共查询到19条相似文献,搜索用时 156 毫秒
1.
本文从广义协变的运动方程和麦克斯韦方程出发,导出了电子等离子体波各量的解析表达式。指出△ω=2ωp的等离子体波是完全简谐的。完全共振的条件由△ω=2ω(p0)[1+(e2(A2((1)2)+(A2((2)2))/(2m2c4)+(3e2A2(1)A2(2))/(m2c4)]-1/2 给出。
关键词: 相似文献
2.
本文应用动力学方法计算了均匀非磁化等离子体的电子二级非线性密度涨落,得到了三波在等离子体中相互作用的三级非线性极化率X(3)和第四波K4=K1-K2+K3,ω4=ω1-ω2+ω3的散射功率,与通常的非相干汤姆逊散射相比,其散射信号要大得多,因此,相干四光子散射可以作为等离子体诊断技术的一个重要方法,本文还指出,文献[4]的结果是本文计算的一个简单情况。
关键词: 相似文献
3.
4.
我们用缀饰模型研究强近共振激光脉冲驱动下二能级系统与弱试探脉冲的相互作用。当试探脉冲的频率ω2调到共振频率ω2=ω1±<Ω21D>时,试探脉冲呈现吸收或放大效应。还得到非线性混频效应的瞬态过程。共振增强存在于此非线性混频过程中。
关键词: 相似文献
5.
电子俘获是激光尾波场加速电子的主要机理,增大电子的初速度可以使更多的电子被尾波场俘获.提出三角脉冲激发尾波加速电子的方案,三角脉冲平缓上升沿激发受激Raman散射,用以初步加速电子,三角脉冲陡峭下降沿激发尾波场,将更多的电子加速到接近光速.2D3V粒子模拟结果证实了这一点.同时表明:脉冲长度为几个等离子体波长的超强激光在稀薄等离子体中传播时,还激发侧向Raman散射.在侧向受激Raman散射中,静电波增长最快的波矢模式为kp=(2ωp/ω0
关键词:
有质动力
电子俘获
前向受激Raman散射
侧向受激Raman散射 相似文献
6.
7.
8.
9.
10.
11.
Non-degenerate four-wave mixing using two non-collinear laser beams with frequencies (wavevectors) ωp, ωt (kp, kt) respectively is studied in CuCl. Two emission lines at frequencies ω(1)=2ωt-ωp, and ω(2)=2ωp-ωt are observed. Their excitation spectrum is sharply peaked if the phase-match condition k(1)=2kt-kp is fulfilled. This is the case, if ωp coincides with the hyper-Raman lines (R+T, R-T) of the laser labelled (t) in a well-defined geometrical configuration. 相似文献
12.
Yu. E. Lozovik S. P. Merkulova M. M. Nazarov A. P. Shkurinov P. Masselin 《JETP Letters》2002,75(9):461-464
A new surface-sensitive method of time-resolved optical studies is proposed. The method consists in the independent excitation of several surface electromagnetic waves (SEW) by two laser femtosecond pulse beams with varied time delay Δτ and distance Δr between corresponding excitation regions on the surface. To fulfill the phase-matching condition for plasmon-photon coupling, metal grating is used. Due to nonlinear plasmon interaction, the optical radiation with ω1 + ω2 and 2ω1 ? ω2 (where ω1, ω2 are corresponding laser beam frequencies) is generated. The intensity of this nonlinear response versus Δτ and Δr are studied. The direct measurements of the SEW temporal properties are presented. Experiments of this type are important for the development of femtosecond surface plasmon optics. 相似文献
13.
The dispersion characteristics of a plasma in a pump field ??(t) = ?? sub ω0t + ??1 sin ω1t are considered. Firstly we assume, that the second wave is weak (|??1| ? |??0|) and the frequency ω1 is near sω0(ω1 = sω0 + Ω,Ω ? ω0). We obtain the dispersion equation, describing the parametric coupling of the waves driven by the strong field ??0 sin ω0t under the resonance condition ω0 ≈ ωLe/P and derive the expressions for the growth rates (ωLe is the electron LANGMUIR frequency; s, p are integers). In the second part it is shown, that a strong field ??1 with a frequency ω1 much larger than ω Le(ω Le ≈ pω0) stabilizes the plasma; the growth rates are reduced and the frequency region of the parametric instability is contracted. 相似文献
14.
Hans Haldemann 《Applied Physics A: Materials Science & Processing》1974,3(4):291-298
Parametric traveling-wave interactions are calculated with the aid of a plane wave approximation, considering the 4 frequencies ω s , ω p , ω I =ω p ?ω s and ω Σ =ω p +ω s . Special attention is paid to the case where ω p ?ω s . Competition between parametric amplification and upconversion is studied as a function of phase matching and the results are illustrated by means of numerical examples. It is shown that parametric gain disappears if the linear combination of wave vectors, 2k p-kI-kΣ, vanishes. In this situation upconversion with power gain up to about (ω Σ /ω s )2 is possible. It is concluded that fork p?ks the sum frequency ω Σ can significantly influence parametric forward amplification but does not affect backward wave amplification. 相似文献
15.
