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Effective response in nonlinear spherical coated composites under external AC and DC electric fields
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By using the perturbation method,effective nonlinear direct current(DC) and alternating current(AC) responses of nonlinear composites with spherical coated inclusions randomly embedded in a host medium are studied under the action of an external electric field E a = E 0 + E 1 sin ωt + E 3 sin 3ωt with different amplitudes and frequencies.The local potentials of composites at all harmonics are given in the inclusion particles and the host regions.All effective nonlinear responses to composites and the relationship between the effective nonlinear responses at all harmonics are also deduced for the spherical coated inclusions in a dilute limit. 相似文献
3.
An effective nonlinear response of a nonlinear composite
with spherical coated inclusions randomly embedded in a host medium
under the action of an external AC electric field, {{\bm E}}_a =
{{\bm E}}_1 \sin (\omega t) + {{\bm E}}_3 \sin (3\omega t), is
investigated using a perturbation method. The local potentials of the
composite at higher harmonics are given both in the region of local
inclusion particles and in the local host region under the external
AC electric field. All effective nonlinear responses of the composite
and the relationship between the effective nonlinear responses at
the fundamental frequency and third harmonics are also studied for
spherical coated inclusion in a dilute limit. 相似文献
4.
5.
Electric field distribution and effective nonlinear AC and DC responses of graded cylindrical composites
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The perturbation method is used to study the localization of electric field distribution and the effective nonlinear response of graded composites under an external alternating-current (AC) and direct-current (DC) electric field Eapp = E0 (1+sin ωt). The dielectric profile of the cylindrical inclusions is modeled by function εi (r) = Ck rk (r ≤ a), where r is the radius of the cylindrical inclusion, and Ck, k, a are parameters. In the dilute limit, the local potentials and the effective nonlinear responses at all harmonics are derived. Meanwhile, the general effective nonlinear responses are also derived and compared with the effective nonlinear responses at harmonics under the AC and DC external field. It is found that the effective nonlinear AC and DC responses at harmonics can be calculated by those of the general effective nonlinear of the graded composites under the external DC electric field. Moreover, the obtained local electrical fields show that the electrical field distribution in the cylindrical inclusions is controllable, and the maximum of the electric field inside the cylinder is at its center. 相似文献
6.
Effective response of nonlinear cylindrical coated composites under external AC and DC electric field
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This paper uses the perturbation method to study effective response
of nonlinear cylindrical coated composites. Under the external AC
and DC electric field Ea(1 + sinωt), the
local potentials of composites at all harmonic frequencies are
induced. An effective nonlinear response to composite is given for
the cylindrical coated inclusions in the dilute limit. 相似文献
7.
Effective AC Response of Nonlinear Spherical Coated Composites 总被引:2,自引:0,他引:2
Under alternating current electric field, effective response of granular nonlinear composites with spherical coated inclusions is investigated in the dilute limit by using the perturbation approach. For an external sinusoidal applied field with finite
frequency ω, the local fields and potentials of composites in
general consist of components at all harmonics for cubic nonlinear
constitutive relationships. We derive the local potentials
of spherical coated composites at harmonics. Moreover, we
give the formulae of the nonlinear effective AC susceptibility
at the third harmonic frequency. 相似文献
8.
A method for determining effective dielectric responses of Kerr-like coated nonlinear composites under the alternating current (AC) electric field is proposed by using perturbation approach. As an example, we have investigated the composite with coated cylindrical inclusions randomly embedded in a host under an external sinusoidal field with finite frequency ω. The local field and potential of composites in general consists of components with all harmonic frequencies. The effective nonlinear AC responses at all harmonics are induced by the coated nonlinear composites because of the nonlinear constitutive relation. Moreover, we have derived the formulae of effective nonlinear AC responses at the fundamental frequency and the third harmonic in the dilute limit. 相似文献
9.
