项目名称: 激光尾波场加速中横向光离化注入对电子的控制
项目编号: No.11205101
项目类型: 青年科学基金项目
立项/批准年度: 2013
项目学科: 物理学II
项目作者: 陈民
作者单位: 上海交通大学
项目金额: 28万元
中文摘要: 激光尾波场加速中的电子注入控制已成为制约电子束质量的一个关键问题。初始注入电量、能散和横向动量分布直接关系到最终束团能谱和横向发射度。而这些又是将来电子束在后续应用中的关键性指标。我们拟利用三光束方案进行尾波场中的电子离化注入控制,以期得到比现有注入方式小一个量级的横向发射度;主动控制电子束团在尾波场中的横向位置,为将来的基于激光尾波场的辐射源做准备。方案中驱动激光部分电离具有高Z的气体,并形成尾波场;两超短脉冲在后续尾波场中进行横向碰撞,形成拍频场离化尾波中离子的内壳层电子,并使之被尾波捕获,进而得到加速。由于拍频场的电场方向与驱动激光的传输方向相同,所以由于离化而产生的残余动量不再在尾波场的横向,可以大大减小注入电子的横向发射度;通过调节拍频场的位置和长度可以对电子束的横向注入位置和大小进行控制。研究对电子束的应用(如X射线辐射源、自由电子激光、正负电子对撞机注入源等)具有重要意义。
中文关键词: 尾波加速;激光加速;电子注入;离化注入;发射度
英文摘要: Electron injection has been a bottle-net to increase the final accelerated beam's quality. Initial injection number, transversal and longtitudinal momentum spreads are critically important to the final accelerated beam's energy spectrum and transverse emittance, which are also the critial index for their potential applications. We propose to use a three-pulse scheme to perform ionization injection in a laser plasma wakefield accelerator to reduce the transverse emittance of the beam by one order compared wtih current injection methods, and we want to actively control the transverse injection position for the future studies of X-ray source based on laser plasmaaccelerator. In our scheme, the driver pulse will partly ionize the high Z neutral gas medium and excite a wakefield. Two transvese propagating ultra short laser pulses collide in the following wakefield and form a beat wave. The electric field of the beat wave ionizes the high-order electrons of the ions inside the wake, and some of these electrons will be trapped and accelereted by the wakefield. Since the direction of the electric field inside the beat wave is along the longitudinal direction of the wake, the residual ioniation momentum will no longer in the transverse direction, which could reduce the beams's final transverse emittance by one order. Thr
英文关键词: wakefield acceleration;laser acceleration;electron injection;ionization injection;emittance