电磁波在弱电离尘埃等离子体中非线性传输特性的理论研究

The research on electromagnetic properties of dusty plasmas has attracted much attention by scientists due to its profound theoretical and application value. In this project, we attempt to study the nonlinear propagation characters of electromagnetic waves and second harmonic generation in weakly ionized dusty plasmas. Consider the effect of wave-dusty plasmas nonlinear interaction on dust particles charging and discharging model and multi-collision process, and modify the effective dielectric function of weakly ionized dusty plasmas by orbit motion limited theory. Theoretically derive the propagation equations of single Gaussian wave, quadruple Gaussian wave, four incoherent (coaxial or non-coaxial) Gaussian waves in weakly ionized dusty plasmas. By analyzing the self focusing and mutual focusing phenomena, the spatial inhomogeneous distribution of floating potential of dust particles, the relationship of nonlinear propagation characters of electromagnetic waves and dusty plasmas parameters would be built, in order to realize the spatial distribution modulation of dust charges. Explore the physical process of electron plasma wave excitation and second harmonic generation, analyze the phase match condition and the effective dielectric function of second harmonic frequency, and then discuss the impact of dust particles on the generation efficiency and propagation characters of second harmonic wave.

尘埃等离子体电磁特性因其深远的理论及应用价值受到科学工作者的关注。本项目针对弱电离尘埃等离子体中电磁波非线性传输特性和二次谐波激发进行理论研究。考虑电磁波-尘埃等离子体非线性效应对尘埃颗粒充放电模型和多体碰撞过程的影响，结合轨道运动受限理论对弱电离尘埃等离子体有效介电函数进行修正。理论推导单束高斯光束、四重高斯光束、四束非相干（共轴或非共轴）高斯光束在弱电离尘埃等离子体中的传输方程。通过分析自聚焦和互聚焦、尘埃颗粒浮动电势空间非均匀分布等现象，建立电磁波非线性传输特性与弱电离尘埃等离子体特征参数的关系，而从实现尘埃颗粒带电量空间分布调制。理论研究电磁波在弱电离尘埃等离子体中激发电子等离子体波及耦合产生二次谐波的物理过程，分析相位匹配条件及二次谐波频率下弱电离尘埃等离子体有效介电函数，着重讨论尘埃颗粒对二次谐波激发效率及传输特征的影响。

电磁波与等离子体相互作用一直是科学工作者关注的重点，其前沿技术能够深入到空间通信、微波等离子体诊断、激光驱使核聚变等众多应用领域。利用电磁波在等离子体中传输，不仅能够反映等离子体内部物理信息，实现等离子体诊断，还可以通过激发非线性效应对电磁波频率、光斑形状等进行调制，因此具有重要的理论和应用价值。相较于电磁波在理想等离子体中非线性传输，尘埃颗粒的存在使非线性相互作用变得更加复杂。.本项目针对弱电离尘埃等离子体中电磁波非线性传输特性和尘埃颗粒充放电过程进行理论研究。考虑电磁波与尘埃等离子体非线性相互作用、尘埃颗粒充放电模型和多体碰撞过程的影响，结合轨道运动受限理论对弱电离尘埃等离子体有效介电函数进行修正。理论推导高斯光束、复杂光束在弱电离尘埃等离子体中的传输方程。通过分析自聚焦和互聚焦、尘埃颗粒浮动电势空间非均匀分布等现象，建立电磁波非线性传输特性与弱电离尘埃等离子体特征参数的关系，而从实现尘埃颗粒带电量空间分布调制。针对运动的尘埃颗粒在等离子体中的充电过程进行了理论分析和模拟仿真，对尘埃颗粒材质、尘埃颗粒定向运动速度及等离子体环境对充电过程的影响进行了细致的讨论，着重分析尘埃颗粒表面附着的电子及离子数目和表面浮动电势分布。该项目成果不仅对理解电磁波与尘埃等离子体非线性相互作用提供理论基础，还对设计特殊等离子体介电结构，实现尘埃颗粒调控提供新的方法。