- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2019 IEEE 6th International Symposium on Electromagnetic Compatibility (ISEMC) - Nanjing, China (2019.11.1-2019.11.4)] 2019 IEEE 6th International Symposium on Electromagnetic Compatibility (ISEMC) - Spoof Plasmon Resonance with Terahertz 1-D Periodic Rectangular Filled Refractive Index Sensor
摘要： the dispersion properties of spoof surface plasmon polaritons with 1D rectangular groove structure by analytical solution and numerical solution respectively is analyzed, and the FEM method was used to simulate the refractive index sensing of SPR in terahertz band in an Otto configuration. From the simulation results, we can see that the 1D periodic groove has strong field constraint ability in THz regime as well as in optical band, and the variation of reflection coefficient with incident angle and frequency is very sensitive to the refractive index of the analyte. These results provide a new approach to sample detection and THz regime refractive index sensing, which has great advantages in biomedical tissue detection and sample detection in the future.
关键词： FEM,Spoof Spps,dispersion,THz sensing,groove
更新于2025-09-19 17:13:59
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Ultrathin Self-feeding Metasurface with Broadband Polarization Conversion and Electromagnetic Emission
摘要： A model for controlling the two-dimensional distribution of negatively charged nitrogen-vacancy (NV?) fluorescent centers near the surface of a diamond crystal is presented, using only a microwave plasma-assisted chemical vapor deposition (CVD) method. In this approach, a CVD diamond layer is homoepitaxialy grown via microwave plasma-assisted CVD using an isotopically enriched methane (12CH4 ), hydrogen (H2 ), and nitrogen (N2 ) gas mixture on patterned diamond (0 0 1). When the surface is imaged by means of confocal microscope photoluminescence mapping, fine grooves are observed to have been generated artificially on the diamond surface. NV? centers are found to be distributed selectively into these grooves. These results demonstrate an effective means for the formation of NV? centers of selectable size and density via microwave plasma-assisted CVD, with potential application in the production of diamond quantum sensors.
关键词： doping,nitrogen-vacancy centers,homoepitaxial,groove structure,Diamond,microwave plasma-assisted chemical vapor deposition
更新于2025-09-19 17:13:59
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Investigation of angular log-periodic folded groove waveguide slow-wave structure for low voltage Ka-band TWT
摘要： In this paper, a novel angular log-periodic folded groove waveguide (ALFGW) slow-wave structure (SWS) has been investigated theoretically and experimentally for application in Ka-band traveling-wave tubes (TWTs). The dispersion relation for the ALFGW is derived analytically, and the dispersion characteristics are calculated for a Ka-band design. The designed SWS is fabricated using oxygen-free-copper that is silver electroplated. The measured cold-test parameters show good agreement with the simulation results, with S21 varying from ?2.7 dB to ?4.8 dB and S11 better than ?13.6 dB over the frequency range of 30–38 GHz. Simulations of beam–wave interactions using a 4850 V and 0.4 A sheet beam with a high aspect ratio of 28:1 indicate an output power of 128 W, corresponding to a maximum gain and electronic efficiency of 18.1 dB and 6.6%, respectively. Due to the log-periodic form, a higher output power, higher efficiency, wider bandwidth, and lower operating voltage are achieved as compared to a TWT based on the conventional folded groove waveguide (FGW) SWS. These results show that the proposed ALFGW SWS has good potential for application in relatively high-power wideband TWTs.
