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Radiation hardness of cadmium telluride solar cells in proton therapy beam mode
摘要： We evaluated the durability of cadmium telluride (CdTe) solar cells upon proton beam irradiation as well as the possibility of achieving a dosimeter usable in proton beam therapy by applying 100 MeV of pencil beam scanning (PBS) irradiation. Specifically, a 100 MeV proton PBS beam was applied at irradiation doses of 0, 1012, 1013, 1014, and 1015 cm-2. According to the results, the remaining factors (defined as the ratio of the degraded value to the initial value) of open-circuit voltage (Voc), short-circuit current (Jsc), fill-factor (FF), and efficiency (?) which are solar cell performance parameters, were approximately 89%, 44%, 69%, and 30%, respectively, compared to those of the reference cell (without irradiation) at the highest dose of 1×1015 cm-2. In particular, the conversion efficiency, which is the main factor, was approximately 70% of that of the reference cell even at a high fluence of 1×1014 cm-2. In addition, we observed the projected range of the hydrogen atoms based on the PBS beam energy using the Tool for Particle Simulation software and assessed the amount of fluence accumulated in a CdTe cell. As the energy increased, the fluence accumulated inside the cell tended to decrease owing to the characteristics of the Bragg peak of the proton. Thus, the radiation damage to the cell induced by the proton beam was reduced. The results of this study are expected to provide valuable reference information for research on dosimetry sensors composed of thin-film solar cells, serving as the basis for future application in proton beam therapy with CdTe solar cells.
关键词： radiation hardness,proton therapy,dosimetry sensors,PBS irradiation,CdTe solar cells
更新于2025-09-12 10:27:22
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Enhancement of solar cell efficiency via luminescent downshifting by an optimized coverglass
摘要： A novel approach to enhance the solar cell efficiency via employing a luminescent downshifting mechanism is presented in this work. Gold metal ions were diffused into a commercially available sodalime silicate glass using a versatile field-assisted solid-state ion diffusion technique under different experimental conditions. Some of these samples were irradiated with ns-laser to segregate the diffused ions into dimers and trimers to enhance their luminescence characteristics. The consequent structural modifications in the glass matrix were examined using Fourier transform infrared spectroscopy. Optical absorption and luminescence measurements were performed to check the presence of resonant plasmonic absorption of nanoclusters and suitability of the samples as luminescent downshifters, respectively. At UV excitation wavelengths (260 and 340 nm), the doped samples downshifted the solar spectrum compared to their undoped counterparts. Furthermore, ns-laser irradiation of the doped samples significantly enhanced the luminescence intensity in comparison to the unirradiated samples. Real-time performance of these samples was tested by measuring the output power of a Si solar cell covered with the treated coverglass when illuminated with a solar simulator. Finally, the Vicker's micro-indentation was applied to conclude that ionic diffusion increased the glass hardness as well.
关键词： Vicker's hardness,Ionic diffusion,Power conversion efficiency,Solar cell coverglass,Luminescent downshifting,Ns-laser irradiation
更新于2025-09-12 10:27:22
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A multi-mode excitation hardness prediction method based on Controlled Laser Air-Force Detection (CLAFD) technique
摘要： A novel material hardness testing method was proposed based on controlled laser air-force detection (CLAFD) technique. Polyurethane was chosen as the study object. Multi-mode excitation was adopted. Partial least square as the modeling method was used to build the hardness prediction model on the data of laser displacement. Different preprocessing methods were carried out for eliminating the noise of the original data. The results showed the multiplicative scattering model analysis for the data of stress relaxation mode. The results showed that the hardness could be predicted with high precision. The relationship coefficients of the prediction set (Rp) was above 0.90, and the residual prediction deviation (RPD) was more than 2. Furthermore, the Rp of the transient was 0.93, the RPD was 2.51, the excitation time was 1 s, showing that the transient mode performed with precision in high-speed hardness detection. The highest precision was based on the stress relaxation mode, so we did further study on the interval correction (MSC) had the best performance. Among four modes, the relationship coefficients of the prediction set (Rp) was up to 0.99, and the RPD was 3.54 when the time of the stress relaxation mode lasted 60 s. Based on the results above, the prediction ability would improve further when the relaxation time is increased. The study will provide a new real-time, non-destruction and cross-contamination free hardness detection method for material science, especially for those materials such as artificial biological tissue, function food products, etc.
