We studied and demonstrated the emission of THz waves by the beating of two CW-laser beams in an axially modulated plasma in the presence of a static magnetic field (applied transversely to the direction of propagation of lasers) from two-dimensional particle-in-cell simulation. The ponderomotive-force-induced nonlinear current drives THz radiation with frequency close to the beat frequency (Δω = ω₁ − ω₂) that propagates in the forward direction. Inside the plasma, THz radiation consists of a mixture of linear and radial polarization, while outside the plasma, only linear polarization dominates; however, radial polarization is stronger in the case of unmagnetized plasma. When the ripple is used, several modes are excited and the mode excited at Δk = (k₁ − k₂) − k_q that meets the phase matching condition is resonantly enhanced. The THz field amplitude grows resonantly with time and it becomes saturated due to the excited higher-order mode coupling. The saturation level is reached about five times higher than the nonrippled plasma case in the vacuum side.

中文翻译：

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轴向调制磁化等离子体的相位匹配太赫兹发射的仿真研究

我们研究并证明了在二维磁场中存在静磁场（垂直于激光传播方向）的情况下，在轴向调制的等离子体中，两个CW激光束的搏动产生了THz波的发射。细胞模拟。有质动力诱导的非线性电流驱动器THz辐射与频率接近拍频（Δω=ω ₁ - ω ₂），其在向前的方向上传播。在等离子体内部，太赫兹辐射由线性和径向极化的混合物组成，而在等离子体外部，仅线性极化占主导。然而，在未磁化等离子体的情况下，径向极化更强。使用纹波时，会激发几种模式，并且在Δk=（k ₁ − k₂）-满足相位匹配条件的k _q共振增强。THz场振幅随时间共振增长，并且由于激发的高阶模式耦合而变得饱和。在真空侧达到的饱和度比不波纹等离子体的情形高约五倍。