LIU Ye LI Zhi 《理论物理通讯》2008,49(1):231-234
For higher concentration of inclusions, an effective medium approximation (EMA) method is used to investigate the bulk effective response of weakly nonlinear composites, which are subject to the constitutive relation of electric displacement and electric field, Dα = εαE +Xα|E|^2 E. As an example of three dimensions, under the external AC and DC electric fields Eapp = Eα(1 + sinωt), we have derived the general effective nonh'near response of composites by the EMA method for higher concentration of spherical inclusions. Furthermore, the effective nonlinear responses at harmonics are predicted. 相似文献
10.
LIU Ye LIANG Fang-Chu SHEN Hong-Liang 《理论物理通讯》2005,44(4):731-734
A perturbation method is used to study effective response of nonlinear Kerr composites, which are subject to the constitutive relation of electric displacement and electric field, Dα=εαE+xα|E|^2E. Under the external AG and DC electric field Eapp = Eα(1 + sinωt), the effective nonlinear responses and local potentials are induced by the cubic nonlinearity of Kerr materials at all harmonics. As an example in three dimensions, we have investigated this kind of nonlinear composites with spherical inclusions embedded in a host. At all harmonic frequencies, the potentials in inclusion and host regions are derived. Furthermore, the formulae of the effective linear and nonlinear responses are given in the dilute Iimit. 相似文献
11.
SHEN Yu-Yan CHEN Xiao-Gang LI Qian-Qian CUI Wei HAO Yan-Hua 《理论物理通讯》2009,51(4):743-747
Under the external AC and DC electric field, the effective response of nonlinear spherical coated composites, which obey the constitutive relation of electric displacement and electric field, is investigated in the dilute limit by using the perturbation method. The local potentials in inclusion and host regions are derived at all harmonics. Moreover, the formulae of the effective linear and nonlinear responses are given in the dilute limit. 相似文献
12.
The perturbation method is used to study the effective nonlinear response of graded cylindrical composites with power-law gradient inclusions under a sinusoidal alternating current (AC) external field of finite frequency ω. In dilute limit, the local potentials and the formulae of effective nonlinear AC responses are derived at the fundamental frequency and the third harmonics. Furthermore, the general effective nonlinear responses are given and compared with the effective nonlinear AC responses of fundamental frequency and the third harmonics, and the relationships between the nonlinear effective AC response and the general effective nonlinear response are also determined. 相似文献
13.
WEIEn-Bo GUGuo-Qing 《理论物理通讯》2001,35(4):501-504
A perturbative approach is used to study the AC response of nonlinear compostie media,which obey a current-field relation of the form J=σE χ|E|^2E with comp[onents having nonlinear response at finite frequencies.For a sinusoidal applied field,we extend the local potential in terms of sinusoidal components at fundamental frequency and high-order harmonic frequencies to treat the nonlinear comosites.For nonlinear composite media with a low concentrations of spherical inclusions,we give the formulae of the nonlinear effective AC susceptibility χ3ω at the third harmonic frequency. 相似文献
14.
Russian Text Ignored Russian Text Ignored 《等离子体物理论文集》1977,17(6):353-361
The parametric excitation of longitudinal waves in an infinite homogeneous plasma by a pump field E (t) = E 0(t) sin (ω0t + φ(t)) is studied on the basis of the Vlasov equation, where the amplitude E 0(t) and the phase φ(t) are slowly varying compared with ω0 periodic functions. Firstly it is assumed that ω0 is much larger than the electron plasma frequency ωLe. In the second part the parametric instabilities are considered under the resonance condition ω0 ≈ ωLe. In both parts the threshold fields for the excitation of the longitudinal waves and their growth rates are calculated. As an example these values are analysed for both a sequence of pump impulses and a phase-moduated pump field. They are compared with the results received for a monochromatic pump field. 相似文献
15.
《Physics letters. A》1988,132(4):175-178
The nonlinear driven/damped differential equation ∂φ/∂t+a∂3φ/∂t∂2y+b∂3φ/∂3y+c∂φ/∂y+fφ∂φ/∂y= −ϵ sin (Ky-ωt)−γφ with a=0 (KdV equation) or b=0 (drift equation) is numerically studied in a parameter region where the energy tends to a constant, Es, for t→∞. It is found that Es(ϵ) traces a hysteresis curve when the driving amplitude ϵ is cyclically varied. 相似文献
16.
