemission Electron Microscopy with x-ray circular magnetic dichroism and x-ray diffraction. In the as-grown state, the system shows weak perpendicular magnetic anisotropy and characteristic stripe domains. Upon out-of-plane electrical poling of the BaTiO₃ substrate, the magnetic anisotropy switches to in-plane with a strong uniaxial behavior. The perpendicular magnetic anisotropy can be recovered by mild thermal annealing above the BaTiO₃ tetragonal to cubic phase transition and can be cycled by repeated electrical poling/thermal annealing. This method opens the path to a reversible control of the magnetic anisotropy in hybrid lead-free magnetoelectric Ni₉₀Fe₁₀/BaTiO₃ heterostructures from perpendicular to in-plane.

In this research, we studied the ultrafast dynamics and phase transition of VO₂ films with different thicknesses. Using transient absorption spectroscopy, the two VO₂ films with thicknesses of 59.5 and 148 nm showed broadband excited state absorption from 450–750 nm, and the maximum absorption peak was at ∼450 nm. Under low excitation fluences, the VO₂ films exhibit three sequential dynamic processes with different time scales from femtoseconds (fs) to nanoseconds (ns). Depending on the film thickness and excitation fluence, a phase transition is observed in the 148 nm VO₂ film at a time scale of ∼21 ps when the excitation fluence reaches 1.27 mJ cm⁻². However, the 59.5 nm VO₂ film did not undergo a phase transition in this fluence. The femtosecond nonlinear optical properties of the two VO₂ films were also investigated via a Z-scan technique. The nonlinear absorption coefficients and nonlinear refractive coefficients of the VO₂ films at a wavelength of 515 nm are ${\beta }_{148{\rm{nm}}}^{{\rm{eff}}}$ = 1220 ± 100 cm GW⁻¹, ${\beta }_{59.5{\rm{nm}}}^{{\rm{eff}}}$ = 1020 ± 90 cm GW⁻¹, ${\gamma }_{148{\rm{nm}}}^{{\rm{eff}}}$ = −4.3 ± 0.7 × 10⁻³ cm² GW⁻¹, and ${\gamma }_{59.5{\rm{nm}}}^{{\rm{eff}}}$ = −2.1 ± 0.5 × 10⁻³ cm² GW⁻¹, respectively. Compared with the reported values in the near-infrared wavelengths, the nonlinear absorption coefficients exhibit an order of magnitude enhancement.

Despite their many advantages, the widespread application of magnesium (Mg) alloys is hindered by their high corrosion rates and poor ductility and formability. One effective method for enhancing both the corrosion resistance and mechanical properties, such as ductility, of Mg alloys is through alloying with Rare Earth (RE) elements. These elements have recently garnered significant attention due to their beneficial properties, including an electrode potential similar to that of Mg and their capacity to refine grain size, which contributes to reduced corrosion rates and enhanced alloy strength. This paper explores the common forms of Mg corrosion and elucidates the mechanisms by which RE elements improve corrosion resistance and mechanical behavior in Mg-RE alloys. It also provides a detailed analysis of how each RE element alters the corrosion behavior of Mg-based alloys. By integrating RE elements, it is possible to control corrosion and improve mechanical properties through mechanisms like solid solution strengthening, grain refinement, and the formation and distribution of secondary phases.

