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强场作用下二能级原子双光子过程中的光子聚束与反聚束效应 总被引:6,自引:3,他引:3
本文采用数值计算方法研究了强场作用下二能级原子双光子过程中的光子聚束与反聚束效应.结果表明:辐射光子主要表现为反聚束性质,且随着n值的不断增大,场与原子的非线性耦合越来越强,重复地出现复苏收缩现象和短时的光子聚束效应. 相似文献
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研究了利用原子玻色-爱因斯坦凝聚体与制备的原子激光的二阶相干性质. 结果表明,这种原子激光是反聚束的,在一定条件下,是二阶相干的. 相似文献
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基于半经典理论,分析了中性钠原子在激光驻波场中的受力特征,以此为基础分别对不同纵向运动速度和横向运动速度条件下中性钠原子的运动轨迹进行了仿真运算,得到了不同速度条件下中性钠原子的运动轨迹特征,基于累计算法进一步对不同速度条件下中性钠原子的沉积特性进行了仿真,当钠原子的纵向运动速度符合最可及速度(740 m/s)时,纳米沉积条纹的半高宽为2.78 nm,条纹对比度为38.5 ∶1,当纵向运动速度偏离最可及速度(350 m/s)时,纳米沉积条纹的半高宽为29.1 nm,其对比度下降为15 ∶1.而当中性钠原子
关键词:
原子光刻
激光驻波场
条纹半高宽
条纹对比度 相似文献
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利用受激Raman跃迁制备的原子激光的相干性 总被引:1,自引:1,他引:0
研究了利用原子玻色-爱因斯坦凝聚体与光相互作用产生受激Raman跃迁制备的原子激光二阶相干性质。结果表明,这种原子激光是反聚束的,在一定条件下,是二阶相干的。 相似文献
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从双色激光场中运动原子的受激跃迁速率和激光场对原子的辐射压力关系出发,讨论了运动原子在驻波场中速度聚集效应产和珠原因及其与多光子过程的关系,给出了聚速效应出现的条件,预言了极值聚速速度的存在,通过简单的,变换,将驻波场原五速度聚集效应的相结论推广至双色激光场。 相似文献
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利用近共振激光驻波场操纵中性原子实现纳米光栅的沉积是一种新型的研制纳米结构方法,处于激光驻波场中的原子运动速度特性对最终纳米光栅的沉积特性有着重要的影响.利用半经典理论,基于4阶Runge-Kutta算法进行了不同铬原子纵向和横向运动速度条件下纳米光栅结构沉积的仿真研究.研究表明,铬原子纵向速度为最大概率速度960 m/s时,所形成的纳米光栅的半高宽为1.49 nm,对比度为62.1 ∶1,当铬原子的纵向速度为半最大概率速度480 m/s时,纳米光栅的半高宽为5.35 nm,对比度下降为25.6 ∶1.同
关键词:
原子光刻
纳米计量
激光驻波场
纳米光栅结构 相似文献
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单频漫射光对原子的冷却与单色效应 总被引:1,自引:1,他引:0
计算了用单频漫射光作用于一个两能级原子产生的幅射压力,数值计算了辐射压力对原子速度分布的影响,并讨论其单色性,结果表明,采用这种机制冷却原子束,不仅能实现高效率的激光冷却,而且可以获得速度宽度小于8m/s的近单色原子。 相似文献
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双模光场与运动三能级原子作用系统的反聚束效应 总被引:5,自引:0,他引:5
采用求解Schrdinger方程和数值计算方法,研究了双模纠缠相干光场与运动V型三能级原子相互作用过程中的聚束和反聚束效应.结果表明:平均光子数变动不大,系统就会由聚束效应跃变为反聚束效应,关联程度最强;平均光子数取一定数值时,原子运动速度增大引起时间演化曲线显著上移,振荡周期变小,对系统的聚束和反聚束效应也有较强影响.当平均光子数较大时,原子初态和双模纠缠相干光场的纠缠度无任何影响;仅当平均光子数较小时,原子初态和双模纠缠相干光场的纠缠度变化引起曲线振荡幅度变化,位置发生小幅度移动,产生弱关联. 相似文献
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The modern approach to designing an injector for the driver of a two-beam accelerator is based on the use of a bunched electron
beam. The results of simulation and comparison of the processes leading to bunching of a relativistic electron beam in a free-electron
laser and in a traveling-wave tube at low electron beam energies are discussed. The simulation and existing experimental results
for bunching of an electron beam in a free-electron laser are compared.
