论文标题
在光电离等离子体和等离子通道中伴随激光唤醒的单周期THZ信号
Single-cycle THz signal accompanying laser wake in photoionized plasmas and plasma channels
论文作者
论文摘要
飞秒，Terawatt Laser脉冲的光电离子在中性环境气体中产生血浆柱。电子的速度是由沿圆柱表面的激光浮子力推动的，将圆柱边界处的径向密度梯度耦合，产生方位角极化的THZ旋转电流（RC）。相同的机制在泄漏的等离子体通道中产生低频RC。在通道上施加外部电压可诱导径向不均匀的电子流（直流电流）和常数方位角极化磁场。将它们耦合到电子密度扰动中，还会向RC增加两个术语。等离子体柱中的表面RC支持伴随唤醒的宽带，evanscent的Thz信号。距离圆柱几毫米，高频组件的快速消失将此THZ信号变成了径向极化的单周期脉冲。
Photoionization by a femtosecond, terawatt laser pulse generates a plasma column in a neutral ambient gas. Velocity of electrons, pushed by the laser ponderomotive force along the column surface, couples to the the radial density gradient at the column boundary, generating an azimuthally polarized THz rotational current (RC). The same mechanism produces the low-frequency RC in a leaky plasma channel. Applying external voltage to the channel induces a radially non-uniform electron flow (direct current) and a constant, azimuthally polarized magnetic field. Coupling them to the electron density perturbations adds two more terms to the RC. The surface RC in the plasma column supports a broadband, evanescent THz signal accompanying the wake. A few millimeters away from the column, rapid evanescence of high-frequency components turns this THz signal into a radially polarized, single-cycle pulse.
