School of Natural Science, UNIST, 50 UNIST-gil, Ulju-gun, Ulsan, 44919, Korea.
Department of Physics, Scottish Universities Physics Alliance and University of Strathclyde, Glasgow, G4 0NG, UK.
Sci Rep. 2018 Jan 9;8(1):145. doi: 10.1038/s41598-017-18399-3.
Emission of radiation from electrons undergoing plasma oscillations (POs) at the plasma frequency has attracted interest because of the existence of intriguing and non-trivial coupling mechanism between the electrostatic PO and the emitted electromagnetic wave. While broadband emission from plasma waves in inhomogeneous plasma is well known, the underlying physics of narrowband emission at the plasma frequency observed in experiments and in solar radio-bursts is obscure. Here we show that a spatially-localized plasma dipole oscillation (PDO) can be generated when electrons are trapped in a moving train of potential wells produced by the ponderomotive force of two slightly detuned laser pulses that collide in plasma and give rise to a burst of quasi-monochromatic radiation. The energy radiated in the terahertz spectral region can reach an unprecedented several millijoules, which makes it suitable for applications requiring short pulses of high-intensity, narrowband terahertz radiation.
电子在等离子体频率下发生等离子体振荡（POs）时发出的辐射引起了人们的兴趣，因为静电 PO 与发射的电磁波之间存在有趣且非平凡的耦合机制。虽然在非均匀等离子体中已经观察到等离子体波的宽带发射，但实验和太阳射电爆发中观察到的等离子体频率处窄带发射的基本物理仍不清楚。在这里，我们表明，当电子被囚禁在由两个略微失谐的激光脉冲的压力产生的势阱的移动列车中时，可以产生空间局部化的等离子体偶极子振荡（PDO），这两个激光脉冲在等离子体中碰撞并产生突发的准单色辐射。在太赫兹光谱区域辐射的能量可达到前所未有的几毫焦耳，这使其适用于需要高强度、窄带太赫兹辐射的短脉冲应用。
