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Impacts of laser pulse width and target thickness on laser micro-propulsion performance

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Plasma Science and Technology 2022年第10期24卷 113-126页

作者： Sibo WANG Bangdeng DU Baosheng DU Yongzan ZHENG Yanji HONG Jifei YE Baoyu XING Chenglin LI Yonghao ZHANG State Key Laboratory of Laser Propulsion and Application Space Engineering UniversityBeijing 101416People's Republic of China Technical Institute of Physics and Chemistry Chinese Academy of SciencesBeijing 100190People's Republic of China

In order to optimize the laser ablation performance of a micro-thruster with 1U dimensions,which employs a micro semiconductor laser,the impacts of pulse width and glycidyl azide polymer(GAP)thickness on thrust performance were *** results showed that with a GAP thickness of 200μm,the single-pulse impulse(I)increased gradually with the increase in the laser pulse width from 50 to 800μs,while the specific impulse(I_(sp)),impulse coupling coefficient(Cm)and ablation efficiency(η)all reached optimal values with a 200μs pulse *** is worth noting that the optimal pulse width is identical to the ignition delay *** Cmandηpeaked with a pulse width of 200μs,reaching 242.22μN W^(-1)and 35.4%,*** the increase in GAP thickness,I and Cmincreased *** of different thicknesses corresponded to different optimal laser pulse *** a certain laser pulse width,the optimal GAP thickness should be the most vertical thickness of the ablation pit,and the various propulsion performance parameters at this time were also *** the current laser parameters,the optimal GAP thickness was approximately 150μm,I_(sp)was approximately 322.22 s,andηwas approximately 34.94%.

关键词： laser micro-propulsion pulse width target thickness specific impulse ablation efficiency

Evolution of the pulse width in Dielectric Barrier Atmospheric Pressure Discharge

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Plasma Science and Technology 2012年第9期14卷 808-812页

作者：宋新新谭震宇陈波张远涛李清泉 School of Electrical Engineering Shandong University Shandong Labour Vocational and Technology College

A study of the evolution of the pulse width in homogeneous dielectric barrier dis- charge at atmospheric pressure with helium as the working gas is reported by using a one- dimensional fluid model. In this paper, a new computational method is presented to estimate the pulse width through calculating the time interval between the breakdown voltage and the extinguishing voltage. The effects on the discharge characteristics of the applied voltage and exci- tation frequency are studied based on the computational data. The results of the simulation show that the pulse width is observed to be narrower and the time intervals between two consecutive current pulses decrease with increasing amplitude and excitation frequency, which indicates that the homogeneous discharge is susceptible to the filamentary mode. The simulation results support the conclusion that in order to restrain the transition from the glow mode to filamentary mode, the applied voltage and excitation frequency should be kept within an appropriate range.

关键词： pulse width time interval breakdown voltage extinguishing voltage glowmode filamentary mode

Wide pulse width Electroacupuncture Ameliorates Denervation-Induced Skeletal Muscle Atrophy in Rats via IGF-1/PI3K/Akt Pathway

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Chinese Journal of Integrative Medicine 2021年第6期27卷 446-454页

作者： HUANG Xiao-qing XU Jin-sen YE Xiao-ran CHEN Xuan Key Laboratory of Acupuncture Instrument Fujian Academy of Chinese Medical SciencesFuzhou(350003)China Fujian Key Laboratory of Propagated Sensation along Meridian Institute of Meridians and Collaterals MedicineFujian Academy of Chinese Medical SciencesFuzhou(350003)China

Objective:To evaluate the effect of the pulse width of electroacupuncture(EA)in the treatment of denervation-induced skeletal muscle atrophy in rats and examine the role of insulin-like growth factor 1(IGF-1)/phosphatidylinositol 3-kinase(PI3 K)/Akt signaling pathway during ***:Sciatic nerve functional index(SFI),muscle wet weight and the cross-sectional area(CSA)of the gastrocnemius muscle were analyzed after treatment in model rats with EA of various pulse widths(0.5,50,100 and 200 ms).The apoptosis index(AI)and paired box(PAX)3 and PAX7 protein expression were also ***,the mRNA and protein expressions of components of IGF-1/PI3 K/Akt pathway and their downstream targets were determined,along with the inhibiting effect of the pathway with a PI3-specific ***:EA with a pulse width of 200 ms was found to have the best effect with regard to increasing SFI,CSA and muscle weight,decreasing AI,and increasing the expression of PAX3 and *** IGF-1/PI3 K/Akt pathway was found to be activated by denervation,although the downstream forkhead box O(FoxO)pathway was not suppressed by its *** PI3 K/Akt pathway and its downstream molecule mammalian target of rapamycin(mTOR)were up-regulated further by EA to promote muscle protein ***,the expressions of downstream FoxO and F-box protein 32(ATROGIN-1)were down-regulated to reduce protein ***:EA with 200-ms pulse width was found to have a more significant effect than 0.5-ms *** positive effects of EA disappeared after inhibition of the PI3 K/Akt pathway.

