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51.
A survey on the mechanisms of powerful terahertz (THz) radiation from laser plasmas is presented.Firstly,an analytical model is described,showing that a transverse net current formed in a plasma can be converted into THz radiations at the plasma oscillation frequency.This theory is applied to explain THz generation in a gas driven by two-color laser pulses.It is also applied to THz generation in a tenuous plasma driven by a chirped laser pulse,a few-cycle laser pulse,a DC/AC bias electric field.These are well verified by particle-in-cell simulations,demonstrating that THz radiations produced in these approaches are nearly single-cycles and linear polarized.In the chirped laser scheme and the few-cycle laser scheme,THz radiations with the peak field strength of tens of MV/cm and the peak power of gigawatt can be achieved with the incident laser intensity less than 10 17 W/cm 2. 相似文献
52.
LOSEV V F PANCHENKO Yu N DUDAREV V V IVANOV N G KONOVALOV I N PAVLINSKY A V PUCHIKIN A V 《中国光学》2011,4(1):1-8
研究了脉冲宽度为25~40ns的放电脉冲XeCl准分子激光器的工作参数。结果显示,激光器产生的脉冲能量为0.2~0.7J,重复频率为100Hz,表明在泵浦功率为2.8~3.3MW/cm。时,激光器实现了2.6%的激光效率和3.8%的本征效率。 相似文献
53.
基波平衡原理在多端口网络的应用 总被引:1,自引:0,他引:1
对于网络仅含一个压控非线性元件,用基波平衡原理由输入导纳G=0,B=0求振荡频率ω和基波振幅Um.如果有合理的(ω,Um)∈R2,则网络存在有周期振荡或混沌振荡.对于网络含有两个压控的非线性元件,可以用埃米特式计算进入双口网络的实功P和虚功Q,由输入功率P=0,Q=0求振荡频率ω和基波振幅Um.如果存在有一组合理的(ω,Um) ∈R2,则网络存在有周期振荡.如果存在有多于两组合理的(ω,Um) ∈R2,则网络存在有混沌振荡. 相似文献
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55.
The primary goal of this paper is to present a comprehensive study of the nonlinear Schr?dinger equations with combined nonlinearities of the power-type and Hartree-type. Under certain structural conditions, the authors are able to provide a complete picture of how the nonlinear Schr?dinger equations with combined nonlinearities interact in the given energy space. The method used in the paper is based upon the Morawetz estimates and perturbation principles. 相似文献
56.
Chun-Chuan Liu · Feng-Ming Li · Ting-Wei Liang · Wen-Hu Huang P.O.Box School of Astronautics Harbin Institute of Technology Harbin China 《Acta Mechanica Sinica》2011,27(5):785-795
In this paper,wave and vibratory power transmission in a finite L-shaped Mindlin plate with two simply supported opposite edges are investigated using the wave approach.The dynamic responses,active and reactive power flow in the finite plate are calculated by the Mindlin plate theory (MPT) and classic plate theory (CPT).To satisfy the boundary conditions and continuous conditions at the coupled junction of the finite L-shaped plate,the near-field and far-field waves are entirely contained in the wave approach.The in-plane longitudinal and shear waves are also considered.The results indicate that the vibratory power flow based on the MPT is different from that based on the CPT not only at high frequencies but also at low and medium frequencies.The influence of the plate thickness on the vibrational power flow is investigated.From the results it is seen that the shear and rotary inertia correction of the MPT can influence the active and reactive power at the junction of the L-shaped plate not only at high frequencies but also at low and medium frequencies.Furthermore,the effects of structural damping on the active and reactive power flow at the junction are also analyzed. 相似文献
57.
适合陆基使用的旋转重力梯度仪采用多个加速度计的组合输出,能有效地抑制平台的共模噪声,实现对地球表面微小重力梯度变化信号的测量.其关键技术之一就是对多个加速度计进行动态匹配调节,通过实时反馈来降低多种噪声和误差,从而降低对研制单个加速度计的性能要求.本文结合旋转重力梯度仪中加速度计的匹配调节方法,以重力梯度测量分辨率达到1E为目标分析,结果表明对加速度计的标度因子一致性匹配需要达到10-11的量级,对二阶非线性因子调节同样需要达到~10-11g/g2的量级. 相似文献
58.
XU Zheng XU Jianyi LIU Xiaojun 《声学学报:英文版》2011,30(3):253-260
Under combined irradiation of laser and ultrasound,cavitary bubbles are generated on the surface of gold nanoparticle.The laser-induced thermal effect,ultrasonic cavitation effect and the synergistic effect of laser and ultrasound are studied by means of the investigation of the dynamical process for the vibration of the cavitation bubble,with different external conditions such as laser power,ultrasound intensity,etc.It is found that dynamical process of the cavitation bubble can be modified by the irradiation of laser or ultrasound.The enhancement of laser power can increase the critical radius of the cavitation bubble,while that of ultrasound may intensify the vibration.Cavitation bubble may become more stable due to the synergistic effect of laser and ultrasound.It is also found that variation of the coupling between laser and ultrasound can affect synergistic effect. 相似文献
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60.
从理论上分析了高功率光纤激光器直接抽运和二级抽运的斜率效率和热管理问题. 计算结果表明:波长为975 nm的激光直接抽运产生波长为1070 nm的激光时,理论斜率效率为80%,但当抽运光功率为10 kW时,在强制水冷条件下纤芯极值温度也难以降到150 ℃以下;在二级抽运技术中,波长为1018 nm的激光抽运产生波长为1070 nm的激光时,若采用传统的包层抽运技术,其斜率效率不足20%,如果抽运功率填充因子由0.0025提高到0.1,则理论上斜率效率可由18.5%提高到80.9%,从而总斜率效率由15.5
关键词:
二级抽运
功率填充因子
斜率效率
热管理 相似文献