Reviews Of Accelerator Science And Technology - Volume 9: Technology And Applications Of Advanced Accelerator Concepts

Volume 9: Technology and Applications of Advanced Accelerator Concepts

Alexander W Chao, Weiren Chou;;;

• Publisher: WSPC
• Year: 2017
• eBook ISBN: 9789813209596
• Topic: Physical Sciences
• Subtopic: Electromagnetism

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Since its invention in the 1920s, particle accelerators have made tremendous progress in accelerator science, technology and applications. However, the fundamental acceleration principle, namely, to apply an external radiofrequency (RF) electric field to accelerate charged particles, remains unchanged. As this method (either room temperature RF or superconducting RF) is approaching its intrinsic limitation in acceleration gradient (measured in MeV/m), it becomes apparent that new methods with much higher acceleration gradient (measured in GeV/m) must be found for future very high energy accelerators as well as future compact (table-top or room-size) accelerators. This volume introduces a number of advanced accelerator concepts (AAC) — their principles, technologies and potential applications. For the time being, none of them stands out as a definitive direction in which to go. But these novel ideas are in hot pursuit and look promising. Furthermore, some AAC requires a high power laser system. This has the implication of bringing two different communities — accelerator and laser — to join forces and work together. It will have profound impact on the future of our field.

Also included are two special articles, one on "Particle Accelerators in China' which gives a comprehensive overview of the rapidly growing accelerator community in China. The other features the person-of-the-issue who was well-known nuclear physicist Jerome Lewis Duggan, a pioneer and founder of a huge community of industrial and medical accelerators in the US.

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Laser-Driven Plasma Electron Acceleration and Radiation

Kazuhisa Nakajima

Center for Relativistic Laser Science,
Institute for Basic Science (IBS), Gwangju 61005, South Korea
[email protected]

Laser-driven plasma acceleration of electron beams is reviewed from the viewpoint of the underlying physics and recent progress in the experimental research. Betatron radiation cogenerated from laser plasma accelerators is mentioned in terms of electron beam dynamics and the radiation spectrum. At the end, future perspectives of possible applications are presented.

Keywords: Laser plasma accelerators; laser wakefield acceleration; betatron radiation; laser-driven FEL; high-energy frontier collider.

1. Introduction

Laser-driven plasma accelerators are one of the prevailing advanced accelerator concepts that provide us with compact particle and radiation sources for a wide range of sciences. In contrast to structurebased accelerators, including conventional radio frequency (RF) accelerators and advanced accelerator concepts, plasma-based accelerators sustain an ultrahigh-gradient accelerating field of the order of 100GV/m in plasma at an electron density of ∼10¹⁸ cm⁻³, free from the material breakdown and surface heating that limits the maximum accelerating field of structure-based accelerators. Since such ultrahigh fields are generated in a form of largeamplitude plasma wake as a result of electron and ion charge separation produced by an ultrafast laser pulse propagating in plasma nearly at the speed of light, energetic electrons are dominantly trapped and accelerated, while ions remain at rest during the interaction with wakefields. In that scenario, this article concentrates on electron acceleration and radiation based on laser wakefield accelerators. From the viewpoints of particle acceleration physics and a broad range of potential applications, laser-driven ion plasma accelerators are currently also vibrant topics for advanced accelerator research, as referenced in Ref. 1.

Historically, laser-driven plasma acceleration has evolved from a groundbreaking concept by Tajima and Dawson [2] into a potential technology for the next-generation particle accelerators, which was motivated by a long-standing consciousness that the state-of-the-art high-energy accelerators had become too large and costly, and possibly had approached the end of the road [3]. To date, high-energy accelerators are based on high-power RF technologies that accelerate charged particles with electric fields up to 100MV/m at most, which is a limit stably produced in metallic, electromagnetic cavities due to electrical surface heating and breakdown. As illustrated with the Large Hadron Collider (LHC) [4] and the future linear collider [5] beyond the TeV energy range, the overall accelerator complex will range over several tens of kilometers in size and require enormous expenditure to be built. A remarkable scaling-down of high-energy accelerators may be simply brought about by using much higher accelerating fields than the present limits. In this context, various novel concepts of charged particle accelerators that utilize superhigh fields of lasers and plasmas have been proposed at the early time of the laser, since the 1960s [6].

In the meantime, experimental progress in laser wakefield acceleration of electron beams was initiated by demonstrating ultrahigh-gradient acceleration of the order of ∼100GeV/m, using chirped pulse amplification lasers with 10TW class peak power and 1 ps pulse duration, focused onto a gas jet [7, 8]. Such experiments were characterized in terms of the selfmodulated wakefield regime [9], where laser power should be higher than the critical power for relativistic self-focusing and a laser pulse duration is longer than a plasma period. In this regime, the laser pulse undergoes temporal intensity modulation and self-guiding through nonlinear interactions with plasma so that large-amplitude plasma waves can be resonantly excited. Ultimately, their wave breaking occurs, generating relativistic electrons to be continuously trapped and accelerated by wakefields throughout an acceleration distance. Therefore, electron beams produced fro...

Table of contents

• Cover page
• Title page
• Copyright
• Editorial Preface
• Contents
• Roadmap to the Future
• Laser-Driven Plasma Electron Acceleration and Radiation
• Electron and Positron Beam–Driven Plasma Acceleration
• Proton-Beam-Driven Plasma Acceleration
• Dielectric Laser Accelerators: Designs, Experiments, and Applications
• Dielectric Wakefield Accelerators
• Laser Technology for Advanced Acceleration: Accelerating Beyond TeV
• Simulations for Plasma and Laser Acceleration
• Luminosity Limitations of Linear Colliders Based on Plasma Acceleration
• Application of Advanced Accelerator Concepts for Colliders
• Advanced Accelerators for Medical Applications
• Book Review — Engines of Discovery: A Century of Particle Accelerators (Revised Ed.)
• Particle Accelerators in China
• Jerome Lewis Duggan: A Nuclear Physicist and a Well-Known, Six-Decade Accelerator Application Conference (CAARI) Organizer