共查询到20条相似文献,搜索用时 15 毫秒
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By numerically solving the relativistic equations of motion of a single electron in laser fields modeled by a Gaussian laser beam, we get the trajectory and energy of the electron. When the drifting distance is comparable to or even longer than the corresponding Rayleigh length, the evolution of the beam waist cannot be neglected. The asymmetry of intensity in acceleration and deceleration leads to the conclusion that the electron can be accelerated effectively and extracted by the longitudinM ponderomotive force. For intensities above 10^19 Wμm^2/cm^2, an electron‘s energy gain about MeV can be realized, and the energetic electron is parallel with the propagation axis. 相似文献
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The characteristics of backward harmonic radiation due to electron oscillations driven by a linearly polarized fs laser pulse are analysed considering a single electron model. The spectral distributions of the electron's backward harmonic radiation are investigated in detail for different parameters of the driver laser pulse. Higher order harmonic radiations are possible for a sufficiently intense driving laser pulse. We have shown that for a realistic pulsed photon beam, the spectrum of the radiation is red shifted as well as broadened because of changes in the longitudinal velocity of the electrons during the laser pulse. These effects are more pronounced at higher laser intensities giving rise to higher order harmonics that eventually leads to a continuous spectrum. Numerical simulations have further shown that by increasing the laser pulse width the broadening of the high harmonic radiations can be controlled. 相似文献
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ZHOU Zili LIU Jiansheng LU Haiyang JU Jingjing WANG Cheng XIA Changquan WANG Wentao DENG Aihua XU Yi LENG Yuxin 《等离子体科学和技术》2011,13(1):3-10
Propagation of intense femtosecond laser pulses (60 fs, 800 nm, 120 mJ, 6×1017 W cm-2 in vacuum) in supersonic (CD4)N and (D2)N cluster jets at different background pressures was studied. Pump-probe interferometry is employed to investigate the propagation of laser beams in dense cluster jets by examining the electron density distribution of plasma channels. It was found that propagation effects, including ionization-induced defocusing and laser attenuation of incident pulses, are very different in the (CD4)N and (D2)N cluster jets. Different ionization states of CD4 and D2 molecules were observed by analyzing the transverse electron density profiles of the plasma channels and should be considered as a major reason for the differences in the propagation effects. Numerical simulations of the nonlinear propagation of femtosecond laser pulses in (CD4)N and (D2)N cluster jets were performed, and the results indicated a good reproduction of the experimental data. 相似文献
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A study on the interactions of high intensity (- 10^16 W/cm^2) femtosecond laser pulses with rare gas clusters in a dense jet is performed. Energy absorption by Ar and Xe clusters is measured and it can be as high as 90%. Very energetic ions produced in the laser interaction with a dense cluster jet are detected by time-of-flight spectrometry and the maximum ion energy of Xe is up to 1.3 MeV. The average ion energies are found to increase with increasing cluster size and get saturated gradually. The average ion energies also show a strong directionality and the average ion energy in the direction parallel to the laser polarization vector is 40% higher than that perpendicular to it. The findings are discussed in terms of a model of charge-dependent ion acceleration. 相似文献
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《等离子体科学和技术》2016,18(12):1192-1197
In this paper, we present a study on the effect of inter-pulse delay using femtosecond double-pulse laser-induced breakdown spectroscopy in a collinear geometry. The temporal evolution of spectral intensity is performed for the lines of Fe I 423.60 nm, Fe I 425.08 nm and Fe I 427.18 nm. It is found that, by selecting appropriate inter-pulse delay, the signal enhancement can be significantly increased compared with the single-pulse case. A three-fold enhancement in the current experiment is obtained. The plasma temperature and electron density are also investigated based on the theory of Boltzmann plot and Stark broadening. We attribute the main mechanism for emission enhancement to the plasma re-heating effect. 相似文献
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首次提出了一种新颖的窄脉冲峰值保持方法.其原理是在脉冲激励下形成衰减振荡波,由峰值包络检波后的电流向电容器充电,最终在电容器上保持脉冲峰值信息.该方法解决了保持电容的充电时间常数完全依赖于脉冲宽度的问题.介绍了工作原理,给出了实现电路和实验结果.该电路结构简单、可靠性好,已经在高精度无协作目标激光脉冲测距仪中应用. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(7):671-673
The oxidation of Np(V) by nitrous acid was investigated spectroscopically in 0.2 M CMPO—1.4 M TBP—n-dodecane and the oxidation rate constant of Np(V) was estimated assuming the first-order reaction. By using the obtained oxidation rate constant as well as taking account of the Np(V) oxidation in aqueous phase and the distribution ratios of Np(V) and Np(VI) cited from literature, extraction kinetics of Np from 4 M nitric acid solution was calculated, and was compared with the extraction kinetics measured experimentally. 相似文献
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Considering the limiting weak nonlinearity, we obtained the solution of the coupled equations describing the interaction of ultraintense laser with cold transparent multicomponent plasma. It was indicated that the ions tend to accumulate at the center of the soliton and have large velocity when we consider the mobile ions in the multicomponent plasma, which shows that the result is different from that of the Berezhiani's analysis. The change of proportion of ions in the plasma has effects on the amplitude of vector potential and the maximum velocity of the soliton. 相似文献
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利用15 TW激光脉冲,系统研究了基于电离化注入的激光尾波场加速。实验中,研究了等离子体密度、相互作用位置、激光脉宽以及激光能量对电子束的电荷量、发散角、指向性、能量以及产生概率的影响。将约400 mJ、25 fs的激光脉冲聚焦在喷嘴前沿,等离子体密度约9×1018 cm-3时,电子的产生概率高达100%,获得了水平(竖直)发散角(6.5±0.5) mrad((5.3±0.3) mrad)、水平(竖直)指向稳定性±1.2 mrad (±0.7 mrad)、峰值能量(135±8) MeV和电荷量(13.5±2.0) pC(>50 MeV)的稳定电子束,为其应用奠定了基础。 相似文献
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By using a one-dimensional self-consistent relativistic fluid model, an investigation is made numerically on relativistic electromagnetic solitons with a high intensity in cold overdense plasmas with an electrons' initial velocity opposite to the laser propagating direction. Two types of standing solitons with zero group velocity are found at the given electrons' initial velocities. One is single-humped with a weakly relativistic intensity; the another is multi-humped with a strong relativistic amplitude. The properties of these two types of solitons are presented in detail. 相似文献
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