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飞秒激光多脉冲烧蚀镍钛合金的数值模拟 总被引:1,自引:0,他引:1
为了研究飞秒激光多脉冲累积效应对镍钛合金材料的影响,通过考虑多脉冲之间的时间间隔改写激光光源项,利用改进的双温模型,采用有限差分法,对飞秒激光三脉冲烧蚀镍钛合金的温度场分布进行数值模拟,得到了电子和晶格温度随时间和烧蚀深度的演化规律.分析了多脉冲累积效应的内在机理;讨论了三脉冲条件下不同参量对电子和晶格温度的影响.结果表明:镍钛合金在飞秒激光三脉冲的作用下,电子有3个递增的峰值温度,相比单脉冲的作用,三脉冲使电子和晶格温度明显升高;多脉冲的时间间隔直接影响多脉冲的累积效应;脉冲宽度影响电子的峰值温度和达到峰值温度所用的时间;激光能量密度影响电子和晶格的温度;电声耦合常量对电子与晶格的耦合时间和电子晶格的平衡温度也有重要影响. 相似文献
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通过求解电子运动的相对论方程,发现预加速电子在超强超短激光脉冲的作用下可以获得很高的能量增益. 飞秒激光脉冲的上升沿在焦点附近的区域有效加速电子后,电子和光脉冲一起传播一段距离(远大于瑞利长度)后,激光强度变得很弱,从而使脉冲下降沿对电子的减速作用可以忽略不计,因此电子只经历加速过程而没有被减速,当电子和光脉冲分离时,电子获得了很高的能量增益. 当光强为1019W/cm2 ,电子的初始能量为MeV量级时,电子的能量增益可以达到01GeV. 进一步讨论了电子的能量增益与电子的初始条件与激光脉冲的参数之间的关系.
关键词:
电子加速
飞秒激光脉冲
能量增益 相似文献
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为研究激光脉冲能量对激光诱导等离子体辐射特性和膨胀过程的影响,采用ICCD相机对不同激光脉冲能量激发的铝合金等离子体进行快速成像,并利用Boltzmann斜线法和Stark展宽法分析等离子体的电子温度和电子数密度随激光脉冲能量的演化规律.实验结果表明,激光诱导等离子体呈现明显的分层结构,等离子体的激发阈值约为3mJ,等离子体不同区域的面积随激光脉冲能量变化呈现不同的特征.当激光脉冲能量低于10mJ时,等离子体的分层结构不显著.激光脉冲能量从10mJ增加到100mJ过程中,等离子体电子温度从4 980K升高到7 221K,等离子体的电子数密度在1017 cm-3量级并随激光能量增加而增大且趋于饱和. 相似文献
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随着超短脉冲激光技术的发展, 人们可以在台面尺度获得光强超过1018W/cm2、脉宽小于100fs的超短脉冲激光.超短脉冲激光很容易把静止的电子加速到兆电子伏的能量. 而更重要的是超短激光脉冲可以通过其有质动力激发大振幅的等离子体波(称为激光尾波场), 后者可以在毫米空间尺度把电子加速到上百兆电子伏的能量.文章将介绍激光尾波场加速电子的物理机制和方案、这个领域的最新进展、以及目前存在的问题. 相似文献
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研究了超短超强激光脉冲与薄膜靶相互作用中产生的电子热发射.当超短激光脉冲与薄膜靶相互作用时,首先入射超短脉冲激光对吸收深度内的自由电子进行热激发,接下来热激发电子将能量传递到附近的晶格,再通过电子和晶格二体系的热传导,以及电子晶格间的热耦合,将能量传递到材料的内部.因此,电子在皮秒级甚至更短的时间内不能与晶格进行能量耦合,使电子温度超出晶格温度很多,电子热发射就变得非常明显了.用双温方程联合Richardson-Dushman方程的方法对飞秒脉冲激光照射金属靶的电子热发射进行了研究,结果发现电子热发射对飞 相似文献
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Oscar Buneman 《Physics letters. A》1985,108(7):351-352
A self-consistent model for an electron pulse propagating through a plasma is presented. In this model, the charge imbalance between plasma ions, plasma electrons and pulse electrons creates the travelling potential well in which the pulse electrons are trapped. 相似文献
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A numerical experiment in which two relativistically intense laser pulses are normally incident on a layer of a diluted plasma
from two opposite sides is described. The period of Langmuir plasma oscillations is much larger than the pulse duration and
the product of this period by the speed of light is much larger than the thickness of the layer. A pulse propagating to the
right is incident on the layer earlier than the counter pulse and carries a significant fraction of electrons or all of the
electrons from the plasma. Under certain conditions, electrons form a bunch, which contains most of the electrons and has
a thickness much smaller than the wavelength of light. The counter pulse perturbs the motion of the bunch and initiates the
emission of a short few-cycle pulse, which propagates in the positive direction (to the right), significantly differs in structure
from the counter pulse, and has a duration much smaller than the field period in laser pulses. 相似文献
