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Title: Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator

Abstract

Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator is investigated with a tomographic method which resolves the electron injection and acceleration processes. It is found that all the electrons in the monoenergetic electron bunch are injected at the same location in the plasma column and then accelerated with an acceleration gradient exceeding 2 GeV/cm. The injection position shifts with the position of pump-pulse focus, and no significant deceleration is observed for the monoenergetic electron bunch after it reaches the maximum energy. The results are consistent with the model of transverse wave breaking and beam loading for the injection of monoenergetic electrons. The tomographic method adds a crucial dimension to the whole array of existing diagnostics for laser beams, plasma waves, and electron beams. With this method the details of the underlying physical processes in laser-plasma interactions can be resolved and compared directly to particle-in-cell simulations.

Authors:
; ;  [1];  [1];  [2];  [3];  [1];  [2];  [2];  [1];  [2]
  1. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China)
  2. (China)
  3. Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan (China)
Publication Date:
OSTI Identifier:
21072407
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevE.75.036402; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 36 MATERIALS SCIENCE; ACCELERATION; BEAM BUNCHING; COMPUTERIZED SIMULATION; ELECTRON BEAM INJECTION; ELECTRON BEAMS; ELECTRONS; GEV RANGE; LASERS; PLASMA; PLASMA GUNS; PLASMA WAVES; PULSES; WAKEFIELD ACCELERATORS

Citation Formats

Chang, C.-L., Hsieh, C.-T., Ho, Y.-C., Chen, Y.-S., Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan, Lin, J.-Y., Wang, J., Department of Physics, National Central University, Jhong-Li 320, Taiwan, Department of Physics, National Taiwan University, Taipei, 106, Taiwan, Chen, S.-Y., and Department of Physics, National Central University, Jhong-Li 320, Taiwan. Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator. United States: N. p., 2007. Web. doi:10.1103/PHYSREVE.75.036402.
Chang, C.-L., Hsieh, C.-T., Ho, Y.-C., Chen, Y.-S., Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan, Lin, J.-Y., Wang, J., Department of Physics, National Central University, Jhong-Li 320, Taiwan, Department of Physics, National Taiwan University, Taipei, 106, Taiwan, Chen, S.-Y., & Department of Physics, National Central University, Jhong-Li 320, Taiwan. Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator. United States. doi:10.1103/PHYSREVE.75.036402.
Chang, C.-L., Hsieh, C.-T., Ho, Y.-C., Chen, Y.-S., Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan, Lin, J.-Y., Wang, J., Department of Physics, National Central University, Jhong-Li 320, Taiwan, Department of Physics, National Taiwan University, Taipei, 106, Taiwan, Chen, S.-Y., and Department of Physics, National Central University, Jhong-Li 320, Taiwan. Thu . "Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator". United States. doi:10.1103/PHYSREVE.75.036402.
@article{osti_21072407,
title = {Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator},
author = {Chang, C.-L. and Hsieh, C.-T. and Ho, Y.-C. and Chen, Y.-S. and Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan and Lin, J.-Y. and Wang, J. and Department of Physics, National Central University, Jhong-Li 320, Taiwan and Department of Physics, National Taiwan University, Taipei, 106, Taiwan and Chen, S.-Y. and Department of Physics, National Central University, Jhong-Li 320, Taiwan},
abstractNote = {Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator is investigated with a tomographic method which resolves the electron injection and acceleration processes. It is found that all the electrons in the monoenergetic electron bunch are injected at the same location in the plasma column and then accelerated with an acceleration gradient exceeding 2 GeV/cm. The injection position shifts with the position of pump-pulse focus, and no significant deceleration is observed for the monoenergetic electron bunch after it reaches the maximum energy. The results are consistent with the model of transverse wave breaking and beam loading for the injection of monoenergetic electrons. The tomographic method adds a crucial dimension to the whole array of existing diagnostics for laser beams, plasma waves, and electron beams. With this method the details of the underlying physical processes in laser-plasma interactions can be resolved and compared directly to particle-in-cell simulations.},
doi = {10.1103/PHYSREVE.75.036402},
journal = {Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics},
number = 3,
volume = 75,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • Via three-dimensional particle-in-cell simulations, the self-mode-transition of a laser-driven electron acceleration from laser wakefield to plasma-wakefield acceleration is studied. In laser wakefield accelerator (LWFA) mode, an intense laser pulse creates a large amplitude wakefield resulting in high-energy electrons. Along with the laser pulse depletion, the electron bunch accelerated in the LWFA mode drives a plasma wakefield. Then, after the plasma wakefield accelerator mode is established, electrons are trapped and accelerated in the plasma wakefield. The mode transition process and the characteristics of the accelerated electron beam are presented.
  • In this paper, we present results on a scalable high-energy electron source based on laser wakefield acceleration. The electron accelerator using 30-80 TW, 30 fs laser pulses, operates in the blowout regime, and produces high-quality, quasi-monoenergetic electron beams in the range 100-800 MeV. These beams have angular divergence of 1-4 mrad, and 5%-25% energy spread, with a resulting brightness 10{sup 11} electrons mm{sup -2} MeV{sup -1} mrad{sup -2}. The beam parameters can be tuned by varying the laser and plasma conditions. The use of a high-quality laser pulse and appropriate target conditions enables optimization of beam quality, concentrating a significantmore » fraction of the accelerated charge into the quasi-monoenergetic component.« less
  • In laser wakefield acceleration, tailoring the shape of the laser pulse is one way of influencing the laser-plasma interaction and, therefore, of improving the quality of the self-injected electron beam in the bubble regime. Using three-dimensional particle-in-cell simulations, the evolution dynamics of the laser pulse and the quality of the self-injected beam, for a Gaussian pulse, a positive skew pulse (i.e., one with sharp rise and slow fall), and a negative skew pulse (i.e., one with a slow rise and sharp fall) are studied. It is observed that with a negative skew laser pulse there is a substantial improvement inmore » the emittance (by around a factor of two), and a modest improvement in the energy-spread, compared to Gaussian as well as positive skew pulses. However, the injected charge is less in the negative skew pulse compared to the other two. It is also found that there is an optimal propagation distance that gives the best beam quality; beyond this distance, though the energy increases, the beam quality deteriorates, but this deterioration is least for the negative skew pulse. Thus, the negative skew pulse gives an improvement in terms of beam quality (emittance and energy spread) over what one can get with a Gaussian or positive skew pulse. In part, this is because of the lesser injected charge, and the strong suppression of continuous injection for the negative skew pulse.« less
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  • The effect of laser-focusing conditions on the evolution of relativistic plasma waves in laser-wakefield accelerators is studied both experimentally and with particle-in-cell simulations. For short focal-length (w{sub 0}<{lambda}{sub p}) interactions, beam breakup prevents stable propagation of the pulse. High field gradients lead to nonlocalized phase injection of electrons, and thus broad energy spread beams. However, for long focal-length geometries (w{sub 0}>{lambda}{sub p}), a single optical filament can capture the majority of the laser energy and self-guide over distances comparable to the dephasing length, even for these short pulses (c{tau}{approx_equal}{lambda}{sub p}). This allows the wakefield to evolve to the correct shapemore » for the production of the monoenergetic electron bunches, as measured in the experiment.« less