Heat transfer enhancement has become an important research area to improve the efficiency of thermal systems. This chronological review focuses on approaches for heat transfer enhancement by incorporating inputs into strategies. An in-depth review has been carried out with inserts such as twisted tapes, turbulators, vortex generators, dimple surfaces and porous materials to improve heat transfer in a variety of applications like heat exchangers, renewable energy devices, automotive systems and electronic cooling systems. A comprehensive literature review across several decades was conducted to examine the progress in improving heat transfer efficiency. Various numerical, analytical and experimental methods used in the study were examined to correct the processes and effects of different insert designs. The study includes various insert geometries, structures and materials providing a detailed analysis of the state-of-the-art in heat transfer enhancement. The review highlights key findings from studies of various inputs and their effects on heat transfer enhancement. It provides insight into efficiency metrics such as the Nusselt number, coefficient of heat transfer and pressure drop associated with each insertion method. In addition, the chronological presentation allows trends and improvements to be identified in insert-based heat transfer enhancement over the years. The results in various applications show the effectiveness of certain insert geometries and configurations in improving heat transfer performance. This chronological analysis provides a comprehensive overview of the progress in heat transfer enhancement through the use of different approaches. Knowledge gathered from various studies demonstrates the potential of insert-based methods to significantly improve the thermal conductivity of various thermal systems. Insights gained from this study can guide future research efforts, contributing to efficient and sustainable heat transfer technologies that have been developed. The conclusion highlights the importance of continued research in this area to address the growing challenges of thermal management and energy efficiency.

Two-dimensional (2D) Boron Carbon Nitride (BCN) has recently gained significant attention as a convoluted ternary system owing to its remarkable capability to exhibit a wide range of finely tunable physical, chemical, optical, and electrical properties. In this review, we discuss a variety of stable structure forms of BCN nanosheets. In addition, this review provides recent approaches for synthesizing BCN nanostructures, and properties of BCN derivatives. BCN is a promising material for sustainable energy and energy storage devices. Since BCN application is a challenge in the field of energy, we present potential applications of BCN in the field of energy including supercapacitors and batteries, wastewater treatment, electrochemical sensing, and gas adsorption.

The widespread application of synthetic dyes across industries poses significant environmental problems, particularly concerning with degradation of water quality. Concerning the possible solutions, copper oxide (CuO) considered as a feasible candidate. CuO a p-type heterogeneous semiconductor with a bandgap of 1.2–2.71 eV, It is a reasonable choice and widely studied photocatalyst for addressing such challenges. The functionality of CuO deteriorated, when the wavelength exceeded the UV–visible region. In this manner difficulties associated with reproducibility and reusability, as well as rapid electron–hole recombination, prevent the widespread application of this technology. In an attempt to eliminate this defect, researchers have been investigating strategies to activate CuO under visible light, with one promising approach being carbon nanomaterials such as graphene to form carbon-CuO composites. The unique properties of graphene, i.e., its higher surface area and excellent electron mobility, make it a remarkable candidate for the enhancement of CuO photoactivity. This study highlighted the recent progress in the synthesis of graphene-based CuO photocatalysts, with the main characteristic of extending the light absorption capacity of CuO into the visible spectrum. It reveals achievements in material innovations and applications, with a focus on photocatalytic. It has been observed from the documented studies, catalysis is considered as next generation emerging field for the researcher.

Within a decade, the power congversion efficiency (PCEs) of metal-halide perovskite solar cells (PSCs) moves upward from 3.9% to 25.7%, making them competitive with current state-of-the-art silicon-based counterparts. This steepest growth of the PCEs suggests that the commercialization of this technology might be easing the energy transition from fossil fuel to renewable energy. However, a wide range of factors restrict the commercial viability of PSCs like their toxicity and instability. A crucial and difficult task in the field of PSCs is the replacement of Pb-based perovskite with non-toxic and eco-friendly material while maintaining high-performance with improved stability. Cs₂AgBiBr₆ halide double perovskites (HDP) material seems to be very promising in this regard. This article reviews the recent progress in Cs₂AgBiBr₆ double PSC devices, especially fabrication techniques including the advancement of its efficiency and stability. Here, the evolution of Cs₂AgBiBr₆ towards the application and fabrication of PSCs has also been discussed. This study also analyzed the impact of numerous environmental stresses, such as mechanical, thermal, and optical stresses including the potential prospects in the case of Pb-free PSCs.