关键词： angular log-periodic folded groove waveguide,beam–wave interaction,slow-wave structure,Ka-band,traveling-wave tubes
更新于2025-09-19 17:13:59
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Effects of groove constraint space on plasma characteristics during Laser-MIG hybrid welding of Titanium alloy
摘要： Laser-MIG hybrid welding with groove shows great potential in thick plate joining. However, the plasma behaviors in?uenced by the groove space are not well understood. In this paper, special stair-stepping plates with groove were designed to form di?erent groove con?gurations, and the e?ects of groove depth on the plasma characteristics were investigated systematically. The results showed that the plasma temperature decreased from 10,589 K to 8,527 K and the electron density increased from 1.30 × 1016 cm?3 to 1.44 × 1016 cm?3 when the groove depth increased from 0 to 20 mm. The reason may be that more laser-induced metal vapor, cooler than arc plasma, cannot leave the deeper groove space in time. The heat convection and radiation between the vapor and plasma resulted in the temperature decrease. Besides, as the groove constraint space increased, the plasma pro?le, frequency of droplet-transfer and weld width decreased, while the penetration depth increased to some extent. This research results would be inspirational and meaningful to the laser-arc hybrid welding of medium and thick plate.
关键词： Plasma,Titanium alloy thick plate,Laser-MIG hybrid welding,Groove constraint space
更新于2025-09-16 10:30:52
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3-D-Printed Modified Butler Matrix Based on Gap Waveguide at W-Band for Monopulse Radar
摘要： This article presents the design and fabrication of low-loss, -weight, and -cost, modified Butler matrix in groove gap waveguide technology at W-band, implemented by additive manufacturing. The design, simulations, and measurements of the elements that conform to the modified Butler each of matrix are presented. The proposed modified Butler matrix is asymmetric and oriented to an easy assembly with a radial antenna in order to obtain simultaneous sum and difference patterns for a narrowband radar application. The measured individual components of the modified Butler matrix fit very well with the simulations. As for the full modified Butler matrix, measurements provide a 0.7% bandwidth below ?20 dB for sum and difference ports centered at 94 GHz. The amplitude and phase imbalance are below 1.5 dB and 20?, respectively. This narrow bandwidth is due to the difference in length between input and output ports due to the asymmetry of the design. The total losses of the modified Butler matrix are below 1 dB.
关键词： low profile,distribution network,Additive manufacturing,butler matrix,low cost,W-band,point-to-point communications,low weight,groove gap waveguide (GGW),radar,low loss,monopulse,space debris
更新于2025-09-16 10:30:52
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Multi-objective Optimization of Nanosecond Pulsed Laser Microgrooving of Hydroxyapetite Bioceramic
摘要： This paper presents an experimental study of laser microgrooving on the surface of Hydroxyapetite in its pure form with low power nanosecond pulsed Nd:YAG laser. The laser grooving parameters, namely Lamp current, pulse frequency, assist air pressure, and cutting speed are optimized with respect to overcut and groove depth which are chosen as machining responses. Taguchi methodology for four factors at three levels is used here for the implementation of experiments. Grey relational analysis (GRA) is applied to convert the multiple quality characteristics to a single performance characteristic called grey relational grade from where optimal process parameters are determined. Analysis of variance is carried out to identify the most significant factor for the overall quality characteristics of the laser grooving process. Results of confirmation experiments indicate at the application feasibility of the Taguchi based grey technique for laser grooving quality of bioceramics in the medical industry.
关键词： Laser grooving,Grey relation analysis (GRA),Groove depth,Hydroxyapetite bioceramic,OverCut,Taguchi method
更新于2025-09-16 10:30:52
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Laser Dissimilar Joining of Al7075T6 with Glass-Fiber-Reinforced Polyamide Composite
摘要： Dissimilar joining between metal and composite sheets is usually carried out by mechanical or adhesive joining. Laser dissimilar joining between metal and composite sheets could be an alternative to these methods, as it is a cost-effective and versatile joining technique. Previously, textured metallic and composite parts have been held together and heated with a laser beam while pressure is applied to allow the melted polymer to flow into the cavities of the metal part. The main issue of this process relates to reaching the same joint strength repetitively with appropriate process parameters. In this work, both initial texturing and laser joining parameters are studied for Al 7075-T6 and glass-fiber-reinforced PA6 composite. A groove-based geometry was studied in terms of depth-to-width aspect ratio to find an optimal surface using a nanosecond fiber laser for texturing. Laser joining parameters were also studied with different combinations of surface temperature, heating strategy, pressure, and laser feed rate. The results are relatively good for grooves with aspect ratios from 0.94 to 4.15, with the widths of the grooves being the most critical factor. In terms of joining parameters, surface reference temperature was found to be the most influential parameter. Underheating does not allow correct material flow in textured cavities, while overheating also causes high dispersion in the resulting shear strength. When optimal parameters are applied using correct textures, shear strength values over 26 kN are reached, with a contact area of 35 × 45 mm2.