In the frame work of TREDER 's gravitational theory we consider two classes of field equations which are derivable from two classes of LAGRANGE ian densities Ω(1)(ω1, ω2), Ω(2)(s?1, s?2). ω1, ω2; s?1, s?2 are parameters. Ω(2)(ω1, ω2) gives us field equations which are up to the post-NEWTON ian approximation in the sense of NORDTVEDT , THORNE and WILL equivalent to the field equations given by BRANS and DICKE . For ω2 = ?1 ?2ω1 field equations follow from Ω(1)(ω1, ?1 ?2ω1) which are in the above mentioned sense of post-NEWTON ian approximation equivalent to EINSTEIN 's equations. The field equations following from Ω(1)(ω1, ω2) have a cosmological model with the well known cosmological singularities for T → ± ∞ in case that ω1/(1 +3ω1 +ω2) ? γ > 0. For ω1/(1 +3ω1 +ω2) ≤ 0 cosmological models with no cosmological singularities exist. From Ω(2)(s?1, s?2) we obtain field equations which at the best give us perihelion rotation 7% above EINSTEIN 's value and light deflection 7% below the corresponding EINSTEIN 's value. But in that case we are able to show the existence of a cosmological model without any cosmological singularity. 相似文献
16.
Abstract In this paper, the authors have derived the expression for the combination frequency components ω3 = 2ω1-ω2 in the current density by solving the appropriate Boltzmann transfer equation for electrons, when two laser beams of frequencies of ω1 and ω2 are incident on a degenerate nonparabolic semiconductor viz. InSb; the nonlinearity due to collision mechanism as well as the nonparabolicity of conduction band has been taken into account. The ionized impurity scattering has been considered to be the sole mechanism of electron scattering. The expression for the current density is further substituted in the wave equation to obtain the expression for the amplitude of combination frequency wave in the transmitted component. The calculated value of output power of frequency ω2 is found to be 1/10th of the experimental value (Patel, Slusher and Fleury, 1966), (7) and thus is in better agreement as compared to earlier investigators (Wolff and Pearson, 1966; Kaw, 1968). (5, 10) 相似文献
17.
R. A. Ganeev A. I. Ryasnyanskiĭ M. K. Kodirov T. Usmanov 《Optics and Spectroscopy》2001,91(6):878-882
Results of theoretical studies of laser and Kerr nonlinear susceptibilities of vapors and solutions of organic dyes using a series of polycyclic arenes as an example are presented. Nonlinear susceptibilities of the third χ(3) (?3ω; ω, ω, ω) and the fifth χ(5) (?3ω; ω, ω, ω, ω, ?ω) orders of a series of organic dyes responsible for third harmonic generation of Nd:YAG laser radiation are calculated within the context of the free electron model. Results of calculations of their Kerr third-order nonlinear susceptibilities χ(3) (?ω; ω, ?ω, ω) and non-linear refractive indices n 2 are presented. The calculation results are compared with experimental data on third harmonic generation in naphthalene vapors and with χ(3) (?ω; ω, ?ω, ω) as well as n 2 of paraterphenyl and naphthalene solutions. 相似文献
18.
讨论了垂直入射的、频率为ωg的平面高频引力波对环形波导管中频率为ωe的电磁波的调制作用.一般情况下,在波导管中与引力波传播方向垂直的对称平面附近,电磁波的能流密度会出现三种新的频率成分(2ωe±ωg)和ωg.在ωg》ωe时,能流密度振幅的相对调制量与引力波的无量纲振幅h0数量级相同.特别是当ωg,ωe和电磁波绕波导传播的绕行频率ω0满足关系ωg=2ωe》ω0时,由于类似于共振的机制,能流密度会出现比h0大几个数量级的振幅相对调制量.这个结果不会由于参数的微小改变而消失,这对于探测极微弱的引力辐射信号将是十分重要的
关键词: 相似文献
19.
The a.c. conductivity σ(ω) of ionic materials takes the form, σ(ω) = σ(0) + Aωn. The carrier hopping rate, ωp, is obtained from the new expression σ(0) = A ωpn and the carrier concentration is estimated from σ(0). The contribution of creation and migration terms to the activation energy for conduction may be determined from the thermal activation of σ(0) and ωp and the corresponding entropy terms quantified. Data have been analyzed for four widely different ionic materials: single crystal Na β-alumina, polycrystalline Li4SiO4, Ag7l4AsO4 glass and Ca(NO3)2/KNO3 glass and melt. For each, the carrier concentration and hopping rates have been obtained. 相似文献