Relativistic Particle Motion in Nonuniform Electromagnetic Waves

Schmidt, G.; Wilcox, T. J.

doi:10.1103/physrevlett.31.1380

Cited by 20 publications

(12 citation statements)

References 9 publications

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“…26. However, our results are consistent with earlier derivations, 28,29 using different approachs to the equations of motion. Further, our results are consistent in the fluid limit with those published in Ref.…”

Section: ͑A35͒supporting

confidence: 92%

Kinetic modeling of intense, short laser pulses propagating in tenuous plasmas

1997

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Fast time averaged equations are derived for the motion of particles and the generation of electromagnetic wake fields under the action of the ponderomotive potential of an ultraintense laser pulse propagating through a tenuous plasma. Based on these averaged equations, a new particle code is designed which calculates the particle trajectories on the plasma period time scale. The regime of total cavitation of the plasma is investigated. It is found that stable propagation over a long distance is possible in this regime, and that energetic electrons are produced with a simple characteristic dependence of their angle of deflection on energy. This new code allows for computationally efficient modeling of pulse propagation over great distances.

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Section: ͑A35͒supporting

confidence: 92%

Kinetic modeling of intense, short laser pulses propagating in tenuous plasmas

1997

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“…Electron acceleration by intense laser fields in plasmas has been the subject attracting a great deal of attention recently due to the advent of high power laser pulses and their potential applications. Various acceleration mechanisms have been proposed, including the plasma wave acceleration [1,2], the direct laser acceleration [3][4][5], and the mixed acceleration from both the transverse and the longitudinal fields [6,7].…”

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confidence: 99%

Stochastic Heating and Acceleration of Electrons in Colliding Laser Fields in Plasma

et al. 2002

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We propose a mechanism that leads to efficient acceleration of electrons in plasma by two counterpropagating laser pulses. It is triggered by stochastic motion of electrons when the laser fields exceed some threshold amplitudes, as found in single-electron dynamics. It is further confirmed in particle-in-cell simulations. In vacuum or tenuous plasma, electron acceleration in the case with two colliding laser pulses can be much more efficient than with one laser pulse only. In plasma at moderate densities, such as a few percent of the critical density, the amplitude of the Raman-backscattered wave is high enough to serve as the second counterpropagating pulse to trigger the electron stochastic motion. As a result, even with one intense laser pulse only, electrons can be heated up to a temperature much higher than the corresponding laser ponderomotive potential.

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“…When averaged over several cycles, this typically results in a drift motion where electrons are isotropically expelled away from high intensity regions, an effect which can be accounted for by the relativistic ponderomotive force [20][21][22].…”

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confidence: 99%

“…Indeed, in order to stay in phase with the laser field, electrons need to have initial velocities close to c along the laser propagation axis. In addition, they should start interacting with the intense laser beam already close to its spatial and temporal maxima, and even be injected at appropriate phases of this field.Electrons that do not satisfy these stringent requirements tend to explore many different optical cycles as they interact with the laser field, leading to an oscillatory motion where they are successively accelerated and decelerated, so that their final energy gain is low.When averaged over several cycles, this typically results in a drift motion where electrons are isotropically expelled away from high intensity regions, an effect which can be accounted 2 for by the relativistic ponderomotive force [20][21][22].Here, we present clear evidence of vacuum laser acceleration of bunches of ∼ 10 10 electrons, corresponding to charges in the nC range, up to relativistic energies around 10 MeV.Our experimental results clearly discriminate for the first time electrons that have experienced a quasi-monotonic sub-laser-cycle acceleration, from those whose dynamics has mostly been determined by ponderomotive scattering. To solve the long-standing experimental problem of electron injection in the laser field, we demonstrate a new approach based on the use of plasma mirrors [23], that specularly reflect ultraintense laser fields while simultaneously injecting relativistic electrons in the core of these reflected fields, co-linearly to the propagation direction.…”

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confidence: 99%

Vacuum laser acceleration of relativistic electrons using plasma mirror injectors

et al. 2015

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Accelerating particles to relativistic energies over very short distances using lasers has been a long standing goal in physics. Among the various schemes proposed for electrons, vacuum laser acceleration has attracted considerable interest and has been extensively studied theoretically because of its appealing simplicity: electrons interact with an intense laser field in vacuum and can be continuously accelerated, provided they remain at a given phase of the field until they escape the laser beam. But demonstrating this effect experimentally has proved extremely challenging, as it imposes stringent requirements on the conditions of injection of electrons in the laser field. Here, we solve this long-standing experimental problem for the first time by using a plasma mirror to inject electrons in an ultraintense laser field, and obtain clear evidence of vacuum laser acceleration.With the advent of PetaWatt class lasers, this scheme could provide a competitive source of very high charge (nC) and ultrashort relativistic electron beams.1 arXiv:1511.05936v1 [physics.plasm-ph] 18 Nov 2015Femtosecond lasers currently achieve light intensities at focus that far exceed 10 18 W/cm 2 at near infrared wavelengths [1]. One of the great prospects of these extreme intensities is the laser-driven acceleration of electrons to relativistic energies within very short distances.At present, the most advanced scheme consists of using ultraintense laser pulses to excite large amplitude wakefields in underdense plasmas, providing extremely high accelerating gradients in the order of 100 GV/m [2]. However, over the past decades, the direct acceleration of electrons by light in vacuum has also attracted considerable interest and has been extensively studied theoretically [3][4][5][6][7][8][9][10][11]. These investigations have been driven by the fundamental interest of this most elementary interaction, and by its potential for extreme electron acceleration through electric fields of > 10's TV/m that ultraintense laser pulses provide.The underlying idea is to inject free electrons into an ultraintense laser field so that they always remain within a given half optical cycle of the field, where they constantly gain energy until they leave the focal volume. 1D Analytical calculations [3] show that for relativistic electrons, the maximum energy gain from this process is ∆E ∝ mc 2 γ 0 a 2 0 , where γ 0 is the electron initial Lorentz factor, and a 0 is the normalized laser vector potential, m the electron mass, and c the vacuum light velocity. Reaching high energy gains thus requires high initial energies γ 0 1 and/or ultrahigh laser amplitudes (a 0 1).In contrast with the large body of theoretical work published on this vacuum laser acceleration (VLA) of electrons to relativistic energies, experimental observations have largely remained elusive [12][13][14][15][16][17] -sometimes even controversial [18,19]-and have so far not demonstrated significant energy gains. This is because VLA occurs efficiently only for electrons injected in t...

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Relativistic Particle Motion in Nonuniform Electromagnetic Waves

Cited by 20 publications

References 9 publications

Kinetic modeling of intense, short laser pulses propagating in tenuous plasmas

Kinetic modeling of intense, short laser pulses propagating in tenuous plasmas

Stochastic Heating and Acceleration of Electrons in Colliding Laser Fields in Plasma

Vacuum laser acceleration of relativistic electrons using plasma mirror injectors

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