Seeded QED cascades in counterpropagating laser pulses

Grismayer, Thomas; Vranić, Marija; Martins, Joana; Fonseca, Ricardo; Silva, L. O.

doi:10.1103/physreve.95.023210

Cited by 137 publications

(153 citation statements)

References 39 publications

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“…In the interactions of ultra-high intensity laser pulses with matter we can expect particle acceleration over compact, micron-scale, regions [16], extremely intense bursts of γ-ray emission [44] and the creation of dense pair-plasmas [37]. Here we have shown that it is possible to select into which species the laser energy is coupled by the choice of target density and thickness.…”

Section: Discussionmentioning

confidence: 77%

“…with the electron Lorentz factor γ e and the QED parameter η (the electric field strength in the electronʼs rest frame relative to the critical field of QED E crit =4.3×10 13 G [51]) assumed constant in time and computed as described in equation (6) of [52], accounting for the Gaunt factor associated with QED photon emission. Γ(η) is the rate of the exponential density growth as given in equation (10) of [37]. In addition we account for the fact that the field inside the target is reduced due to the skin effect in the relativistically overcritical plasma by correcting the intensity as follows: I SD =I γ e n c /(γ HB n 0 ) [44].…”

Section: Zn V Imentioning

confidence: 99%

“…the density at which its dynamics will strongly affect the propagation of the laser pulse [34,35]. In fact this pair-plasma may absorb the laser pulse [36][37][38]. Consequently, the energy of the accelerated ions is strongly reduced.…”

Section: Introductionmentioning

confidence: 99%

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Efficient ion acceleration and dense electron–positron plasma creation in ultra-high intensity laser-solid interactions

et al. 2018

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The radiation pressure of next generation ultra-high intensity (>10 23 W cm −2 ) lasers could efficiently accelerate ions to GeV energies. However, nonlinear quantum-electrodynamic effects play an important role in the interaction of these laser pulses with matter. Here we show that these effects may lead to the production of an extremely dense (∼10 24 cm −3 ) pair-plasma which absorbs the laser pulse consequently reducing the accelerated ion energy and laser to ion conversion efficiency by up to 30%-50% and 50%-65%, respectively. Thus we identify the regimes of laser-matter interaction, where either ions are efficiently accelerated to high energy or dense pair-plasmas are produced as a guide for future experiments.

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Section: Discussionmentioning

confidence: 77%

Section: Zn V Imentioning

confidence: 99%

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Efficient ion acceleration and dense electron–positron plasma creation in ultra-high intensity laser-solid interactions

et al. 2018

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“…Laser-induced electron-positron cascades have been previously investigated for various laser intensities, targets and laser pulse shapes (e.g. [3,4,7,10]). The dynamics of cascades are complicated and in general analytical solutions are unattainable.…”

Section: Identifying the Cascade Regimesmentioning

confidence: 99%

Identifying the electron–positron cascade regimes in high-intensity laser-matter interactions

2019

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Strong-field quantum electrodynamics predicts electron-seeded electron-positron pair cascades when the electric field in the rest-frame of the seed electron approaches the Sauter-Schwinger field, i.e. h =Ẽ E 1 S RF . Electrons in the focus of next generation multi-PW lasers are expected to reach this threshold. We identify three distinct cascading regimes in the interaction of counter-propagating, circularly-polarised laser pulses with a thin foil by performing a comprehensive scan over the laser intensity (from 10 23 to 5×10 24 W cm −2 ) and initial foil target density (from 10 26 to 10 31 m −3 ). For low densities and intensities the number of pairs grows exponentially. If the intensity and target density are high enough the number density of created pairs reaches the relativistically-corrected critical density, the pair plasma efficiently absorbs the laser energy (through radiation reaction) and the cascade saturates. If the initial density is too high, such that the initial target is overdense, the cascade is suppressed by the skin effect. We derive a semi-analytical model which predicts that dense pair plasmas are endemic features of these interactions for intensities above 10 24 W cm −2 provided the target's relativistic skin-depth is longer than the laser wavelength. Further, it shows that pair production is maximised in near-critical-density targets, providing a guide for near-term experiments.S RF . We can reach η∼1 for laser fields much weaker than E S as the fields themselves can rapidly accelerate electrons to high Lorentz factor, resulting in a strong Lorentz boost to E RF . Pair production by the multi-photon Breit-Wheeler process can occur if the photons emitted during Compton scattering satisfy a similar condition on their quantum efficiency parameter (defined below) χ∼1. An electromagnetic cascade can ensue if many generations of electrons and positrons can be generated by the fields. Usually this occurs via a two-step process whereby the electrons and positrons produced by the Breit-Wheeler process radiate photons by nonlinear Compton scattering which subsequently decay to further pairs and so on.Upcoming facilities, like several of those comprising the extreme light infrastructure (ELI) [1,2], are expected to reach laser intensities of > -

