共查询到19条相似文献,搜索用时 265 毫秒
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利用皮秒和飞秒激光研究了激光在空气中聚焦产生单个等离子体通道的条件.研究发现,能量为8—12mJ皮秒激光被焦距为15cm的透镜聚焦后,可以产生较为稳定的单个通道.通过横向纵向阴影成像分析发现,通道的管壁对聚焦产生的自发光具有箍缩作用,而通道内部却有利于光的传输.同时还发现,当采用短焦距透镜时,能量低于10mJ的飞秒激光在空气中较易形成单个等离子通道.
关键词:
等离子体通道
皮秒激光
飞秒激光
阴影成像 相似文献
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为了研究多光子非线性Compton散射对飞秒激光退吸附作用对等离子体通道寿命的影响,应用多光子非线性Compton散射模型和强飞秒激光在空气中产生等离子体通道内带电粒子动力学模型,提出了多光子非线性Compton散射是影响等离子体辐射阻尼和通道寿命的一个重要机制,给出了等离子体通道中带电粒子的修正动力学方程,并进行了数值计算和实验研究.结果表明:散射削弱了自由电子对氧分子的吸附和正负离子的复合,有效地补偿了等离子体的辐射阻尼效应,后续激光脉宽和间隔以及Compton散射是影响等离子体辐射阻尼和通道寿命的关键因素,理论计算与实验结果较好的吻合. 相似文献
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为了研究多光子非线性Compton散射对飞秒激光退吸附作用对等离子体通道寿命的影响,应用多光子非线性Compton散射模型和强飞秒激光在空气中产生等离子体通道内带电粒子动力学模型,提出了多光子非线性Compton散射是影响等离子体辐射阻尼和通道寿命的一个重要机制,给出了等离子体通道中带电粒子的修正动力学方程,并进行了数值计算和实验研究。结果表明:散射削弱了自由电子对氧分子的吸附和正负离子的复合,有效地补偿了等离子体的辐射阻尼效应,后续激光脉宽和间隔以及Compton散射是影响等离子体辐射阻尼和通道寿命的关键因素,理论计算与实验结果较好的吻合。 相似文献
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超短脉冲激光在引导闪电中的应用 总被引:1,自引:0,他引:1
超短超强激光可以在大气中引起非线性效应以及产生等离子体,超短超强激光在非线性自聚焦和等离子体散焦的平衡可以使激光在大气中传播很长的距离,从而产生一条较长的低密度的等离子体通道,文章对其形成的原理和利用其引导闪电的可行性进行阐述,说明该通道在外场下可以触发和引导闪电到安全地点,对其机制的深入研究对工业和国防应用具有重要的意义。 相似文献
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The propagation characteristics of an intense laser beam in a preformed plasma channel with the flat-bottom leaky density profile are investigated in detail. The evolution equation of the laser spot size is derived by employing variational technique. Seven propagation modes of the laser spot size are identified and some numerical results are presented. By comparison, we find that the results in this Letter may be more realistic since the flat-bottom leaky plasma channel comes closer to the practical plasma channel. 相似文献
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V. V. Borovkov K. I. Almazova E. P. Volkov V. G. Kornilov C. Yu. Kornilov V. D. Selemir D. A. Tolshmyakov A. A. Khizhnyakov V. I. Chelpanov 《Technical Physics》2003,48(4):415-420
A plasma injector with pulsed gas filling is investigated experimentally. Interferometric measurements of the formation dynamics
of the plasma channel are carried out. Under optimal operating conditions, the injector is capable of producing a plasma channel
4 cm in diameter with an electron density of ∼1017 cm−3. The effect of the cathode diameter of the plasma opening switch on the conductivity of the plasma channel is studied. It
is shown that the current flowing through the plasma channel of a single injector attains 400 kA. 相似文献
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在考虑相对论和有质动力非线性以及全局电量守衡的前提下,分析了强激光在冷等离子体窄通道中稳定传播的情况。采用较为简化的二维理论模型,给出了描述激光和通道横向结构的解,对不同通道宽度、通道密度、激光强度和电磁模式等进行了讨论,分析了其对激光在等离子体通道中传播的影响。分析发现,在存在预通道的情况下,当等离子体通道的密度大于临界密度很多时(例如20倍临界密度),即使是在激光波长量级的通道中,激光仍然可以传播。通道越宽,等离子体密度越小;激光强度越大越容易传播。在同样的通道和传输情况下,TE0模传输所需要的激光强度比TE1模要小。 相似文献
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《Current Applied Physics》2014,14(3):287-293
Lumped parameter models for describing dynamics of the plasma channel in a parallel-plate plasma gun are compared with the experimental results obtained from two plasma guns with different rail geometries. Comparison between the experiments and the numerical calculations reveals that the lumped parameter models can be utilized to describe the dynamic motion of the plasma channel quite well. Parametric study shows that minimizing the line inductance and increasing the charging voltage on a capacitor as well as minimizing the gas injection time for reducing the mass of the plasma channel are the key factors to increase the flow velocity of the plasma jet ejected from the plasma gun. 相似文献
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Gonsalves AJ Rowlands-Rees TP Broks BH van der Mullen JJ Hooker SM 《Physical review letters》2007,98(2):025002
Transverse interferometric measurements are presented of the plasma channel formed in a hydrogen-filled capillary discharge waveguide recently used to generate 1 GeV electrons in a laser-driven plasma accelerator for the first time. The measurements were found to be in good agreement with nonlocal thermal equilibrium simulations, but showed significant differences with the results of a quasistatic model developed by Bobrova et al. [Phys. Rev. E. 65, 016407 (2001)]. The measurements are used to determine scaling laws for the axial electron density and matched spot size of the plasma channel, enabling optimization of the channel to specific applications. 相似文献
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S. V. Bobashev B. G. Zhukov R. A. Kurakin S. A. Ponyaev B. I. Reznikov S. I. Rozov 《Technical Physics》2010,55(12):1754-1759
The working current dependences of the thermodynamic and electrophysical parameters of a free plasma piston moving with a
near-maximal velocity in the channel of an electromagnetic rail launcher with graphite electrodes are obtained. The composition
and weight of the plasma depend on the degree of electrode erosion due to discharge current passage (i = 40–80 kA). It is shown that the mean temperature of the plasma piston only slightly depends on the plasma mean pressure
and plasma piston weight and increases with current by a near-power law. The measured values of the maximal velocity of the
plasma piston front are compared with the calculated value of the sound velocity inside the piston. With the working current
and cross-sectional area of the channel fixed, the initial gas density in the channel is found to influence the ratio of the
piston maximal velocity to the sound velocity in the plasma. If the initial gas density is low (lower than some critical value),
the maximal velocity of the plasma piston front exceeds the sound velocity in the plasma. 相似文献
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Naveen Gupta 《等离子体物理论文集》2019,59(2):154-165
This paper presents a theoretical investigation of the propagation characteristics of a q‐Gaussian laser beam propagating through a plasma channel created by the ignitor‐heater technique. The ignitor beam creates the plasma by tunnel‐ionization of air. The heater beam heats the plasma electrons and establishes a parabolic channel. The third beam (q‐Gaussian beam) is guided in the plasma channel under the combined effects of density non‐uniformity and non‐uniform ohmic heating of the plasma channel. Numerical solutions of the non‐linear Schrodinger wave equation (NSWE) for the fields of laser beams are obtained with the help of the moment theory approach. Particular emphasis is placed on the dynamical variations of the spot size of the laser beams and the longitudinal phase shift of the guided beam with the distance of propagation. 相似文献