Zh. Tekh. Fiz. 69, 98–102 (February 1999) 相似文献
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《等离子体物理论文集》2017,57(4):167-175
In this article, we report the generation of terahertz (THz) radiation using the interaction of a laser‐modulated relativistic electron beam (REB) with a surface plasma wave. Two laser beams propagating through the modulator interact with the REB, leading to velocity modulation of the beam. This results in pre‐bunching of the REB. The pre‐bunched beam travels through the drift space, where the velocity modulation translates into density modulation. The density‐modulated beam, on interacting with the surface plasma pump wave, acquires an oscillatory velocity that couples with the modulated beam density to give rise to a nonlinear current density which acts as an antenna to give THz radiation. By optimizing the parameters of the beam and the wiggler, we obtain power of the order of 10−4 using the current scheme. 相似文献
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Hendrickson S. Cary J.R. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1996,24(2):439-442
An adiabatic free-electron laser wiggler for electron beam bunching is described. A free-electron laser naturally bunches an electron beam. When the beam is trapped adiabatically, the emittance of the bunched beam is decreased significantly compared with abrupt trapping. For a 57-period two-meter buncher having poleface magnetic field of 2 T and 10 GW of 100 μm radiation, adiabatic trapping reduces the final emittance by a factor of three 相似文献
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The interaction of free electrons and free electromagnetic radiation, in the presence of a uniform magnetic field, can result
in stimulated emission or absorption. We analyze the dynamics of single electrons by solving the classical, relativistic Lorentz
force equations of motion in these combined fields. An electron may gain energy from, or lose energy to, the radiation field,
depending crucially on the phase and oscillation frequency of the electron's helical motion within the superposed, circularly
polarized light wave. To first order in the radiation field strength, electrons in a monoenergetic, uniformly distributed
beam become spatially bunched, but there is no net energy change. To second order, however, the beam may experience a gain
or loss of energy, corresponding to attenuation or amplification of radiation. We compare the bunching of this laser process
to the bunching processes involved in 1) the Stanford free-electron laser and 2) the cyclotron maser, and find significant
differences in each case. Our analytic results provide a clear, simple picture of the interaction process, and can be useful
in exploring light amplification in astrophysical magnetic fields, the magnetosphere, or in laboratory devices.
Supported in part by Army Contract No. DASG 60-77-C-0083 and NASA Grant NSG-7490. 相似文献
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从理论上计算了原子在球面波场中的受力情况,提出具体球面波磁光阱(MOT)的方案,计算结果表明,球面波冷却和捕陷原子的方法具有冷却原子的范围大和捕陷原子的数目多,冷却效率高等优点。并可极大地缩小装置的体积。 相似文献
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The step structure transition between a regular step and a bunched step on vicinal Si(1 1 1) surfaces induced by DC is studied by the kinetic Monte Carlo simulation in a terrace-adatom-step-kink (TASK) model. In the TASK model, effective force due to DC is taken into account explicitly on the mass transport of Si adatoms. In the diffusion-limited regime corresponding to the experimental temperature range II, step bunching is induced by step-up force and in-phase wandering of a regular step is formed by step-down force. The in-phase wandering of a regular step is formed by nucleation growth mode and the amplitude of wandering grows with time in proportion to
. The period of in-phase wandering decreases as the effective force increases, consistent with the recent experimental results. 相似文献
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U. Schramm M. Bussmann D. Habs M. Steck T. Kühl K. Beckert P. Beller B. Franzke F. Nolden G. Saathoff S. Reinhardt S. Karpuk 《Hyperfine Interactions》2005,162(1-4):181-188
We report on the first laser cooling of a bunched beam of multiply charged ions performed at the ESR (GSI) at a beam energy of GeV. Moderate bunching provided a force counteracting the decelerating laser force of one counterpropagating laser beam.
This versatile type of laser cooling lead to longitudinally space-charge dominated beams with an unprecedented momentum spread
of . Concerning the beam energy and charge state of the ion, the experiment depicts an important intermediate step from the established
field of laser cooling of ion beams at low energies toward the unique laser cooling scheme proposed for relativistic beams
of highly charged heavy ions at SIS 300 (FAIR).
Funded by the German BMBF under contract number 06ML183. 相似文献
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The interaction of ultrashort intense circularly polarized laser with ultra thin overdense foil is studied by particle-in-cell simulation and analytic model. It is found that with the balance between pondermotive force and electrostatic force, highly quasi-monoenergetic proton beam can be generated by Phase Stable 相似文献
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LIU Bi-Cheng YAN Xue-Qing LIN Chen Lu Yuan-Rong GUO Zhi-Yu FANG Jia-Xun SHENG Zheng-Ming LI Yu-Tong CHEN Jia-Er 《中国物理C(英文版)》2009,33(Z2)
The interaction of ultrashort intense circularly polarized laser with ultra thin overdense foil is studied by particle-in-cell simulation and analytic model.It is found that with the balance between pondermotive force and electrostatic force,highly quasi-monoenergetic proton beam can be generated by Phase Stable Acceleration(PSA)process.As in conventional accelerators,ion will be accelerated and bunched up in the longitudinal direction at the same time. 相似文献