关键词： denervation muscle atrophy electroacupuncture pulse width IGF-1/PI3K/Akt pathway

Effect of Peak Power and pulse width on Coherent Doppler Wind Lidar’s SNR

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Instrumentation 2022年第2期9卷 26-32页

作者： REN Yong WU Xuefei TAO Fa CAO Haishuai Fujian Key Laboratory of Severe Weather Fuzhou 350001 Meteorological Observation Center of the China Meteorological Administration Beijing 100081 Fujian Atmospheric Detection Technology Support Center Fuzhou 350008 Qingdao Leice Transient Technology Co.Ltd Qingdao 266000

The laser device is the core component of coherent Doppler wind *** peak power and pulse width of laser transmitting pulse have important effects on *** on coherent Doppler wind pulse lidar,the peak power and pulse width influence on SNR is studied on the theoretical derivation and analysis,and the results show that the higher the peak power can realize the greater the signal-to-noise ratio of coherent Doppler wind *** when the peak power is too large,the laser pulse may appear nonlinear phenomenon,which cause the damage of the ***,the peak power must be less than the stimulated brillouin scattering power *** the pulse width can make the laser device to output more energy,but it will also make the spatial resolution lower,and the influence of turbulence on SNR will be *** a series of simulation analyses,it can be concluded that when the peak power is 650W and the pulse width is 340ns,the SNR of the system can be *** addition,the coherent Doppler wind lidar system is set up to carry out corresponding experimental *** experimental results are consistent with the theoretical analysis and simulation,which verifies the correctness of the theoretical analysis and simulation *** provides theoretical basis and practical ex-perience for the design of laser transmitting pulse in coherent Doppler wind lidar system.

关键词： Coherent Lidar Fiber Laser Peak Power pulse width Signal-to-Noise Ratio(SNR)

EFFECT OF ULTRASOUND pulse width ON CAVITATION IN SMALL-SIZE REVERBERATION

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Progress in Natural Science:Materials International 1992年第3期 275-279页

作者：王双维冯若许坚毅史群 Changchun 130024 Department of Chemistry Department of Physics Northeast Normal University Institute of Acoustics Nanjing 210008 Nanjing University PRC

Ⅰ.INTRODUCTIONBased on the authors’previous studies on the CW ultrasonic cavitation in the travellingwave field,this note investigates the pulse sonic cavitation of the reverberation *** ultrasound waves,with sound intensity 1.75 W/cm~2,frequency 823 kHz,pulse from100 μs up to 30 s and on/off=1:1,are used to irradiate the sample of terephthalicacid (TA) solution with the concentration 2 mmol/L,where TA is not a kind of fluorescentmatter,and when it combines with free radical OH produced by ultrasonic cavitation,

关键词： small-size reverberation field pulse width production rate of cavitation nucleus

The characteristics of sonoluminescence

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Chinese Physics B 2012年第1期21卷 499-506页

作者： An Yu Zhang Wen-Juan Department of Physics Tsinghua UniversityBeijing 100084China

Cavitation luminescence is light emission from gases that are compressed to high temperature and high pressure inside a bubble or group of bubbles. The numerical simulation in this study indicates that if the temperature and pressure inside a bubble are not high enough, then dim and spectral line emission dominates. However, if the temperature and pressure inside the bubble are very high, then the light is bright and a continuum spectrum will be generated. Calculations of the spectrum using modified equations of bubble motion can simulate the spectral profile well. However, pulse width calculations using these equations only partly agree with the experimental results.

