Study of Relativistic Electrons Generated from Ultra-intense Laser-Plasma Interaction relevant to Laser Wakefield Acceleration and Fast Ignition Laser Fusion Open Access
- Other title
Fast Electron transport
Laser Wakefield Acceleration
Ultra-intense laser-plasma interaction
- Type of item
- Degree grantor
University of Alberta
- Author or creator
- Supervisor and department
Robert Fedosejevs (ECE)
- Examining committee member and department
Ying Tsui (ECE)
Vien Van (ECE)
Richard Sydora (Physics)
Karl Krushelnick(Univ. Michigan, Physics Dept.)
Rambabu Karumudi (ECE)
Department of Electrical and Computer Engineering
Photonics and Plasmas
- Date accepted
- Graduation date
Doctor of Philosophy
- Degree level
Ultra-intense (> 10^18 W/cm^2) laser interaction with matter is capable of producing relativistic electrons which have a variety of applications in scientific and medical research. Knowledge of various aspects of these hot electrons is important in harnessing them for various applications. Of particular interest for this thesis is the investigation of hot electrons generated in the areas of Laser Wakefield Acceleration (LWFA) and Fast Ignition (FI).
LWFA is a physical process in which electrons are accelerated by the strong longitudinal electrostatic fields that are formed inside the plasma cavities or wakes produced by the propagation of an ultra-intense laser pulse through an under-dense plasma. The accelerating E-fields inside the cavities are 1000 times higher than those of conventional particle accelerators and can accelerate electrons to the relativistic regime in a very short distance, on the order of a few millimeters. In addition, Betatron X-ray radiation can be produced from LWFA as a result of the transverse oscillations of the relativistic electrons inside the laser wakefield driven cavity. The pulse duration of Betatron radiation can be as short as a few femtoseconds, making it an ideal probe for measuring physical phenomena taking place on the time scale of femtoseconds. Experimental research on the electron acceleration of the LWFA has been conducted in this thesis and has led to the generation of mono-energetic electron bunches with peak energies ranging from a few hundreds of MeV to 1 GeV. In addition, the Betatron radiation emitted from LWFA was successfully characterized based on a technique of reflection off a grazing incidence mirror. Furthermore, we have developed a Betatron X-ray probe beamline based on the technique of K-shell absorption spectroscopy to directly measure the temporal evolution of the ionization states of warm dense aluminum. With this, we have achieved for the first time direct measurements of the ionization states of warm dense aluminum using Betatron X-ray radiation probing.
Fast Ignition (FI) is an advanced scheme for inertial confinement fusion (ICF), in which the fuel ignition process is decoupled from its compression. Comparing with the conventional central hot-spot scheme for ICF, FI has the advantages of lower ignition threshold and higher gain. The success of FI relies on efficient energy coupling from the heating laser pulse to the hot electrons and subsequent transport of their energy to the compressed fuel. As a secondary part of this thesis, the transport of hot electrons in overdense plasma relevant to FI was studied. In particular, the effect of resistive layers within the target on the hot electron divergence and absorption was investigated. Experimental measurements were carried out and compared to simulations indicating minimal effect on the beam divergence but some attenuation through higher atomic number intermediate layers was observed.
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
- Citation for previous publication
P. E. Masson-Laborde, M. Z. Mo, A. Ali, S. Fourmaux, P. Lassonde, J. C. Kieffer, W. Rozmus, D. Teychenne, and R. Fedosejevs, Phys. Plasmas 21, 123113 (2014).M. Z. Mo, A. Ali, S. Fourmaux, P. Lassonde, J. C. Kieffer, and R. Fedosejevs, Appl. Phys. Lett. 100, 074101 (2012).M. Z. Mo, A. Ali, S. Fourmaux, P. Lassonde, J. C. Kieffer, and R. Fedosejevs, Appl. Phys. Lett. 102, 134102 (2013).M. Z. Mo, A. Ali, S. Fourmaux, P. Lassonde, J. C. Kieffer, and R. Fedosejevs, Eur. Phys. J. D 68, 301 (2014).M. Z. Mo, Z. Chen, S. Fourmaux, A. Saraf, K. Otani, J. C. Kieffer, Y. Y. Tsui, A. Ng and R. Fedosejevs, Rev. Sci. Instrum. 84, 123106 (2013).
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