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“…Recent three dimensional simulations have also allowed to determine the conditions for electromagnetic cascades with ELI scale lasers [15], including the radiation signatures and the properties of the associated gamma ray source, and the dependence of these processes on the configurations of the laser, taking into account the polarization or multi-beam configurations.…”

Section: Exploring Extreme Plasma Conditions In the Lab And In Astropmentioning

confidence: 99%

“Boiling the vacuum”: in silico plasmas under extreme conditions in the laboratory and in astrophysics

Silva¹

2017

Europhysics News

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Laser technology has progressed tremendously since Theodore Maiman first demonstrated the laser in 1960. One of the most striking examples of this progress is the focused intensity of lasers. Present day lasers in the near infrared frequency range can deliver intensities in excess of 10 23 W/cm 2 . Imagine that you have a very large and powerful lens that captures the light of the sun hitting the upper atmosphere of the Earth and focus it down to a region with the cross section of a human hair. The corresponding intensity is in the range of the most intense lasers now available.EPN 48/5&6 35 bOILING THE VAcUUM FEATURES start to be important. A single ultra relativistic electron quivering in an ultra intense laser field can radiate x-rays. As the intensity is ramped up, the electron oscillating in the laser field will radiate gamma-rays. These gamma-rays can, in turn, interact with the laser and generate electron-positron pairs which, in the presence of the laser field, can again radiate strongly. An electromagnetic cascade of pairs and gamma-rays is then triggered, generating a quantum electrodynamic (QED) electron-positron plasma.It is also possible to conceive scenarios where a static (or slowly varying) ultra strong electric field is present in a finite region of space. Let us imagine the field is so strong that, as the electron is accelerated over the distance of a Compton wavelength it gains more than 2 m e c 2 , i.e. the rest mass energy of an electron and a positron. In this case, an electron-positron pair is generated, which will then interact with the ultra strong field itself, and a cascading process can also be triggered. The critical electric field for pair creation in vacuum, first identified by Sauter, is called the Schwinger critical field E s = 2 π m e 2 c 3 /e h, where e is the electron charge, m e the electron mass, h is the Planck constant, and c the speed of light. For extreme field physics a common used dimensionless parameter is χ = E/E s , where E represents the electric field in the rest frame of the electron. χ determines the transition from the classical to the quantum dynamics; for χ on the order or higher than unity, QED effects are important and must be considered. Colloquially, when copious amounts of electrons and positrons are produced by ultra strong electromagnetic fields in vacuum, or via a cascade from a low density seed of electrons, the "vacuum is boiling".The prospect to reach in the laboratory these conditions in the near future is triggering many exciting developments [7,8] at the cross roads of nonperturbative QED, plasma physics, and astrophysics. In many extreme astrophysical objects (e.g. pulsars, magnetars, or in the magnetosphere U nder the action of these intense electromagnetic fields, electrons quiver at velocities close to the speed of light with Lorentz gamma factors ~100. The nonlinear effects associated with special relativity determine the evolution of light-plasma interactions at these intensities. These lasers are now being explored to drive plasma acceler...

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Seeded QED cascades in counterpropagating laser pulses

Cited by 137 publications

References 39 publications

Efficient ion acceleration and dense electron–positron plasma creation in ultra-high intensity laser-solid interactions

Efficient ion acceleration and dense electron–positron plasma creation in ultra-high intensity laser-solid interactions

Identifying the electron–positron cascade regimes in high-intensity laser-matter interactions

“Boiling the vacuum”: in silico plasmas under extreme conditions in the laboratory and in astrophysics

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