In light of the growing security concerns surrounding bridge image data, which can result in economic losses or even pose national security risks due to potential data breaches, this research introduces a novel 2D-QMCCCOM hyperchaos model. This model, developed through extensive theoretical analysis, integrates the quantum Monte Carlo method with coupled clustering theory and chaos dynamics. It addresses the shortcomings of conventional chaos models, such as limited interpretability, a restricted chaotic range, and subpar security capabilities. The model demonstrates superior encryption prowess, with a Lyapunov index of 37.2619, a sample entropy of 2.0591, and a 0-1 test score of 0.9916, outperforming existing chaos-based models in key performance metrics. The application of this chaotic model to image encryption is achieved by generating encryption keys utilizing hash functions, which are then employed to disrupt pixel correlations through a comprehensive process that includes pixel diffusion and permutation. This approach substantially bolsters the encryption's resilience. The encryption scheme excels in performance, with a Peak Signal-to-Noise Ratio (PSNR) of 8.5832, a Structural Similarity Index (SSIM) of 0.009448, a vast key space, high key sensitivity, robust pixel independence, and strong defenses against statistical and differential attacks. Furthermore, the algorithm has been effectively deployed in engineering settings, underscoring its practical utility and feasibility. By tackling the persistent challenges associated with chaos-based encryption, this study presents an innovative and efficient solution to fortify the informational security of bridge management systems.

With the advancement of industrial intelligence, laser welding has been increasingly adopted across various sectors. However, aluminum alloy laser welding is prone to weld defects. Previous research has predominantly focused on the effects of oscillation frequency on weld morphology, while limited attention has been paid to its influence on microstructure evolution and fatigue performance. This study investigates the impact of dual-laser beam oscillation frequency on weld quality, fatigue behavior, and the prediction of fatigue limits at 60 Hz and 90 Hz. Thermal simulations revealed the temperature field distribution under different oscillation frequencies. Results indicate that increasing the oscillation frequency elevates heat input at the weld center but reduces it at the weld edges, leading to a decreased depth-to-width ratio of the weld. Mathematical modeling further demonstrated that higher oscillation frequencies enhance fatigue performance, consistent with prior observations linking increased frequencies to improved tensile strength. Notably, at 90 Hz, porosity is significantly reduced, and spherical grain formation is promoted. These microstructural improvements not only enhance static mechanical properties but also extend fatigue resistance. The suppression of porosity and refinement of grain boundaries effectively hinder crack initiation and propagation, thereby elevating the fatigue limit. This study provides critical insights into optimizing oscillation parameters for high-performance aluminum alloy laser welding in intelligent manufacturing applications.

This work explored designing a solar cell to utilize sub-bandgap photons along with conventional above-bandgap photons using a periodic stack of MASnI3 and MASnBr3 perovskite layers. Based on the stacking pattern, two distinct configurations emerge. First, an ultrathin wide bandgap MASnBr3 layer is embedded in a narrow bandgap MASnI3 absorber, creating a potential hill that favours tunneling transport. In the second configuration, an ultrathin narrow bandgap MASnI3 layer is embedded in wide bandgap MASnBr3 absorber, making a potential well that supports thermionic emission dominated transport. The proposed superlattice design functions similarly to multi-energy level, enhancing the utilization of the incident spectrum by capturing sub-bandgap photons and reducing thermalization. We evaluated these tunneling and thermionic emission dominated device configurations across various operational aspect including carrier transport, recombination, and enhancement in incident spectrum utilisation. The physical parameters controlling device performance such as barrier height, thickness are optimized. The optimal efficiency observed was 35.7%, higher than the Schokley-Quisser limit. This new proposed device paves the way toward high-efficiency solar cell design for light-conversion applications.

