Covariant analysis of accelerating charged beams and plasmas

这项工作的目的是为未来高能和低能粒子加速器的发展做出贡献。高能粒子物理学在帮助解释我们周围世界的基本结构方面取得了相当大的成功。然而，该领域的持续发展依赖于新型粒子加速器的发展，这本身就带来了相当大的物理和工程挑战。随着粒子加速器变得越来越强大，它们也变得越来越庞大和昂贵。如果更高能量的实验要保持实用性，就需要创新的加速方案。这一点在30公里长的ILC（国际直线对撞机）和更激进的CLIC（紧凑型直线对撞机）上得到了清楚的说明，前者是根据传统的加速方案设计的，后者承诺在相同的加速器长度上实现三倍于前者的粒子能量。CLIC的工作原理是使用两个像变压器一样运行的粒子束。由长束电子组成的驱动束被加速并转换成短得多的电子束，然后这些电子束被减速以为主束加速器提供动力。在转换阶段，对束动力学的详细了解对这种新型机器的成功至关重要。低能量加速器是用于研究物质结构的强光源的组成部分之一。在传统的自由电子激光器中，利用射频微波腔内的电场加速集束电子，然后通过注入波动器强制发射相干光。这种光源的成本和尺寸，主要是由于加速器组件，禁止在大学院系中安置它们，它们只能作为昂贵的大型共享设施使用。然而，激光驱动等离子体尾流场加速是一种非常有前途的替代加速方案，近年来已经取得了许多实验成功。这种激进的方法利用等离子体中激光脉冲产生的巨大电场来加速激光脉冲后尾迹中的电子。它承诺提供高度紧凑的（桌面）飞秒持续时间的强电磁脉冲源，用于在前所未有的时间和空间尺度上探测物质。未来，大学院系可能会基于这一概念安装自己的光源。然而，许多重要的问题仍有待解决，因为加速的电子束还不能满足产生必要质量的电磁脉冲所需的所有严格标准。提出的工作中心是开发新的和强大的数学模型，以解决CLIC和激光驱动等离子体尾流场加速的基本问题。这两种加速方案都涉及相互作用带电粒子集合的详细动力学，所提议的工作旨在支持它们的持续发展。

The aim of the proposed work is to contribute to the development of future high-energy and future low-energy particle accelerators. Considerable success has been enjoyed by high-energy particle physics in helping to explain the fundamental structure of the world around us. However, on-going progress in this field relies on novel particle accelerator development, which itself poses considerable physics and engineering challenges. As particle accelerators become more powerful they also become prohibitively large and expensive. Innovative acceleration schemes are required if ever higher energy experiments are to remain practical. This is clearly illustrated by the 30km long ILC (International Linear Collider), designed on conventional acceleration schemes, and the more radical CLIC (Compact Linear Collider) which promises to achieve particle energies that are three times greater over the same accelerator length. CLIC works by employing two particle beams operating like a transformer. A drive beam composed of long bunches of electrons is accelerated and converted into bunches of much shorter length which are then decelerated to power the main beam accelerator. A sound knowledge of the detailed bunch dynamics during the conversion stage is critical for the success of this novel machine. Lower energy accelerators are one of the components of intense light sources used to study the structure of matter. In conventional free-electron lasers, bunched electrons are accelerated using the electric fields inside radio-frequency microwave cavities and then forced to emit coherent light by injection into an undulator. The cost and size of such light sources, mostly due to the accelerator component, prohibit housing them in university departments and they are only accessible as expensive large shared facilities. However, laser-driven plasma wakefield acceleration is a highly promising alternative acceleration scheme that has seen much experimental success in recent years. This radical approach exploits the huge electric fields created by a laser pulse in a plasma to accelerate electrons in the wake behind the laser pulse. It promises to deliver highly compact ( table-top ) sources of intense electromagnetic pulses of femtosecond duration for probing matter on unprecedented temporal and spatial scales. In the future, university departments could be housing their own light sources based on this concept. However, a number of important issues remain to be resolved because the accelerated electron bunches do not yet satisfy all the stringent criteria needed to produce electromagnetic pulses of the necessary quality. The proposed work centres on the development of new and powerful mathematical models to address fundamental issues in CLIC and laser-driven plasma wakefield acceleration. Both acceleration schemes involve detailed dynamics of collections of interacting charged particles and the proposed work seeks to support their on-going development.