Coherent X-ray Generation by Laser Wakefield

我们一直在研究用等离子体加速粒子。在这些研究中，发现横向等离子体尾波场使光束垂直于其轴线移动。一种可以实现的几何结构，其中这种光束漂移变得周期性和连续，使得基于波荡器原理的同步辐射能够发射。本研究的最终目标是对这种辐射发射进行实验验证。实现这一目标的一步一步的里程碑是：1)理论研究，2)激光在气体中传输的研究，3)激光与飞秒范围内粒子束的同步，4)粒子束的激光尾迹加速，5)激光和粒子束的组合产生辐射(在没有等离子体的情况下)，建立飞秒范围的X射线探测技术，6)用等离子体波动产生X射线，步骤1)-5)的结果已经在今年完成。每一步都包含了世界上第一个实验结果；例如，在步骤2)中验证了激光的光导，在步骤4)中观察到了超过100 MeV的能量增益。这些都是在与日本宇宙航空研究开发机构和东京大学的NERL合作下制作的。

We have been studying particle acceleration using plasmas. In these studies, it was found that the transverse plasma wakefield shifts the beam normal to its axis. A geometry is realizable in which this beam shift becomes periodic and continuous, enabling emission of the synchrotron radiation based on the principle of the undulator.The final goal of the present study is the experimental demonstration of this radiation emission. Step-by-step milestones to reach the goal are :1) theoretical study,2) study of laser propagation in a gas,3) synchronization between laser beams and particle beams in femtosecond range,4) laser wakefield acceleratoin of particle beams,5) radiation generation by the combination of laser beams and particle beams (in the absence of plasmas), and establishment x-ray detection technique in the femtosecond range,6) x-ray generation by the plasma undulatorResults in steps 1)-5) have been accomplished in this year. Each of the step contains the first experimental result in the world ; For example, optical guiding of lasers were verified in step 2), and energy gain exceeding 100MeV was observed in step 4). These have been made under collaboratoin with JAERI and NERL,Univ.of Tokyo.