This study employs ab initio density functional theory (DFT) combined with the exact muffin-tin orbitals (EMTO) method and coherent potential approximation (CPA) to systematically investigate the structural and mechanical properties of TiVNbMo-based refractory high-entropy alloys (RHEAs) doped with 4d transition metals (Zr, Rh, Ag). Equiatomic TiVNbMoM (M = Zr, Rh, Ag) and non-equiatomic Ti(1-x)VNbMoMx, TiV(1-x)NbMoMx, TiVNb(1-x)MoMx and TiVNbMo(1-x)Mx (with M = Zr, Rh, Ag; 0 ≤ x ≤ 1), were analyzed to evaluate phase stability, lattice parameters, elastic constants, and mechanical moduli. Results confirm the dominance of the body-centered cubic (bcc) phase in all equiatomic alloys, with valence electron concentration (VEC = 4.8–6.2) and atomic size difference (δ = 3.65–6.18%) aligning with solid-solution formation criteria. However, Zr doping reduces bcc stability by lowering average d-electron occupancy, while Rh and Ag retain bcc dominance. Zirconium significantly expands the lattice parameter, whereas Rh reduces it. Mechanical analysis reveals that Rh enhances hardness in Rh-rich compositions, while Zr substitution at Ti sites improves ductility. All systems exhibit ductility (B/G > 1.75; ν > 0.31). This study provides the first theoretical exploration of Rh and Ag doping effects on TiVNbMo RHEAs, demonstrating Rh's unparalleled hardening capability and Zr's dual role in lattice expansion and ductility enhancement. These findings, validated against experimental lattice constants and hardness, as well as theoretical elastic constants and moduli, require further experimental studies to confirm and extend the theoretical predictions.

The influence of high-fluence electron irradiation on the optical and mechanical properties of ZnSe single crystals was systematically investigated. ZnSe samples synthesized via chemical vapor deposition were irradiated with 2 MeV electrons at fluences up to 2.5×1017 electrons/cm2. The optical band gap, Raman spectra, and microhardness of the samples were analyzed before and after irradiation. The results demonstrate that electron irradiation induces a decrease in the ZnSe band gap from 2.596±0.002 eV to 2.580±0.002 eV, attributed to the formation of irradiation-induced defects and associated sub-bandgap states. Raman spectroscopy revealed an increase in the intensity of the longitudinal optical (LO) phonon mode at 251 cm−1 and a reduction in the transverse optical (TO) mode at 205 cm−1, indicating defect-induced modifications in phonon scattering and lattice dynamics. Additionally, microhardness measurements showed an exponential increase of 17.3%, suggesting that irradiation-induced defect interactions and changes in dislocation density contribute to mechanical strengthening. These findings provide valuable insights into the effects of electron irradiation on ZnSe and offer a pathway for tailoring its optical and mechanical properties for radiation-resistant optoelectronic applications.

In this paper, we characterize all discrete-time systems in quasi-standard form admitting coalgebra symmetry with respect to the Lie–Poisson algebra ${{\mathfrak{h}}}_{6}$. The outcome of this study is a family of systems depending on an arbitrary function of three variables, playing the rôle of the potential. Moreover, using a direct search approach, we classify discrete-time systems from this family that admit an additional invariant at most quadratic in the physical variables. We discuss the integrability properties of the obtained cases, their relationship with known systems, and their continuum limits.

Following a comprehensive analysis of the historical literature, we model the geometry of the Stern–Gerlach experiment to numerically calculate the magnetic field using the finite-element method. Using this calculated field and Monte Carlo methods, the semiclassical atomic translational dynamics are simulated to produce the well-known quantized end-pattern with matching dimensions. The finite-element method used provides the most accurate description of the Stern–Gerlach magnetic field and end-pattern in the literature, matching the historically reported values and figures.

This study establishes a unified approach to utilising symmetry methods to uncover diverse analytical solutions and provides deeper insights into the nonlinear phenomena governed by the Kadomtsev-Petviashvili (KP) framework. The (3+1) dimensional generalized Kadomtsev-Petviashvil (gKP) equation with arbitrary nonlinearity f(u) is examined for its underlying symmetry properties, optimal systems, and exact solutions. We employ Lie symmetry methods to classify the algebraic structure and develop one-dimensional optimal systems for different nonlinearities, including power and exponential forms of f(u). Additionally, using square-law nonlinearity, we derive the modified Korteweg-de Vries-Kadomtsev-Petviashvili (mKdV-KP) equation, which is then subjected to symmetry analysis. By utilising the invariants, we systematically reduce the (3+1)-gKP equation to lower-dimensional forms, facilitating the discovery of static and travelling wave solutions. Notably, the square-law nonlinearity reveals rich solution behaviour, which includes elliptic and Jacobi function representations. Furthermore, graphical illustrations provide a better understanding of underscoring their relevance to soliton theory and nonlinear wave dynamics.

