Dense electron-positron plasmas and bursts of gamma-rays from laser-generated quantum electrodynamic plasmas

Abstract

In simulations of a 12.5PW laser (focussed intensity I = 4×10 23 Wcm −2 ) striking a solid aluminum target 10% of the laser energy is converted to gamma-rays. A dense electron-positron plasma is generated with a maximum density of 10 26 m −3 ; seven orders of magnitude denser than pure e − e + plasmas generated with 1PW lasers. When the laser power is increased to 320PW (I = 10 25 Wcm −2 ) 40% of the laser energy is converted to gamma-ray photons and 10% to electron-positron pairs. In both cases there is strong feedback between the QED emission processes and the plasma physics; the defining feature of the new 'QED-plasma' regime reached in these interactions.

Radiation-Reaction Trapping of Electrons in Extreme Laser Fields

“…A most foreseeable effect is that electrons lose a considerable amount of energy by emitting photons in the laser field, namely the radiation reaction (RR) effect [11]. Particle-incell (PIC) simulations suggest that γ photons may become the dominant energy absorption channel and even take more energy than electrons [7][8][9]. As a result, the relativistic motion of electrons at these laser intensities is strongly modified [12,13].…”

“…At this intensity level, the laser-plasma interaction will be prompted to the exotic near-QED regime [4][5][6][7][8][9][10]. A most foreseeable effect is that electrons lose a considerable amount of energy by emitting photons in the laser field, namely the radiation reaction (RR) effect [11].…”

Radiating electron source generation in ultraintense laser-foil interactions

“…Here, E s = mc 2 /eλ c is the Schwinger field [22] with λ c = /mc the reduced Compton length. For χ e 0.5 the stochastic nature of photon emission becomes important, meaning that a radiating electron emits fewer photons per emission, compared to the classical radiation dominated regime [17,23,24]. For χ e ∼ 1, the quantum nature of the radiation, with emitted photons having energy comparable to the electron energy, leads to discontinuous particle trajectories with significant recoils and non-negligible electron-positron pair creation [25][26][27][28][29].…”

The Lagrangian formulation of strong-field quantum electrodynamics in a plasma

“…In such a case G remains zero and F = −a 2 m ph 2 /2. The presence of a strong laser field with intensity corresponding to χ > 1, ξ ≫ 1 stimulates a mechanism called QED cascade [8][9][10][11] . During the cascade, an electron is accelerated by the laser field, absorbs many laser photons and emits a gamma photon through a quantum process called the nonlinear Compton scattering.…”

“…Nowadays, the kinetic calculation of QED cascades is based on a Monte Carlo technique describing the quantum processes, integrated with Particle-In-Cell codes taking into account the collective electromagnetic field influence on the classical motion of the electrons 8,9,11 . The rates embedded in the Monte Carlo routine rely on the assumption that the electromagnetic field invariants vanish.…”