Liqiang Feng 《Molecular physics》2017,115(13):1562-1571
Chirp control on the molecular harmonic emission and distribution in H2+ has been theoretically investigated. The results show that (i) with the introduction of the up-chirped pulse, the intensities of the higher harmonics are decreased; while with the introduction of the down-chirped pulse, the intensities of the higher harmonics can be enhanced. When E(t) < 0.0, the harmonic emission events (HEEs) from the positive-H are higher than those from the negative-H; while when E(t) > 0.0, the HEEs from the negative-H are higher than those from the positive-H. As a result, when the higher harmonics are produced from E(t) < 0.0 or E(t) > 0.0, the positive-H or the negative-H plays the main role in the harmonic spectra. (ii) The distribution of the higher harmonics from the two-H nuclei can be controlled with the introduction of the chirps and the carrier-envelope-phases of the laser field. (iii) Some minima on the harmonic spectra can be obtained, which is attributed to the coupling of the two-center interference and the electron-nuclear dynamics. (iv) By properly superposing the harmonics from the down-chirped pulse, an isolated attosecond pulse (IAP) with the duration of 45 as can be obtained, which is nearly 1 order of magnitude enhancement in pulse intensity compared with the chirp- free case. 相似文献
17.
We present an experimental investigation of a
filamentation-assisted fourth-order nonlinear optical process in KTP
crystals pumped by intense 1.53~eV (807~nm) femtosecond laser
pulses. Femtosecond light pulses at 2.58~eV (480~nm) are generated
by the fourth-order nonlinear polarization (P4(ω 2 ) =
χ 4(ω 2 ,ω ,ω ,ω ,- ω 1
)E3(ω )E* (ω 1 ), where E(ω ) corresponds to
the pump frequency and E(ω 1 ) to the supercontinuum
generated through filamentation). If the system is seeded by a laser
beam at ω 1 or ω 2 and there are spatial and
temporal overlaps with the pump beam, E(ω 1 ) and E(ω
2 ) are simultaneously amplified. When the intensity of the seed
laser beam exceeds a certain intensity threshold, the contribution
of P4(ω ) = χ 4(ω ,ω 1 ,ω 2 ,-ω, - ω )E(ω 1 )E(ω 2 )(E* (ω))2 becomes non-negligible, and the amplification weakens. The
conversion efficiency from the pump to the signal at 2.58~eV
(480~nm) attains to 0.1%. 相似文献
18.
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
19.
利用不同加热机制产生的超热电子所导致的相干渡越辐射(CTR)在谐波分量强度比上的不同,给出了区分飞秒激光等离子体相互作用产生超热电子过程中的主要与次要加热机制的一种可能方法.得到了加热周期不同的加热机制所产生超热电子的比例与CTR谐波分量的二倍频和一倍频的强度比之间的具体关系式.如果在实验上测到此谐波分量强度比,就可以推出不同加热机制在加热过程中所起作用的大致比例关系.另外,CTR谐波分量的强度比还与超热电子的温度、实验上所使用靶的厚度有一定依赖关系,对此作了较为详细的讨论.
关键词:
相干渡越辐射
超热电子
加热机制 相似文献
20.
基于非线性耦合波理论分析了三倍频过程中群速度之间的关系,推导出三波混频条件下的群速匹配关系式.对超短脉冲在Ⅱ类KDP晶体中的混频过程进行了模拟分析,结果表明:当三波(基波ω,谐波2ω和3ω)的群速度满足该匹配关系式时,三倍频(3ω)的带宽和转换效率均可达最大值;而随着三波群速度对该关系式的偏离逐渐增大,带宽变窄、转换效率下降.导出的三波群速匹配关系式对寻找合适的色散晶体和选择有效的匹配措施、实现宽带三次谐波转换具有指导意义. 相似文献