- 标题
- 摘要
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- 实验方案
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[IEEE IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - D.C., DC, USA (2018.10.21-2018.10.23)] IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - Steady-state equivalent circuit of LED bulbs accounting for the current harmonics
摘要： Nowadays, the light-emitting diode (LED) bulb is one of the preferred choice in lighting system design. Electrical models of the LED lamps have to consider their nonlinear behavior involving current distortion on the mains. With this purpose, an equivalent electrical circuit emulating the current drawn by a LED Bulbs is carried out. In this work, different lamps have been tested under variable supply voltage. The comparison between the simulations performed by means of PSpice and the experimental measurements has highlighted that linear interpolation for the amplitude of each harmonic current, as function of the voltage on the main, provides a good estimation of the total current waveform.
关键词： LED Bulbs,power conversion,LED lamps,Current harmonics,equivalent circuits,lighting,total harmonic distortion,power quality
更新于2025-09-19 17:13:59
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Resonance Enhancement in Laser-Produced Plasmas (Concepts and Applications) || Front Matter
摘要： The motivation in writing this book is to show the most recent findings of newly emerged field of resonance-enhanced high-order harmonic generation (HHG) using the laser pulses propagating through the narrow and extended laser-produced plasma plumes. It becomes obvious that the developments in this field are aimed for improvement of harmonic yield through precise study of resonance effects during fine-tuning of driving pulses to the resonances. The purpose of writing this book is to acquaint the readers with the most advanced, recently developed methods of plasma harmonics generation at the conditions of coincidence of some harmonics, autoionizing states, and some ionic transitions possessing strong oscillator strengths. This book demonstrates how one can improve the plasma harmonic technique using this approach.
关键词： extreme ultraviolet,plasma harmonics,laser-produced plasmas,high-order harmonic generation,resonance enhancement,XUV,nonlinear optics,HHG
更新于2025-09-19 17:13:59
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Laser-driven tunneling photocurrent as a source of midinfrared to microwave multidecade supercontinua yoked to high-order harmonics
摘要： Electron tunneling induced by a strong-field laser driver can lead to an ultrafast stepwise buildup of the photoelectron density ρ. When the laser field is strong enough, each such step in the temporal profile of ρ is confined well within the field cycle, providing an ultrabroadband, multidecade force that drives the photoelectron current j. However, whether or not the photocurrent can emit electromagnetic radiation with such an extraordinarily broad spectrum depends on the damping, which defines the low-frequency cutoff in the spectrum of this radiation. We show that, with a suitable choice of the gas pressure and parameters of the laser driver, the laser-induced tunneling photocurrent can serve as a source of a remarkably broadband electromagnetic radiation with a multidecade spectrum stretching from the vacuum ultraviolet all the way down to the microwave range. We demonstrate that the supercontinuum fields emitted by individual photocurrent steps, induced by different field half cycles, can coherently combine, giving rise to well-resolved high-order harmonics on the high-frequency end of the spectrum yoked to a bright midinfrared to microwave supercontinuum, dominating the long-wavelength part of the multidecade radiation output.
关键词： high-order harmonics,photocurrent,supercontinua,microwave,midinfrared,laser-driven tunneling
更新于2025-09-19 17:13:59
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[IEEE 2018 11th UK-Europe-China Workshop on Millimeter Waves and Terahertz Technologies (UCMMT) - HangZhou, China (2018.9.5-2018.9.7)] 2018 11th UK-Europe-China Workshop on Millimeter Waves and Terahertz Technologies (UCMMT) - A Space Harmonic Leaky-Wave Antenna Based on Half Mode Substrate Integrated Waveguide
摘要： A space harmonic leaky-wave antenna based on half mode substrate integrated waveguide (HMSIW) is proposed. This antenna operates in the first negative mode of the guiding structure which is a space harmonic wave using transverse slots. Continuous backward to forward beam scanning is achieved within 25 ± 10 GHz and the highest gain of the antenna can achieve 24.8dBi. The size of the antenna is half of the HMSIW antenna.
关键词： half mode substrate integrated waveguide (HMSIW),space harmonics,leaky-wave antenna
更新于2025-09-19 17:13:59
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Generation of Neara??Circularly Polarized Attosecond Pulse with Tunable Helicity by Unidirectionally Rotating Laser Field
摘要： A method to produce circularly polarized attosecond pulses with tunable helicity from CO molecule by using an unidirectionally rotating laser field is proposed. It is found that broadband harmonic supercontinuum with circular polarization can be generated from the oriented CO molecule. This enables the production sub-100 attosecond isolated pulse with the ellipticity as high as 0.9 at the macroscopic level. Moreover, the helicity of the generated high-order harmonics and the attosecond pulse can be tuned by adjusting the orientation of the CO molecule. This method will be beneficial for the studies on chiral-specific dynamics and magnetic circular dichroism on an attosecond time scale.