关键词： metal polymer joint,groove aspect ratio,laser structuring,laser direct joining,shear strength
更新于2025-09-16 10:30:52
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High-efficiency Posture Pre-alignment Method for Large Component Assembly via iGPS and Laser Ranging
摘要： A model for controlling the two-dimensional distribution of negatively charged nitrogen-vacancy (NV?) fluorescent centers near the surface of a diamond crystal is presented, using only a microwave plasma-assisted chemical vapor deposition (CVD) method. In this approach, a CVD diamond layer is homoepitaxialy grown via microwave plasma-assisted CVD using an isotopically enriched methane (12CH4 ), hydrogen (H2 ), and nitrogen (N2 ) gas mixture on patterned diamond (0 0 1). When the surface is imaged by means of confocal microscope photoluminescence mapping, fine grooves are observed to have been generated artificially on the diamond surface. NV? centers are found to be distributed selectively into these grooves. These results demonstrate an effective means for the formation of NV? centers of selectable size and density via microwave plasma-assisted CVD, with potential application in the production of diamond quantum sensors.
关键词： doping,nitrogen-vacancy centers,homoepitaxial,groove structure,Diamond,microwave plasma-assisted chemical vapor deposition
更新于2025-09-16 10:30:52
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Nd3+:YAG laser surface processing of moly-chrome film at 1064 nm, 532 nm and 355 nm wavelengths
摘要： A nanosecond pulsed Nd3+:YAG laser was used to generate grooves as well as dimples on the surface of the moly-chrome film. Interaction of laser, operating at the laser wavelengths of 1064 nm, 532 nm and 355 nm, respectively on the target material were investigated. The principal finding is based on the geometrical parameters such as width, depth and recast layer in the case of the groove. Various roughness parameters inside the grooves were studied. Whereas in the case of the dimple, various parameters like dimple diameter, depth and recast laser were analyzed. A study to find the optical reflectivity of the moly-chrome material at different laser wavelengths was conducted. The groove and dimple formed with the laser wavelength of 1064 nm showed a high material removal and re-cast layer compared to 532 nm and 355 nm. The roughness Ra inside the groove formed with the laser wavelength of 1064 nm and 355 nm exhibited a percentage increase of around 68% and 20% compared to the 532 nm.
关键词： Groove,Wavelength,Surface texture,Dimple,Laser
更新于2025-09-12 10:27:22
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - 1.0 THz Backward-Wave Oscillator Based on Novel Helical Groove Rectangular Waveguide
摘要： A novel helical groove rectangular waveguide slow wave structure (HGRW-SWS) is put forward to develop the lower operating voltage and high electron efficiency terahertz backward wave oscillator (BWO). The major advantage of the HGRW structure is its higher interaction impedance, lower ohm loss and lower operating voltage with respect to the typical SWSs such as folded waveguide SWS or double staggered grating SWS especially in the case of higher spatial harmonics. It is found that this kind of SWS can be operating on the n=-2 harmonic with the interaction impedance of more than 1.5 ohms from the analysis of the cold characteristics of the HGRW-SWS. Moreover, the beam-wave interaction results indicate that the BWO based on the HGRW SWS can produce the output power exceeding 0.657 W in the frequency range from 0.894 THz to 1.164 THz.
关键词： helical groove rectangular waveguide,slow wave structure,terahertz,interaction impedance,backward wave oscillator
更新于2025-09-12 10:27:22