关键词： sonoluminescence spectrum pulse width

Efficient Diode-Pumped Passively Q-Switched Nd-GdVO4 Lasers

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Chinese Physics Letters 2002年第12期19卷 1808-1810页

作者： Liu Jie, Jia Yu-Lei, Yang Ji-Min Laboratory of Modern Optics Shandong Normal University

An efficient diode-pumped Nd:GdVO4 laser passively Q-switched by a Cr^4+:YAG has been developed as a saturable absorber. A KTP crystal is used for the extra-cavity second-harmonic generation and a BBO crystal for the sum frequency mixing. The green output power is 172 mW at incident pump power of 8 W. The ultraviolet (UV) output power is measured to be 20 mW at the same pump power. The peak power of the UV laser is 143 W with the pulse repetition rate of 14 kHz and pulse width of 10 ns.

关键词： pulse REPETITION RATE Power Saturable absorbers ultraviolet laser light maximum loads sum frequency power Second-harmonic generation Power pulse width Pumps Output power Power (Psychology) Ultraviolet Rays Energy sources

Performance of the Self—Q—Switched Cr,Yb：YAG Laser

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Chinese Physics Letters 2002年第3期19卷 342-344页

作者：董俊邓佩珍等 ShanghaiInstituteofOpticsandFineMechanics ChineseAcademyofSciencesShanghai201800

We report on the spectral properties of Cr,Yb:YAG crystal co-doped with 0.025 at.% Cr and 10 at.% Yb are reported. Using a continuous wave Ti:sapphire laser as a pumping source, we have demonstrated the self-Q-switched Cr,Yb:YAG laser at room temperature. We obtained an average output power as much as 75 mW at 1.03 μm with a pulse width (FWHM) as short as 0.4 μs. The laser experiment demonstrated that the Cr,Yb:YAG crystal exactly combines the Cr^4+ saturable absorber and Yb^3+ gain medium. The Cr,Yb:YAG crystal can be a most promising self-Q-switched laser crystal for compact and efficient solid-state lasers.

关键词： average output power Pumping crystals Laser solid state lasers Ytterbium pulse width pump source spectral characteristic

Voltage adjustment improves rigidity and tremor in Parkinson's disease patients receiving deep brain stimulation

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Neural Regeneration Research 2018年第2期13卷 347-352页

作者： Shao-hua Xu Chao Yang Wen-biao Xian Jing Gu Jin-long Liu Lu-lu Jiang Jing Ye Yan-mei Liu Qi-yu Guo Yi-fan Zheng Lei Wu Wan-ru Chen Zhong pei Ling Chen Department of Neurology National Key Clinical Department and Key Discipline of NeuroloryThe First Affiliated HospitalSun Yat-senUniversityGuangzhouGuangdong ProvinceChina Department of Neurosurgery First Affiliated Hospital of Sun Yat-sen UniversityGuangzhouGuangdong ProvinceChina Department of Medical Statistics and Epidemiology School of Public HealthSun Yat-sen UniversityGuangzhouGuangdong ProvinceChina Department of Neurology Tangshan Worker's HospitalTangshanHebei ProvinceChina

Deep brain stimulation of the subthalamic nucleus is recognized as the most effective treatment for moderate and advanced Parkinson＇s disease. Programming of the stimulation parameters is important for maintaining the efficacy of deep brain stimulation. Voltage is consid- ered to be the most effective programming parameter. The present study is a retrospective analysis of six patients with Parkinson＇s disease （four men and two women, aged 37-65 years）, who underwent bilateral deep brain stimulation of the subthalamic nucleus at the First Affiliated Hospital of Sun Yat-sen University, China, and who subsequently adjusted only the stimulation voltage. We evaluated motor symptom severity using the Unified Parkinson＇s Disease Rating Scale Part III, symptom progression using the Hoehn and Yahr scale, and the levodopa equivalent daily dose, before surgery and 1 and 2 years after surgery. The 2-year follow-up results show that rigidity and tremor improved, and clinical symptoms were reduced, while pulse width was maintained at 60 ps and frequency at 130 Hz. Voltage adjust- ment alone is particularly suitable for patients who cannot tolerate multiparameter program adjustment. Levodopa equivalent daily dose was markedly reduced 1 and 2 years after surgery compared with baseline. Our results confirm that rigidity, tremor and bradykinesia can be best alleviated by voltage adjustment. The trial was registered at *** （identifier： NCT01934881）.

关键词： nerve regeneration deep brain stimulation Parkinson's disease subthalamic nucleus voltage pulse width frequency tremor rigidity bradykinesia axial symptoms neural regeneration