关键词： Hardness prediction,Biological tissue,Cross-contamination-free,Multi-mode excitation,Polyurethane,Controlled laser air-force detection (CLAFD)
更新于2025-09-12 10:27:22
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The homogeneity of multi-textured micro-pattern arrays in a laser shock surface patterning process and its effect on the surface properties of aluminum alloy
摘要： In this study, a laser shock surface patterning process was performed to e?ectively implement hundreds of micro-patterns on a metallic surface through a single laser beam irradiation. Micro-pattern arrays of rectangular, hexagonal, circular, and mesh shapes of various sizes were successfully transferred to the workpiece, and a multi-textured surface structure was realized. In order to improve the homogeneity of the micro-pattern array, it was most e?ective to increase the thickness of the ablation layer. In the case of the thicker ablation layer, it seems that more uniform pressure was transferred to the material because the ablation layer was in a relatively rigid state due to the reduced level of self-deformation. Since the laser shock surface patterning process exerts a strong shock loading along with plastic deformation on the material surface, the hardness value increased mainly around the area subjected to the shock load. The better the homogeneity of the micro-pattern array, the less the deviation in the hardness value. Therefore, it is important to ensure micro-pattern uniformity in order to achieve uniform surface properties. Changes in the contact angle were also observed under various process conditions. After surface patterning, the contact angle increased as the amount of air trapped in the bar region increased. As the laser intensity increased, it was observed that the geometric surface changes were sharp, and the surface structure changed. As a result, the contact between the air and the water droplets decreased, and the contact angle decreased.
关键词： Laser surface pattering,Multi-textured surface,Shock loading,Uniformity,Wettability,Hardness
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Development and investigation of linear Fresnel lens for concentrator space solar arrays
摘要： Highly efficient ultra-lightweight doubled linear Fresnel-lens concentrators of solar light, which operate in tandem with multijunction InGaP/GaAs/Ge solar cells, have been developed and fabricated. The concentrators have a total photoactive area of (50 × 100) mm2, with the total thickness of ≤0.35 mm and optical focus of 32 mm. The Fresnel profile of each linear lens in the concentrator is formed from silicone rubber on ≤ 100 μm radiation-hard glass. The efficiency of the linear lens concentrators was 90% for the AM0 spectrum (1367 W/m2). The efficiency of the concentrators was examined before and after the irradiation and thermal-cycling tests. A 10% decrease in the efficiency of the linear lens concentrators is observed upon irradiation with 1 MeV electrons at a fluence of 3×1015 cm-2 and a <10% decrease upon thermal-cycling after the radiation treatment. The optical efficiency of the linear lens concentrators decreased by 13% after crush-testing with the total damage area being 2.5%.
关键词： solar concentrator,space solar arrays,Fresnel lens,radiation hardness,thermal cycling
更新于2025-09-11 14:15:04
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Experimental Investigation of Laser Surface Transformation Hardening of 4340 Steel Spur Gears
摘要： This paper presents an experimental investigation of laser surface transformation hardening (LSTH) of 4340 steel spur gears using regression analysis. The experimental work is focused on the effects of various LSTH parameters on the hardness profile shape and the hardened depth variation. The investigations are based on a structured design of experiments and improved statistical analysis tools. The experimentations are carried out on AISI 4340 steel spur gears using a commercial 3 kW Nd:YAG laser system. Laser power, scanning speed, and rotation speed are used as process parameters to evaluate the variation of the hardened depth and to identify the possible relationship between the process parameters and the hardened zone physical and geometrical characteristics. Based on the experimental data and analysis of variance, the direct and interactive contributions of the process parameters on the variation of the hardness profile shape and the hardened depth are analyzed. The main effects and the interaction effects are also evaluated. The results reveal that all the process parameters are relevant. The cumulative contribution of the three parameters in the hardened depth variation represents more than 80% with a clear predominance of laser power. The contribution of the interactions between the parameters represents 12% to 16%. The resulting hardness values are relatively similar for all the experimental tests with about 60 HRC. The evaluation of the produced regression models for hardened depth prediction shows limited performance suggesting that the predictive modeling process can be improved.
关键词： design of experiments,analysis of variance,hardness profile,hardened depth,laser surface transformation hardening,AISI 4340 alloy steel,spur gears
更新于2025-09-11 14:15:04
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Mechanical and tribological performance of fiber laser cladded h-BN + SS316 composite on SS316 surface
摘要： Laser cladding is a unique process for adding one material to the surface of another base material by utilizing high energy and coherent laser beam. For the present investigation, h-BN (hexagonal boron nitride) + SS316 composite coating was applied on SS316 substrate surface by fiber laser cladding operations. Under the influence of various input process parameters, the surface morphology, microstructure, X-ray diffraction, clad layer thickness, micro-hardness, and tribological behaviour of the composite coating were examined. The result showed good metallurgical bonding between the clad powder and substrate surface. Surface morphology did not show any pores and cracks on the clad surface. From FESEM analysis, the clad surface was found to be smooth and free from any crack propagation during laser processing. X-ray diffraction analysis showed formation of Fe3N, Cr2N, CrB, B2C5N2, γ- (Ni, Fe), h-BN phases which are responsible for enhancing mechanical and tribological properties of the clad layer. During the study, the micro-hardness of the clad layer was found to increase with an increase in % v/v of h-BN by 2-2.5 times compared (525 HV0.3) to parent material (220 HV0.3). Further, dry sliding wear test was carried out with Pin-On-Disc, showed that the coefficient of friction value decreased significantly from 0.560 (parent surface) to 0.251 (clad surface).
