Control of Electron Injection and Acceleration in Laser-Wakefield Accelerators PDF Download
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Author: Emilien Guillaume
Publisher:
ISBN:
Category :
Languages : en
Pages : 228
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Book Description
Author: Emilien Guillaume
Publisher:
ISBN:
Category :
Languages : en
Pages : 228
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Book Description
Author: Matthew Philip Tooley
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The laser wakefield accelerator (LWFA) is a nascent electron acceleration technology characterised by extremely large (100s GV/m) accelerating fields and compact (~ cm) scale. Self-injection is a key mechanism in the production of electron beams from the laser wakefield accelerator (LWFA), where background plasma electrons spontaneously enter the accelerating field region. Self-injection is routinely exploited but a fully self-consistent model for the process is still lacking,as are reliable methods for the control of the self-injection process. In this thesis a model for control of self-injection using plasma density gradients or laser intensity evolution is presented. The model is validated using particle-in-cell (PIC) simulations and injection of sub-femtosecond electron bunches is demonstrated. This control is further exploited to demonstrate injection of a train of multiple electron bunches into the LWFA.An additional characteristic of the LWFA is the strong transverse focusing fields, which cause electrons to undergo betatron motion and emit broadband XUV and X-ray radiation. The previously demonstrated bunching is investigated as a source of tuneable coherent emission. Analytic and numerical models demonstrate coherent enhancement at the bunching wavelength. Finally the stability of the scheme is considered with respect to energy and spatial bunch spreads and found to be viable for tuneable XUV radiation production with current state of the art LWFA bunch parameters.
Author: Karl Schmid
Publisher: Springer Science & Business Media
ISBN: 364219950X
Category : Science
Languages : en
Pages : 169
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Book Description
This thesis covers the few-cycle laser-driven acceleration of electrons in a laser-generated plasma. This process, known as laser wakefield acceleration (LWFA), relies on strongly driven plasma waves for the generation of accelerating gradients in the vicinity of several 100 GV/m, a value four orders of magnitude larger than that attainable by conventional accelerators. This thesis demonstrates that laser pulses with an ultrashort duration of 8 fs and a peak power of 6 TW allow the production of electron energies up to 50 MeV via LWFA. The special properties of laser accelerated electron pulses, namely the ultrashort pulse duration, the high brilliance, and the high charge density, open up new possibilities in many applications of these electron beams.
Author: Jessica Shaw
Publisher:
ISBN:
Category :
Languages : en
Pages : 132
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Book Description
In this dissertation, the direct laser acceleration (DLA) of ionization-injected electrons in a laser wakefield accelerator (LWFA) operating in the quasi-blowout regime has been investigated through experiment and simulation. In the blowout regime of LWFA, the radiation pressure of an intense laser pulse can push a majority of the plasma electrons out and around the main body of the pulse. The expelled plasma electrons feel the electrostatic field of the relatively-stationary ions and are thus attracted back towards the laser axis behind the laser pulse where they overshoot the axis and set up a wake oscillation. When ionization injection is used, the inner-shell electrons of higher-Z dopant atoms are tunnel ionized near the peak of the laser pulse. Those electrons slip back relative to the wake until they gain enough energy from the longitudinal wakefield to become trapped. Those electrons that are trapped off-axis will undergo betatron oscillations in response to the linear transverse focusing force of the ions. Through experiments and supporting simulations, this dissertation demonstrates that when there is a significant overlap between the drive laser and the trapped electrons in a LWFA cavity, the accelerating electrons can gain energy from the DLA mechanism in addition to LWFA. When laser pulse overlaps the trapped electrons, the betatron oscillations of the electrons in the plane of the laser polarization can lead to an energy transfer from the transverse electric field of the laser to the transverse momentum of the electrons. This enhanced transverse momentum can then be converted into increased longitudinal momentum via the v x B force of the laser. This process is known as DLA. In this experimental work, the properties of the electron beams produced in a LWFA where the electrons are injected by ionization injection and become trapped without escaping the laser field have been investigated. The maximum measured energy of the produced electron beams scales with the overlap between the electrons and the laser. Undispersed electrons beams are observed to be elliptical in the plane of the laser polarization, and the energy spectrum splits into a fork at higher energies when the electrons beams are dispersed orthogonal to the direction of the laser polarization. These characteristic features are reproduced in particle-in-cell (PIC) code simulations where particle tracking was used to demonstrate that such spectral features are signatures of the presence of DLA in LWFA. Further PIC simulations comparing LWFA with and without DLA show that the presence of DLA can lead to electron beams that have maximum energies that exceed the estimates given by the theory for the ideal blowout regime. The magnitude of the contribution of DLA to the energy gained by the electron was found to be on the order of the LWFA contribution. In the LWFAs studied here, both DLA and LWFA participate in accelerating the bulk of the electrons in the produced electron beam. The presence of DLA in a LWFA can also lead to enhanced betatron oscillation amplitudes and increased divergence in the direction of the laser polarization.