We report on the defect engineering in n-type Bi1.8Sb0.2Te3 end-compound via Te non-stoichiometry (Bi1.8Sb0.2Te3-x) intending to enhance the thermoelectric performance at low and near room temperature regime (10 - 350 K). Contemplating the asymmetry in electronic and phonon transport, the extrinsic anionic disorders successfully modulate the thermoelectric transport. Systematic manipulation of Te and Bi/Sb vacancies increases the electrical conductivity, leading to the highest power factor of 534 μW/mK2 at 350 K. The self-doping effect created via anionic disorders resulted in an enhancement in the thermoelectric performance compared to the Bi1.8Sb0.2Te3 compound. Increased ZT values, accompanied by the thermoelectric quality factor, confirm the quality factor as one of the decisive parameters in elevating the thermoelectric performance. The sample with x = 0.08 has the highest ZT value of 0.081 at 350 K. A 174% increase in compatibility factor is also observed, indicating the state-of-the-art applicability of Bi1.8Sb0.2Te3 in segmented thermoelectric generators.

We perform a computational study of very low-pressure gas breakdown phenomena in a perpendicular electric field and applied magnetic field configuration (i.e., ExB discharge) with high-frequency oscillations of the electric field. This work is particularly relevant to an ionization stage of proposed two-stage air-breathing electric propulsion (ABEP) devices, operating in the rarefied atmosphere of very low Earth orbit (VLEO) satellites. In the ionizer, radio-frequency (RF) power is delivered between parallel plates, and the setup is classified as a capacitively coupled RF discharge. A one-dimensional three-velocity (1D-3V) particle-in-cell Monte-Carlo collision (PIC-MCC) technique is employed for the study with nitrogen gas as a surrogate to represent the rarefied atmosphere of VLEO. For ambient pressures less than 1 mTorr, a static magnetic confinement combined with high RF electric field excitation is necessary to efficiently trap electrons and achieve ignition. Observations indicate that for low initial seed electron density of ∼10¹³ m⁻³ and frequencies of ∼100 MHz, gas breakdown requires RF voltages > 2 kV. At higher operating frequencies of about 300 MHz, gas breakdown can be achieved for lower RF voltage of about 500 V. The results indicate that a stochastic, i.e. collisionless, electron heating is a dominant heating mechanism at examined low pressure regimes of 0.1 mTorr. Under these conditions, interactions between electrons and the sheath during its expansion phase produce a high-energy electron beam which is essential for sustaining an enhanced ionization rate. The generated high-energy electrons lead to bounce resonance heating (BRH) due to repeated reflections by the oscillating sheath. Furthermore, with a driving voltage of 500 V and at a high excitation frequency of 300 MHz, an observed resonance with the plasma frequency appears to improve electron confinement and ionization, particularly under the lowest gas pressure and plasma density investigated in this study.

We introduce quantum analogs of the classical flow and orbit objects based on the usual quantum time evolution of wave functions described in terms of energy eigenkets, in contrast to other approaches that use a particular wave ket in their definitions or methods that use a transformation of wave functions. This approach's advantage is that the results are independent of a particular wave function and use standard concepts. We obtain coherent-like states for any potential function. The quantum trajectories are waves that move without changing shape along a classical orbit. We can find quantum effects even for linear potential functions, which is impossible with quantization by deformation methods. We illustrate the meaning of these quantities with simple, analytic examples.

