Terahertz laser modulation of electron beams
Terahertz laser modulation of electron beams
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DOI：
10.1063/1.3075563
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发表时间：
2009-03-01
影响因子：
3.2
通讯作者：
Wu, Z.
中科院分区：
文献类型：
--
作者：
Neumann, J. G.;Fiorito, R. B.;Wu, Z.
调制电子束的研究是重要的，因为它们可以用来产生相干辐射，但调制可能会导致不必要的不稳定性，在某些设备。具体地，在自由电子激光器中，在期望的发射频率下的适当的预聚束可以增强性能，而由不稳定性和聚束压缩方案引起的聚束可以降低性能。在光注入器加速器中，定制驱动激光脉冲的形状可以用作增强或减轻这些调制的效果的技术。这项工作探讨了在光阴极产生深度调制的电子束的可能性，通过使用修改后的驱动激光器设计产生多个亚皮秒脉冲重复太赫兹频率。纵向空间电荷力可以通过将密度调制转换为能量调制来强烈影响调制的演化。在布鲁克海文国家实验室的源开发实验室的电子加速器和PARMELA模拟的实验被用来探索具有不同的电荷和不同的初始调制的电子束的动力学。最后，利用过渡辐射器产生的太赫兹光来确定电子束的结构。
The study of modulated electron beams is important because they can be used to produce coherent radiation, but the modulations can cause unwanted instabilities in some devices. Specifically, in a free electron laser, proper prebunching at the desired emission frequency can enhance performance, while bunching resulting from instabilities and bunch compression schemes can degrade performance. In a photoinjector accelerator, tailoring the shape of the drive laser pulse could be used as a technique to either enhance or mitigate the effect of these modulations. This work explores the possibility of creating deeply modulated electron beams at the photocathode by using a modified drive laser designed to produce multiple subpicosecond pulses repeated at terahertz frequencies. Longitudinal space charge forces can strongly influence the evolution of modulations by converting density modulations to energy modulations. Experiments at the Source Development Laboratory electron accelerator at Brookhaven National Laboratory and PARMELA simulations are employed to explore the dynamics of electron beams with varying charge and with varying initial modulation. Finally, terahertz light generated by a transition radiator is used to confirm the structure of the electron beam.