Author: Xinlu Xu
Publisher: Springer Nature
ISBN: 9811523819
Category : Science
Languages : en
Pages : 138
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Book Description
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.
Author: Oliver Brning
Publisher: World Scientific
ISBN: 9814436402
Category : Science
Languages : en
Pages : 855
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Book Description
"The past 100 years of accelerator-based research have led the field from first insights into the structure of atoms to the development and confirmation of the Standard Model of physics. Accelerators have been a key tool in developing our understanding of the elementary particles and the forces that govern their interactions. This book describes the past 100 years of accelerator development with a special focus on the technological advancements in the field, the connection of the various accelerator projects to key developments and discoveries in the Standard Model, how accelerator technologies open the door to other applications in medicine and industry, and finally presents an outlook of future accelerator projects for the coming decades."--Provided by publisher.
Author: Deyun Li (M.A.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 84
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Book Description
Plasma-based wakefield accelerator is attractive for generating quasi-monoenergetic electron beams using the bubble regime. The bubble is formed by an intense driver, which propagates through the plasma and expels all electrons transversely, creating a cavity free of cold plasma electrons that trailing behind the driver. Self-injection is applicable in the bubble regime, which can produce bunches of quasi-monoenergetic electrons. (1) Such electron bunching structure can be diagnosed with coherent transition radiation and may be exploited to generate powerful high frequency radiation [16].This thesis focuses on electron bunching phenomenon through WAKE simulations and theoretical analysis. The simulation is completed under laser-driven field ionization wakefield acceleration. The code is improved by taking into consideration the high frequency property of laser driver in wakefield acceleration. Finer grid size is introduced to the ionization injection part of WAKE, for increasing simulation accuracy without much sacrifice of programming efficiency. Various conditions for optimal bunching in the trapped electrons are explored computationally and analytically.
Author: Paul Gibbon
Publisher: World Scientific
ISBN: 1911298844
Category : Science
Languages : en
Pages : 328
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Book Description
This book represents the first comprehensive treatment of the subject, covering the theoretical principles, present experimental status and important applications of short-pulse laser-matter interactions.Femtosecond lasers have undergone dramatic technological advances over the last fifteen years, generating a whole host of new research activities under the theme of “ultrafast science”. The focused light from these devices is so intense that ordinary matter is torn apart within a few laser cycles. This book takes a close-up look at the exotic physical phenomena which arise as a result of this new form of “light-matter” interaction, covering a diverse set of topics including multiphoton ionization, rapid heatwaves, fast particle generation and relativistic self-channeling. These processes are central to a number of exciting new applications in other fields, such as microholography, optical particle accelerators and photonuclear physics.Repository for numerical models described in Chapter 6 can be found at www.fz-juelich.de/zam/cams/plasma/SPLIM/./a
Author: Alex Chao
Publisher: World Scientific
ISBN: 9789810235000
Category : Science
Languages : en
Pages : 702
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Book Description
Edited by internationally recognized authorities in the field, this handbook focuses on Linacs, Synchrotrons and Storage Rings and is intended as a vade mecum for professional engineers and physicists engaged in these subjects. Here one will find, in addition to the common formulae of previous compilations, hard to find specialized formulae, recipes and material data pooled from the lifetime experiences of many of the world's most able practitioners of the art and science of accelerator building and operation.
Author: Grace Gloria Manahan
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Laser wakefield acceleration (LWFA) can occur when the ponderomotive force of high power ultra short laser pulses produce wakefields in underdense plasma. The structure of these wakefields are similar to those in rf cavities of conventional linear accelerators, but are characterised by large fields that can accelerate particles to high energies over much shorter distances. Compactness and inherent short bunch duration make LWFAs potential candidates for laboratory-scale coherent radiation sources. Currently, theoretical and experimental studies are being pursued to obtain in-depth understanding of LWFAs, in particular the injection mechanisms, as these will lead to better control and improved quality of the electron beams. Experimental effort is being directed towards the design of suitable diagnostics to measure the most important properties of the electron beam, one of which is the emittance. Emittance is a good figure of merit as it describes the beam distribution in phase space and provides information on the beam focusability. This work presents a numerical and experimental study of the potential of LWFA as a next generation table-top accelerator. The first part of the thesis investigates the transport of LWFA produced electron beams using conventional devices. To provide a "usable" beam, the transport system should be capable of preserving the transverse emittance. Possible sources of emittance growth are examined, focusing on the effects of energy spread, divergence and pointing stability on the emittance. The second part of the thesis presents direct single shot measurements of the transverse emittance using the pepper-pot technique. This method is also used to quantify the performance of high-gradient miniature permanent quadrupoles.
