Author: Marko von der LeyenPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Study of Novel Electron Injection Mechanisms for Laser-wakefield Accelerators
Author: Marko von der LeyenControl of Electron Injection and Acceleration in Laser-Wakefield Accelerators
Author: Emilien GuillaumeStudies of Transverse Properties of Relativistic Electrons from Laser Wakefield Accelerator
Author: Grace Gloria ManahanPublisher:
ISBN:
Category :
Languages : en
Pages : 0
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.
Self Injection and Radiation Production in Laser Wakefield Accelerators
Author: Matthew Philip TooleyPublisher:
ISBN:
Category :
Languages : en
Pages : 0
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.
Phase Space Dynamics in Plasma Based Wakefield Acceleration
Author: Xinlu XuPublisher: Springer Nature
ISBN: 9811523819
Category : Science
Languages : en
Pages : 138
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.
LASER WAKEFIELD ACCELERATION BEYOND 1 GeV USING IONIZATION INDUCED INJECTION*
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 7
Book Description
A series of laser wake field accelerator experiments leading to electron energy exceeding 1 GeV are described. Theoretical concepts and experimental methods developed while conducting experiments using the 10 TW Ti:Sapphire laser at UCLA were implemented and transferred successfully to the 100 TW Callisto Laser System at the Jupiter Laser Facility at LLNL. To reach electron energies greater than 1 GeV with current laser systems, it is necessary to inject and trap electrons into the wake and to guide the laser for more than 1 cm of plasma. Using the 10 TW laser, the physics of self-guiding and the limitations in regards to pump depletion over cm-scale plasmas were demonstrated. Furthermore, a novel injection mechanism was explored which allows injection by ionization at conditions necessary for generating electron energies greater than a GeV. The 10 TW results were followed by self-guiding at the 100 TW scale over cm plasma lengths. The energy of the self-injected electrons, at 3 x 1018 cm−3 plasma density, was limited by dephasing to 720 MeV. Implementation of ionization injection allowed extending the acceleration well beyond a centimeter and 1.4 GeV electrons were measured.
Generation, Acceleration and Measurement of Attosecond Electron Beams from Laser-plasma Accelerators
Author: Maria Katharina WeikumExperimental Study of Laser-driven Electron and Proton Acceleration
Author: Salima AbuazoumPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
This thesis addresses two important topics in the field of laser-driven plasma accelerators. Firstly, the research investigates the generation of relativistic electron beams through laser-wakefield acceleration (LWFA) by applying novel tapered capillary discharge waveguide accelerators, produced by femtosecond laser micromachining. A stable plasma waveguide is formed in a hydrogen-filled capillary driven by an all-solid state high-voltage pulser, specially constructed for this purpose. A longitudinal density taper has been confirmed by measurement of the transverse plasma density profiles at both ends of the waveguide and efficient guiding of low intensity (~1012 W/cm2), ultra-short duration (50 fs) laser pulses is demonstrated. For optimal high-power laser conditions (intensity of 1.6 x 1018 W/cm2), electron beams are produced and compared in positively tapered, negatively tapered and straight capillaries with similar plasma densities of 3-6 x 1018 cm-3 over a length of 4 cm. In all three capillaries, low charge (
An Exploration on Electron Bunching of Ionization Induced Self-injection in Laser Wakefield Accelerators
Author: Deyun Li (M.A.)Publisher:
ISBN:
Category :
Languages : en
Pages : 84
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.
Controlled Electron Injection Into Plasma Accelerators and SpaceCharge Estimates
Author: Gwenael J. FubianiPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Plasma based accelerators are capable of producing electron sources which are ultra-compact (a few microns) and high energies (up to hundreds of MeVs) in much shorter distances than conventional accelerators. This is due to the large longitudinal electric field that can be excited without the limitation of breakdown as in RF structures. The characteristic scale length of the accelerating field is the plasma wavelength and for typical densities ranging from 1018 - 1019 cm-3, the accelerating fields and scale length can hence be on the order of 10-100GV/m and 10-40 mu m, respectively. The production of quasimonoenergetic beams was recently obtained in a regime relying on self-trapping of background plasma electrons, using a single laser pulse for wakefield generation. In this dissertation, we study the controlled injection via the beating of two lasers (the pump laser pulse creating the plasma wave and a second beam being propagated in opposite direction) which induce a localized injection of background plasma electrons. The aim of this dissertation is to describe in detail the physics of optical injection using two lasers, the characteristics of the electron beams produced (the micrometer scale plasma wavelength can result in femtosecond and even attosecond bunches) as well as a concise estimate of the effects of space charge on the dynamics of an ultra-dense electron bunch with a large energy spread.