Two Dimensional Dynamics Of The Plasma Wakefield Accelerator

The plasma wakefield accelerator (PWFA) is an accelerator concept based on utilizing a large amplitude plasma wave to accelerate relativistic electrons to ultra-high energy. The plasma wave represents the wave produced by a relativistic beam as it passes through a cold plasma. As the beam enters the plasma its space charge polarizes the background. When the beam tail passes the plasma is left with a large oscillating induced charge. The wakefields are derived assuming that the charge and current profiles of the driving bunch remain fixed. An estimate is made of the condition necessary for maintaining the profile of the driving bunch. The current required to result in an accelerating field approaching the wavebreaking limit is estimated. The beam dynamics for a small beam are simulated based on these estimates. The results of the studies reported indicate that the self-consistent transverse motion of the driving bunch makes pulse tailoring impossible to maintain. 4 refs., 5 figs. (LEW).

This thesis focuses on a cutting-edge area of research, which is aligned with CERN's mainstream research, the "AWAKE" project, dedicated to proving the capability of accelerating particles to the energy frontier by the high energy proton beam. The author participated in this project and has advanced the plasma wakefield theory and modelling significantly, especially concerning future plasma acceleration based collider design. The thesis addresses electron beam acceleration to high energy whilst preserving its high quality driven by a single short proton bunch in hollow plasma. It also demonstrates stable deceleration of multiple proton bunches in a nonlinear regime with strong resonant wakefield excitation in hollow plasma, and generation of high energy and high quality electron or positron bunches. Further work includes the assessment of transverse instabilities induced by misaligned beams in hollow plasma and enhancement of the wakefield amplitude driven by a self-modulated long proton bunch with a tapered plasma. This work has major potential to impact the next generation of linear colliders and also in the long-term may help develop compact accelerators for use in industrial and medical facilities.

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.

Since the mid-twentieth century, accelerators and colliders have been at the forefront of science and technology in the fields of space, medicine, energy, and others. This book presents sophisticated knowledge about accelerators and colliders and their crucial technological applications. With six chapters, the book presents information about currently available accelerators and colliders as well as novel schemes for future systems. Other topics covered include vacuum systems, elementary particles, and quantum chromodynamics.