High-density electron-bunch train–based tunable coherent terahertz radiation with a narrow spectral bandwidth is highly essential for many scientific applications. Here we propose a scheme to produce ultrahigh-peak-current (more than 10 kA) electron-bunch trains with tunable picosecond spacing for the generation of such terahertz sources. Passing through a plasma section and interacting with the self-excited nonlinear plasma wake, the beam gains a “sawtooth” energy modulation. By means of magnetic optics, it is then effectively converted into a beam density modulation forming microbunches with a high charge of up to a few nanocoulombs and a bunching factor as high as approximately $0.8$. Tunable narrowband terahertz radiation with energy on the order of 10 mJ can be generated, which we show in both theoretical analyses and simulations via this process. This scheme can be realized in accelerator facilities with repetition rates on the order of kilohertz or even submegahertz, which provides great potential in modern science and related technologies.

中文翻译：

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通过非线性等离子体韦克菲尔德调制产生可调谐的10mJ级太赫兹脉冲

对于许多科学应用而言，具有窄光谱带宽的基于高密度电子束火车的可调谐相干太赫兹辐射非常重要。在这里，我们提出了一种方案，用于产生具有可调皮秒间隔的超高峰值电流（大于10 kA）电子束流列车，用于产生此类太赫兹源。通过等离子体部分并与自激非线性等离子体唤醒相互作用，光束获得“锯齿状”能量调制。然后通过电磁光学将其有效地转换为束密度调制，从而形成微束，该束具有高达几个纳米库仑的高电荷，并且聚束因子高达大约$0.8$。可以产生能量约为10 mJ的可调谐窄带太赫兹辐射，我们通过该过程在理论分析和仿真中均显示了这一点。可以在加速器设备中实现这种方案，其重复频率约为千赫兹甚至几兆赫兹，这在现代科学和相关技术中具有巨大的潜力。