The massive, real scalar field described by the Klein–Gordon equation in one spatial dimension is the most elementary example of a bosonic quantum field theory. It has been investigated for many decades either as a simple academic theory or as a realistic emergent many-body theory in low-dimensional systems. Despite this, the space and time behavior of its propagators have rarely been in the foreground, and although exact results are known, there remain gaps in the description and a lack of an in-depth physical analysis. The aim of this paper is to address the deficits by providing a comprehensive discussion of the results, and to show that this old theory still allows for several new results and insights. To start, we review the known results by providing a rederivation in full detail, to which we add a discussion on how exactly space and time variables need to be extended to complex values to ensure analyticity throughout spacetime. This procedure shows also how singularities on the lightcone need to be regularized to remain compatible with the analyticity and the physical limit of a vanishing mass. An extension to nonzero temperatures is provided by considering the contact of the field to a nonrelativistic thermal reservoir, such as is necessary for emerging field theories in condensed matter systems. Subsequently, it is shown that the transient, short spacetime propagation can be understood in the context of the modern development of a generalized Gibbs ensemble, which describes a massless theory with an effective temperature that is set by the Klein–Gordon mass and the physical temperature. Finally, an approximation scheme is presented that captures the non-trivial mass dependence of the propagators throughout all spacetime but involves only elementary functions.

We present a study on aluminum-doped nickel oxide nanostructured thin films synthesized via spray pyrolysis for ammonia gas sensing applications. Structural analysis confirms the polycrystalline nature of NiO, with the most intense diffraction peak along the (111) plane. Al doping induces variations in surface roughness and optical bandgap, as evidenced by morphological and optical studies. The presence of defects, including oxygen and nickel vacancies, is confirmed through room-temperature photoluminescence and Raman spectroscopy, with x-ray photoelectron spectroscopy further validating an increase in defect concentration upon doping. Gas sensing measurements demonstrate sensor responses of 1.07 and 0.95 for 4% and 6% Al-doped NiO films, respectively, at a low NH₃ concentration of 4 ppm. The enhanced sensing performance of Al-doped NiO nanostructures highlights their potential as an effective sensor layer for low-concentration NH₃ detection in practical applications

In this study, it is aimed to produce triple layer TiO₂/HfO₂/SiO₂ thin films by spin coating method and to minimize optical losses. The characterizations in the study were primarily carried out using XRD, SEM and transmittance and reflectance analyses. The average optical transmittance (400–700 nm) of single layer SiO₂, TiO₂ and HfO₂ film coated silicon substrates were obtained as 93.7%, 82.9% and 86.62%, respectively. The average transmittances for double layer TiO₂/HfO₂ and Triple layer TiO₂/HfO₂/SiO₂ thin films were obtained as 89.41% and 95.44%, respectively. The band gap values of TiO₂, HfO₂ and SiO₂ thin films produced as single layer were calculated as 3.89 eV, 5.62 eV and 5.52 eV, respectively. The average reflectance (380-1100 nm) for single layer films was measured as 13.26%, 10.52% and 17.76% for TiO₂, HfO₂ and SiO₂, respectively, while the triple layer TiO₂/HfO₂/SiO₂ configuration showed a significant decrease in the average reflectance, reaching 7.74% (380–1100 nm), while a minimum reflectance value of 0.3% was obtained at 605 nm.

The use of CO2 to partially replace traditional propellants in electric propulsion (EP) offers cost-effectiveness and good performance. This study investigates the impact of CO2/Xe mixing ratios on Kaufman ion thruster plume characteristics through experiments. The plume characteristics of a Kaufman ion thruster are studied under different mixing flow rates and anode currents, while the underlying mechanisms of plasma formation in the mixed-medium thruster are explored. Results show that increasing the anode current and Xe flow rate promotes plasma generation, reduces electron temperature, and increases ion density. The addition of small amounts of CO2 in the discharge chamber enhances thruster performance by reducing beam divergence, increasing ion density, and minimizing charge-exchange (CEX) ion reflux. However, further increases in CO2 flow rate leads to deterioration in plume characteristics. An optimal CO2/Xe mixture ratio of 1:1 under the tested conditions is demonstrated, which yielded superior beam performance characteristics.