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We propose a new approach to high‐intensity relativistic laser‐driven electron acceleration in a plasma. Here, we demonstrate that a plasma wave generated by a stimulated forward‐scattering of an incident laser pulse can be in the longest acceleration phase with injected relativistic beam electrons. This is why the plasma wave has the maximum amplification coefficient which is determined by the acceleration time and the breakdown (overturn) electric field in which the acceleration of the injected beam electrons occurs. We must note that for the longest acceleration phase the relativity of the injected beam electrons plays a crucial role in our scheme. We estimate qualitatively the acceleration parameters of relativistic electrons in the field of a plasma wave generated at the stimulated forward‐scattering of a high‐intensity laser pulse in a plasma. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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E. H. Baksht I. D. Kostyrya E. I. Lipatov M. I. Lomaev D. V. Rybka V. F. Tarasenko 《Technical Physics》2007,52(4):489-494
The characteristics of an IMA3-150É sealed-off vacuum diode connected to a RADAN-220 nanosecond pulser are investigated. It is found that the electron beam behind the foil contains electrons with an energy exceeding the voltage applied to the diode. It is shown that the elevated-energy electrons appear at the leading edge of a current pulse, the FWHM of the current pulse of these electrons is 200–450 ps, and the pulse amplitude reaches several tens of amperes. 相似文献
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A method for enhancing trapped electrons in the laser wake-field acceleration in dilute plasma is proposed. In this method, a thin layer with near critical density is placed in front of the dilute plasma. Upon interaction of this layer with a short and high power laser pulse, a relatively large number of layer electrons are injected in dilute plasma. Some of these electrons are trapped in the wake-field of transmitted laser pulse. Particle in cell simulation is used to demonstrate this method. Simulations showed that in addition to increasing the number of trapped electrons, this mechanism also reduces the energy broadening. 相似文献
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Schwoerer H Liesfeld B Schlenvoigt HP Amthor KU Sauerbrey R 《Physical review letters》2006,96(1):014802
We present the first observation of Thomson-backscattered light from laser-accelerated electrons. In a compact, all-optical setup, the "photon collider," a high-intensity laser pulse is focused into a pulsed He gas jet and accelerates electrons to relativistic energies. A counterpropagating laser probe pulse is scattered from these high-energy electrons, and the backscattered x-ray photons are spectrally analyzed. This experiment demonstrates a novel source of directed ultrashort x-ray pulses and additionally allows for time-resolved spectroscopy of the laser acceleration of electrons. 相似文献
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Wetzels A Gürtler A Noordam LD Robicheaux F Dinu C Muller HG Vrakking MJ van der Zande WJ 《Physical review letters》2002,89(27):273003
The asymptotic velocity distribution of electrons ionized in half-cycle-pulse excitation of high Rydberg states (n=34), placed in a static electric field, is studied using electron velocity-map imaging. At weak half-cycle pulse strengths, the electrons escape over the saddle point in the potential. For strong half-cycle pulses, the electrons are emitted in the direction of the field kick. The much slower and less intense half cycle of opposite polarity, which necessarily follows the main half-cycle pulse, strongly affects the momentum distribution and reduces the excess energy of the electrons significantly. 相似文献