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Title: Enhancement of electron energy during vacuum laser acceleration in an inhomogeneous magnetic field

Abstract

In this paper, the effect of a stationary inhomogeneous magnetic field on the electron acceleration by a high intensity Gaussian laser pulse is investigated. A focused TEM (0,0) laser mode with linear polarization in the transverse x-direction that propagates along the z-axis is considered. The magnetic field is assumed to be stationary in time, but varies longitudinally in space. A linear spatial profile for the magnetic field is adopted. In other words, the axial magnetic field increases linearly in the z-direction up to an optimum point z{sub m} and then becomes constant with magnitude equal to that at z{sub m}. Three-dimensional single-particle simulations are performed to find the energy and trajectory of the electron. The electron rotates around and stays near the z-axis. It is shown that with a proper choice of the magnetic field parameters, the electron will be trapped at the focus of the laser pulse. Because of the cyclotron resonance, the electron receives enough energy from the laser fields to be accelerated to relativistic energies. Using numerical simulations, the criteria for optimum regime of the acceleration mechanism is found. With the optimized parameters, an electron initially at rest located at the origin achieves final energy of γ=802.more » The dynamics of a distribution of off-axis electrons are also investigated in which shows that high energy electrons with small energy and spatial spread can be obtained.« less

Authors:
;  [1]
  1. Department of Physics, Amirkabir University of Technology, 15875-4413 Tehran (Iran, Islamic Republic of)
Publication Date:
OSTI Identifier:
22408244
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 3; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ACCELERATION; COMPUTERIZED SIMULATION; CYCLOTRON RESONANCE; ELECTRONS; LASER RADIATION; LASERS; MAGNETIC FIELDS; POLARIZATION; PULSES; RELATIVISTIC RANGE; SPATIAL DISTRIBUTION; THREE-DIMENSIONAL CALCULATIONS; THREE-DIMENSIONAL LATTICES; TRAJECTORIES; TRANSMISSION ELECTRON MICROSCOPY; TRAPPING

Citation Formats

Saberi, H., and Maraghechi, B., E-mail: behrouz@aut.ac.ir. Enhancement of electron energy during vacuum laser acceleration in an inhomogeneous magnetic field. United States: N. p., 2015. Web. doi:10.1063/1.4916130.
Saberi, H., & Maraghechi, B., E-mail: behrouz@aut.ac.ir. Enhancement of electron energy during vacuum laser acceleration in an inhomogeneous magnetic field. United States. doi:10.1063/1.4916130.
Saberi, H., and Maraghechi, B., E-mail: behrouz@aut.ac.ir. Sun . "Enhancement of electron energy during vacuum laser acceleration in an inhomogeneous magnetic field". United States. doi:10.1063/1.4916130.
@article{osti_22408244,
title = {Enhancement of electron energy during vacuum laser acceleration in an inhomogeneous magnetic field},
author = {Saberi, H. and Maraghechi, B., E-mail: behrouz@aut.ac.ir},
abstractNote = {In this paper, the effect of a stationary inhomogeneous magnetic field on the electron acceleration by a high intensity Gaussian laser pulse is investigated. A focused TEM (0,0) laser mode with linear polarization in the transverse x-direction that propagates along the z-axis is considered. The magnetic field is assumed to be stationary in time, but varies longitudinally in space. A linear spatial profile for the magnetic field is adopted. In other words, the axial magnetic field increases linearly in the z-direction up to an optimum point z{sub m} and then becomes constant with magnitude equal to that at z{sub m}. Three-dimensional single-particle simulations are performed to find the energy and trajectory of the electron. The electron rotates around and stays near the z-axis. It is shown that with a proper choice of the magnetic field parameters, the electron will be trapped at the focus of the laser pulse. Because of the cyclotron resonance, the electron receives enough energy from the laser fields to be accelerated to relativistic energies. Using numerical simulations, the criteria for optimum regime of the acceleration mechanism is found. With the optimized parameters, an electron initially at rest located at the origin achieves final energy of γ=802. The dynamics of a distribution of off-axis electrons are also investigated in which shows that high energy electrons with small energy and spatial spread can be obtained.},
doi = {10.1063/1.4916130},
journal = {Physics of Plasmas},
number = 3,
volume = 22,
place = {United States},
year = {Sun Mar 15 00:00:00 EDT 2015},
month = {Sun Mar 15 00:00:00 EDT 2015}
}
  • Electron resonance acceleration by an intense laser pulse in an inhomogeneous external magnetic field is investigated. The acceleration mechanism makes use of electron cyclotron resonance to increase the electron energy. By appropriately tailoring the radial gradient of the magnetic field, an electron in the rising front part of laser pulse will be attracted toward the cyclotron-resonance radius and be trapped there, so that it can gain much energy. It is shown that the electron net energy gain can be up to the GeV level.
  • Laser-induced acceleration of an electron injected initially at an angle to the direction of a circularly polarized laser pulse in the presence of an obliquely incident magnetic field has been investigated. For a suitable position of the peak of the laser pulse, the external magnetic field exists at an angle such that it can be parallel to the magnetic field of the laser pulse. The electron gains considerable energy and retains it even after passing of the laser pulse in the presence of an optimum magnetic field in vacuum. The electron attains the maximum amount of energy at a particularmore » angle of the incident magnetic field due to the betatron resonance.« less
  • K. P. Singh [Phys. Rev. E 69, 056410 (2004)] put forward a scheme of vacuum laser acceleration in a static magnetic field. We point out that one of the assumptions used in their model does not stand on a solid physical ground and that it seriously influences electrons to obtain net energy gains from the laser field.
  • Hundred-mega-electron-volt electron beams with quasi-monoenergetic distribution, and a transverse geometrical emittance as small as approx0.02 pi mm mrad are generated by low power (7 TW, 45 fs) laser pulses tightly focused in helium gas jets in an external static magnetic field, Bapprox1 T. Generation of monoenergetic beams strongly correlates with appearance of a straight, at least 2 mm length plasma channel in a short time before the main laser pulse and with the energy of copropagating picosecond pedestal pulses (PPP). For a moderate energy PPP, the multiple or staged electron self-injection in the channel gives several narrow peaks in themore » electron energy distribution.« less
  • An experimental study of nonresonant electric-field enhancement and electron acceleration in a highly inhomogeneous subcritical plasma in the presence of a microwave source is reported. It is shown that it is possible to achieve an effective acceleration of electrons even with a nonresonant field enhancement which occurs when the conditions for plasma resonance (n/n sub c = 1) are not satisfied. 9 references.