Tunable X-ray sources from a laser-driven wakefield have wide applications. However, due to the difficulty of electron dynamics control, currently the tunability of laser wakefield–based X-ray sources is still difficult. By using three-dimensional particle-in-cell simulations, we propose a scheme to realize controllable electron dynamics and X-ray radiation. In the scheme, a long wavelength drive pulse excites a plasma wake and an off-axis laser pulse with a short wavelength co-propagates with the drive pulse and ionizes the K-shell electrons of the background high-Z gas. The electrons can be injected in the wakefield with controllable transverse positions and residual momenta. These injected electrons experience controllable oscillations in the wake, leading to tunable radiations both in intensity and polarization.

中文翻译：

---

通过在激光尾波加速中使用离轴电离注入来控制Betatron辐射偏振

来自激光驱动的尾场的可调X射线源具有广泛的应用。但是，由于电子动力学控制的困难，目前基于激光尾波的X射线源的可调性仍然很困难。通过使用三维粒子模拟，我们提出了一种实现可控电子动力学和X射线辐射的方案。在该方案中，长波长驱动脉冲激发等离子体唤醒，短波长离轴激光脉冲与驱动脉冲共同传播，并使背景高Z气体的K壳电子电离。电子可以以可控制的横向位置和剩余动量注入尾流场。这些注入的电子在尾流中经历可控的振荡，从而导致强度和极化强度的可调辐射。