Phase Space Dynamics in Plasma Based Wakefield Acceleration

This book explores several key issues in beam phase space dynamics in plasma-based wakefield accelerators. It reveals the phase space dynamics of ionization-based injection methods by identifying two key phase mixing processes. Subsequently, the book proposes a two-color laser ionization injection scheme for generating high-quality beams, and assesses it using particle-in-cell (PIC) simulations. To eliminate emittance growth when the beam propagates between plasma accelerators and traditional accelerator components, a method using longitudinally tailored plasma structures as phase space matching components is proposed. Based on the aspects above, a preliminary design study on X-ray free-electron lasers driven by plasma accelerators is presented. Lastly, an important type of numerical noise-the numerical Cherenkov instabilities in particle-in-cell codes-is systematically studied.

Auteur
Xinlu Xu received his B.Sc. in engineering physics from Tsinghua University, China in 2008. He obtained his Ph.D. in nuclear science and technology from Department of Engineering Physics, Tsinghua University in Jan. 2015. His major research project in Prof. Wei Lu's group is phase space dynamics in plasma based wakefield acceleration. Subsequently, he became a post-doc fellow working with Prof. Warren B. Mori at Physics and Astronomy Department, University of California, Los Angeles, focusing on the generation, transportation of high quality electrons from plasma based wakefield accelerators and the development of high-fidelity particle-in-cell codes. Now he is working at SLAC National Accelerator Laboratory as a staff scientist to pursing high quality high energy acceleration in plasmas and study various interactions between intense beam, laser and plasmas.

Contenu

Chapter 1 Introduction

1.1 Introduction

1.2 Plasma Based Acceleration

1.3 Particle-in-Cell Simulations

1.4 Motivation and Outline

Chapter 2 Phase Space Dynamics of Injected Electron Beams in Ionization Injection

2.1 Introduction

2.2 The Photoionization Process

2.3 The Residual Momentum

2.3.1 Initial Momentum from the Tunneling Ionization

2.3.2 The Momentum from the Lasers: Longitudinal Injection

2.3.3 The Momentum from the Lasers: Transverse Injection

2.3.4 The Thermal Emittance

2.4 Single Particle Motion in the Nonlinear Wake

2.5 Transverse Phase Mixing

2.5.1 Emittance Evolution: Growth and Oscillation in the Injection Stage

2.5.2 Emittance Evolution: Decrease and Regrowth in the Acceleration Stage

2.5.3 A Phenomenological Model

2.5.4 Comparisons with PIC Simulations

2.6 Longitudinal Phase Mixing

2.6.1 The Trapping Condition

2.6.2 Longitudinal Phase Mixing

2.7 Space Charge Effects

2.8 The Two-Color Ionization Injection

2.8.1 The Emittance in A Single Laser Case

2.8.2 The Two-Color Ionization Injection: Longitudinal Injection

2.8.3 The Two-Color Ionization Injection: Transverse Injection

2.9 Intrinsic Phase Space Discretization in Laser Triggered Ionization Injection

2.9.1 Single Laser Pulse Case

2.9.2 Beam Driver with a Laser Injector

2.10 Summary