Control of electron injection in laser wakefield acceleration for high quality electron beams

高质量电子束激光尾场加速中电子注入的控制

• 批准号: 2158720
• 金额: --
• 依托单位: University of Strathclyde
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2158720
• 关键词: Control; electron; injection; laser; wakefield

The laser wakefield acceleration (LWFA) driven in plasma is highly attractive for its extremely high acceleration gradients and the potential to produce ultrashort electron bunches and X-ray radiation down to attosecond duration. Presently, the extremely high acceleration gradients have been well-demonstrated, for example, by producing multi-GeV electron beams in an accelerating distance of less than 10cm. However, the beam quality including the beam energy spread and emittance still needs to be improved and the potential to ultrashort electron bunches and X-ray radiation down to attosecond duration needs to be further explored. To produce electron beams with high quality and high stability, the control of electron injection into the acceleration buckets is critical. This remains a great challenge in LWFA. Many schemes of electron injection have been proposed and some of them have also been tested experimentally, such as ionisation injection, injection by use of plasma density gradients, and colliding laser injection etc. The key to reduce the beam energy spread is to confine the electron injection to a short distance length as suggested by previous investigations in this area. In this PhD project, the student will study new schemes based upon the combination of different injection schemes by tailoring both the laser and plasma distributions. For example, the combination of the ionisation injection and density upramp injection may considerably reduce the injection length. The use of circularly-polarised laser and a longitudinal DC magnetic field/plasma channel helps to tune the laser group velocity, which may eventually tune the acceleration process. The proposed new schemes should be robust and relatively easy to implement experimentally. The aim is to achieve electron beam energy spread less than 1% with charge over 30pC and/or bunch duration less than 1fs. The new schemes will be based upon theoretical analysis and demonstrated by 3D PIC simulations.

等离子体驱动的激光尾流场加速（LWFA）因其极高的加速梯度和产生超短电子束和持续时间低至阿秒的x射线辐射的潜力而具有很高的吸引力。目前，极高的加速梯度已经得到了很好的证明，例如，在小于10cm的加速距离内产生多gev的电子束。但是，光束质量（包括光束能量扩散和发射度）仍有待提高，超短电子束和低至阿秒持续时间的x射线辐射的潜力有待进一步探索。为了产生高质量、高稳定性的电子束，加速桶内电子注入的控制至关重要。这仍然是LWFA面临的一个巨大挑战。人们提出了许多电子注入方案，并对其中一些方案进行了实验验证，如电离注入、等离子体密度梯度注入和碰撞激光注入等。减少束流能量扩散的关键是将电子注入限制在较短的距离内，这是该领域以往研究的建议。在这个博士项目中，学生将通过调整激光和等离子体分布来研究基于不同注射方案组合的新方案。例如，电离注入和密度提升注入的组合可以大大缩短注入长度。圆极化激光和纵向直流磁场/等离子体通道的使用有助于调整激光群速度，这可能最终调整加速过程。所提出的新方案应具有鲁棒性，并且相对容易在实验中实现。目标是实现电子束能量扩散小于1%，电荷超过30pC，束束持续时间小于1fs。新方案将以理论分析为基础，并通过三维PIC模拟进行验证。