Development of a multi-pulse laser wakefield electron accelerator operating at kHz rep-rate

开发以 kHz 重复频率运行的多脉冲激光尾场电子加速器

基本信息

批准号：
1947809
负责人：
金额：
--
依托单位：
University of Oxford
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1947809
关键词：
Development multi pulse laser wakefield

项目摘要

Summary: Laser-driven plasma accelerators can already accelerate electrons to GeV-scale energies in accelerator stages only a few centimetres long. However, the driving lasers used to date can only operate at best at a few pulses per second, and have very low wall-plug efficiencies.The laser-plasma accelerator group at Oxford has pioneered a novel approach for overcoming these limitations: the multi-pulse laser wakefield accelerator (MP-LWFA). In this approach the plasma wakefield is driven by a train of low energy laser pulses. If these pulses are spaced by the plasma period then the wakefields driven by the pulses add coherently, yielding a plasma wave which grows towards the back of the pulse train.The Oxford team recently demonstrated this approach for the first time in experiments performed at the Rutherford Appleton Laboratory (RAL). In that work it was shown that plasma wakefields could indeed be resonantly excited by a train of laser pulses, confirming this validity of this approach.However, to date electrons have not been accelerated by this method since the wakefields driven by MP-LWFA are linear, and as such do not self-trap electrons from the background plasma. The aim of this project is to develop techniques for controlling the injection of electrons into the quasi-linear wakefields driven by a MP-LWFA.Two approaches will be studied. In the first, the use of additional laser pulses to ionize a dopant species will be explored. If a short laser pulse (the "injection" pulse) is focused in the wake driven by the pulse train, then electrons ionized by the second laser pulse can be trapped into the wakefield, and then accelerated. The second approach to be explored will be down-ramp injection. In this method the density of the plasma decreases rapidly with longitudinal position; this slows the wakefield as it moves down the ramp, making it easier for electrons to be trapped, and then accelerated.These injection techniques will be studied through numerical simulations with particle-in-cell (PIC) codes, and compared to the results of experiments performed in Oxford, RAL, and other laser facilities.If successful this work will open the route to a new generation of very compact plasma accelerators operating at multi-kilohertz pulse repetition rates. These would immediately find applications in driving very compact X-ray sources, with widespread utility in ultrafast science, technology, and medicine.

摘要：激光驱动的等离子体加速器已经可以将电子加速到GEV尺度的加速器阶段的GEV尺度能量。但是，迄今为止，驾驶激光器只能以每秒几个脉冲的速度最多运行，并且具有非常低的壁插头效率。牛津大学的激光 - 铂加速器组开创了一种克服这些限制的新方法：多脉冲激光器Wakefield Accelfield Accelator（MP-LWFA）。在这种方法中，等离子体韦克菲尔德是由低能激光脉冲驱动的。如果这些脉冲被等离子体周期间隔，则脉冲驱动的尾场会相干地增加，从而产生了朝向脉冲序列的后部生长的等离子体波。牛津队最近在Rutherford Appleton Laboratory（Ral）进行了实验中首次在实验中首次演示了这种方法。在这项工作中，证明了血浆韦克菲尔德确实可以通过激光脉冲的火车来共振，从而证实了这种方法的这种有效性。但是，迄今为止，这种方法还没有加速电子，因为MP-LWFA驱动的Wakefields是线性的，并且因此没有来自背景等离子的自我Trap电子。该项目的目的是开发用于控制电子将电子注入到由MP-LWFA驱动的准线性韦克菲尔德的技术。首先，将探索使用其他激光脉冲将掺杂剂物种离子化。如果将短的激光脉冲（“注射”脉冲）聚焦在由脉冲序列驱动的尾流中，则可以将第二激光脉冲电离的电子被捕获到韦克菲尔德，然后加速。要探索的第二种方法是向下注射。在这种方法中，血浆的密度随纵向位置迅速降低。这会减慢韦克菲尔德的向下移动，使电子更容易被捕获，然后加速。这些注射技术将通过具有粒子内（PIC）代码的数值模拟进行研究，并与在牛津，Ral和其他激光器设备上进行的实验结果相比，将其开放的途径非常紧缩。多吉洛兹脉冲重复率。这些将立即在推动非常紧凑的X射线源方面找到应用，并在超快科学，技术和医学方面广泛实用。