关键词： attosecond pulses,tunable helicity,high-order harmonics,rotating laser fields
更新于2025-09-19 17:13:59
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Selective enhancement of single-order and two-order harmonics from He atom via two-color and three-color laser fields
摘要： An effective method to achieve the selective enhancement of single-order and two-order harmonics from He atom has been proposed through laser waveform control of two-color and three-color laser fields. Firstly, with the optimization of ω-2ω two-color laser waveform, not only the wavelength tunable single-order harmonic (i.e. from 182th order to 328th order) can be enhanced by 17 times compared with the neighbor harmonics, but also the enhancement of two-order harmonics can also be obtained. Theoretical analyses show that the enhancement of the specific harmonics is coming from the folded structure on the short quantum path of the harmonic emission peak. Detail analyses show that the above folded structure happens in the reversed sub-peak region of the half-cycle laser waveform, where the deceleration and further acceleration of the free electron can be found in this structure. Moreover, this structure is dependent on the pulse duration of the controlling pulse. However, it is not very sensitive to the wavelength of the controlling pulse. Further, by properly adding a 3ω pulse, not only the efficiency of spectral continuum can be enhanced by 300 times compared with that from the two-color field, but also the generation of single-order harmonic with the intensity enhancement of 20 times can be found. Furthermore, the enhancement of the harmonic spectrum can also be achieved when using the 4ω or 6ω controlling pulses.
关键词： Selective enhancement of two-order harmonics,Two-color and three-color combined fields,Selective enhancement of single-order harmonics,High-order harmonic generation,Laser waveform control
更新于2025-09-16 10:30:52
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Application of harmonics imaging to focal spot measurements of the “PETAL” laser
摘要： By using numerical simulations and experimental campaigns on a small-scale laser facility, the concept of the focal spot imaging on harmonics of laser frequency is developed and implemented on the Laser MegaJoule (LMJ)/PETawatt Aquitaine Laser (PETAL) facility. The Two/Three ω Imaging System was activated and validated during the first 2017–2019 interaction campaigns of PETAL on the LMJ. It provides major information on focal spot characteristics on a target. Such an approach could be easily applied to any high-intensity facility in the relativistic intensity regime (>1018 W cm?2).
关键词： PETAL laser,harmonics imaging,high-intensity laser-plasma interaction,focal spot measurements
更新于2025-09-16 10:30:52
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[IEEE 2019 Workshop on Recent Advances in Photonics (WRAP) - Guwahati, India (2019.12.13-2019.12.14)] 2019 Workshop on Recent Advances in Photonics (WRAP) - Stand-off Femtosecond Laser Induced Breakdown Spectroscopy of Metals, Soil, Plastics and Classification Studies
摘要： This paper presents one of the first studies of the harmonic impact of a significantly large photovoltaic (PV) solar farm of 20 MW in a utility distribution system. This solar farm is a constituent of the 80-MW PV solar farm in Sarnia, Ontario, which is so far the largest solar farm in Canada. The utility network is modeled in detail using the commercial grade PSCAD/EMTDC software, which is validated through load flow studies conducted by CYME software and correlated with SCADA measurements. The validated network model is used for network resonance study and harmonics impact analysis of the solar farms under different network conditions. The harmonics data instrumented for several months were provided by the transmission utility at the two solar farm units and at the main feeder substation. These data were utilized for extensive harmonic impact studies with widely different short-circuit levels and network resonance conditions. This paper presents the detailed procedure adopted for performing such harmonic impact studies. It is concluded that this large solar farm may not cause any substantial voltage distortion on the distribution network during steady-state operating conditions. However, recommendations are made for utilities to perform such studies to ensure the safe operation of critical loads.
关键词： network resonance,total harmonic distortion,solar energy,harmonics,Distribution systems,total demand distortion,photovoltaic (PV) solar system,frequency scan
更新于2025-09-16 10:30:52
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Disturbances Generated by Lighting Systems with LED Lamps and the Reduction in Their Impacts
摘要： The paper deals with electromagnetic disturbances in the form of current higher harmonics, which are generated by LED lighting elements. It presents the problems related to the formation and impact of higher harmonics in the electrical systems of commercial facilities. The results of tests and analyses of current distortions for two di?erent LED lamps are included, and these are in reference to the parameters set out in the normal applicable standards. A system was then proposed to improve the quality of energy in the mains of commercial facilities in the form of a two-stage power supply. Tests of the systems with the aforementioned LED lamps were conducted and commented upon after introduction of the two-stage power supply. The ?nal part of the paper contains a summary of the obtained test results.
关键词： electromagnetic compatibility,total harmonic distortion (THD),LED lamp,two-stage power supply,current and voltage distortion,lighting system,power factor correction (PFC),higher harmonics
更新于2025-09-16 10:30:52
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[IEEE 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM) - K?rdla, Estonia (2019.6.12-2019.6.15)] 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM) - Power Quality Assessment of Indoor LED Luminaires
摘要： Due to the fact that it is a semiconductor based lighting equipment, the LEDs have important effects on the power quality. In the ever-expanding lighting industry, the use of LED equipment is increasing day by day. Therefore, it is very important to analyze and interpret the effects of LEDs on the grid. In this study, power quality measurements of 4 different commercial LED luminaires have been realized and the results obtained have been interpreted. According to the measurements, it is found that the power factor values are acceptable for the luminaries when they are completely on. However, when the luminaries are dimmed, it has been observed that the power factor decreased and the current harmonics exceeded the limit values determined by the related standards. On the other hand, it is seen that all the luminaires provide flicker boundaries. As a result of the study, it has been concluded that the effects of dimmable equipment on power quality should be analyzed in more detail.
关键词： LED lamps,harmonics,flicker,power quality,power factor
更新于2025-09-16 10:30:52