关键词： solid lubricant,micro-hardness,fiber laser cladding,coefficient of friction,h-BN,microstructure
更新于2025-09-11 14:15:04
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Underwater laser hardening of bearing steels
摘要： Water can act as an effective cooling agent during processing of materials. This can be beneficial especially for surface hardening of steels whereby a rapid quenching rate is desired to generate a hard martensitic surface layer. In this study, the underwater laser hardening of bearing steels is experimentally investigated using a fiber laser. The study found that underwater laser hardening increases surface hardness by about 3.5 times than that of the base material which is higher than in conventional laser hardening. Surface hardness as high as 900 HV is achieved when processed with a thin layer of water above the steel surface. However, the depth and width of the laser hardened zone are found to be significantly smaller than in conventional laser hardening. Further analysis revealed that irregular hardened track formed at slower scanning speed due to the convective motion of water and shock wave generation.
关键词： Steel,Water cooling,Hardness,Laser hardening
更新于2025-09-11 14:15:04
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Influence of laser surface melting on the properties of MB26 and AZ80 magnesium alloys
摘要： In the present investigation, laser surface melting (LSM) was performed on MB26 and AZ80 magnesium alloys and their surface properties were evaluated. The finite element method (FEM) was used to calculate the resulting temperature during the laser surface melting process. The melted layer average thickness values were about 296 and 190 μm for MB26 and AZ80 alloys, respectively and the variation in the thickness is mainly attributed to the absorption in laser energy. The average grain size of the LSMed MB26 alloy was decreased about 14.5 times and AZ80 had very finer grains than the MB26 along with the fine distribution of second phases. Further, the X-ray diffraction results revealed that the second phase intensities were decreased in both the alloys due to their dispersion. The laser absorption efficiency of MB26 was higher due to the higher plasma attachment during LSM process, thereby has higher melt layer thickness compared to AZ80. The refined microstructure of the melted layer resulted in an increase of micro-hardness up to 110 Hv. Potentiodynamic polarization test results revealed that the corrosion current density (icorr) values of the LSMed MB26 and AZ80 alloys were decreased about 1.8 and 2.5 times, respectively compared to the as-received alloys. A variation in solidification rates of the melt pool due to the alloying elements were attributed to an improvement in the surface and electrochemical properties.
关键词： Corrosion,Polarization,Laser surface melting,Hardness,Magnesium alloys
更新于2025-09-11 14:15:04
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Sputtering yield measurements of laser ablated Mg-alloy correlated with surface, structural and mechanical modifications
摘要： Sputtering yield of laser ablated Mg-alloy has been measured by Quartz Crystal Microbalance at various fluences ranging from 11.6–44.2 J/cm2, under two different environments of Ar and O2. The sputtering yield initially increases from 14.58 × 1014 to 23.49 × 1014 and from 4.5 × 1014 to 22.60 × 1014 (atoms/pulse) by increasing fluence and then decreases upto a value of 19.78 × 1014 and 19.94 × 1014 (atoms/pulse) at the maximum fluence, under Ar and O2 environment respectively. Scanning Electron Microscope analysis reveals the formation of cones, cavities, droplets, ripples and island like structures on the irradiated Mg surface. Surface profilometry analysis reveals that the crater depth of laser irradiated Mg-alloy ranges from 188 to 209 μm. It initially increases by increasing laser fluence and afterwards, decreases at the maximum fluence. Energy Dispersive X-ray spectroscopy (EDX), X-Ray Diffraction analysis (XRD) and Ultraviolet-Visible (UV–vis) spectroscopy confirm the oxide formation for the laser treated target of Mg in O2. The Vickers Micro-hardness testing reveals that hardness of laser irradiated Mg-alloy is increased by increasing fluence. The surface structures, crater depth and hardness of laser irradiated Mg-alloy are strongly dependent upon laser fluence and are correlated with sputtering yield measurements.
关键词： UV–vis,EDX,XRD,Sputtering yield,Surface modifications,Crater depth,Mg-alloy AZ91D,Micro-hardness
更新于2025-09-11 14:15:04