Kinetic modelling of quantum effects in laser-beam interaction

We present the results of kinetic modelling of quantum effects in laser-beam interaction. In the developed numerical model, electron-positron pair production by hard photons, hard photon emission and the electromagnetic fields generated by the created charged particles are taken into account. Interaction of a relativistic electron beam with a strong laser pulse is analyzed. It is shown that the quantum effects can be important even for moderately intense laser pulses when the number of emitted photons by single electron is not large. Electron-positron pair plasma production in extremely-intense laser field via development of electromagnetic cascades is also studied. The simulation results confirm the prediction of strong laser field absorption in the self-generated electron-positron plasma. It is shown that the self-generated electron-positron plasma can be an efficient source of energetic gamma-quanta.Comment: Submitted to Nuclear Instruments and Methods in Physics Research

Growth rate of QED cascades in a rotating electric field

QED cascading in a rotating electric field is studied. The cascade growth rate is derived from kinetic equations for electron-positron pairs and photons as a function of the field strength. The rate is in an agreement with the results of numerical simulations of QED cascade.Досліджено розвиток квантово-електродинамічного (КЕД) каскаду в обертаючому електричному полі. З кінетичних рівнянь для електрон-позитронних пар та фотонів виведено інкремент зростання каскаду як функція напруженості поля. Отримана формула збігається з результатами числового моделювання.Исследовано развитие квантово-электродинамического (КЭД) каскада во вращающемся электрическом поле. Из кинетических уравнений для электрон-позитронных пар и фотонов выведен инкремент роста каскада как функция напряженности поля. Полученная формула согласуется с результатами численного моделирования

Synchrotron radiation losses in laser-plasma accelerators

Like in conventional accelerators, a synchrotron radiation can significantly suppress an acceleration in a bubble. The dynamics of accelerating electron in the bubble with consideration of the synchrotron radiation reaction force is studied. The total suppression of electron acceleration by the radiation losses is discussed.Как и в случае традиционных ускорителей, потери, связанные с синхротронным излучением, могут существенно снизить эффективность ускорения. В работе исследована динамика электрона в ионной полости с учетом действия силы реакции синхротронного излучения. Обсуждается полное подавление ускорения электронов радиационными потерями.Як й у випадку традиційних прискорювачів, втрати, пов'язані із синхротронним випромінюванням, можуть істотно знизити ефективність прискорення. У роботі досліджена динаміка електрона в іонній порожнині з урахуванням дії сили реакції синхротронного випромінювання. Обговорюється повне придушення прискорення електронів радіаційними втратами

Short-term evolution of electron wave packet in a constant crossed field with radiative corrections

International audienceWe study the dynamics of an electron wave packet in a strong constant crossed electromagnetic field with account for radiative corrections due to interaction of the electron with the vacuum fluctuations. We evaluate a wave packet composed of the solutions to the Dyson-Schwinger equation, which describes electron propagation without emission of real photons. Spacetime dependence of the wave packet is obtained analytically for a short time interval, the more restricted from above the wider is the packet in momentum space. The radiative corrections alter the electron wavefunction, resulting in particular in a damping of the wave packet. The expectation value of the Dirac spin operator also gets modified

Short-term evolution of electron wave packet in a constant crossed field with radiative corrections

International audienceWe study the dynamics of an electron wave packet in a strong constant crossed electromagnetic field with account for radiative corrections due to interaction of the electron with the vacuum fluctuations. We evaluate a wave packet composed of the solutions to the Dyson-Schwinger equation, which describes electron propagation without emission of real photons. Spacetime dependence of the wave packet is obtained analytically for a short time interval, the more restricted from above the wider is the packet in momentum space. The radiative corrections alter the electron wavefunction, resulting in particular in a damping of the wave packet. The expectation value of the Dirac spin operator also gets modified

Near QED regime of laser interaction with overdense plasmas

Interaction of laser plulses with intensities up to 1025 W/cm2 with overdense plasma targets is investigated via three-dimensional particle-in-cell simulations. At these intensities, radiation of electrons in the laser field becomes important. Electrons transfer a significant fraction of their energy to γ-photons and obtain strong feedbacks due to radiation reaction (RR) force. The RR effect on the distribution of laser energies among three main species: electrons, ions and photons is studied. The RR and electron-positron pair creation are implemented by a QED model. As the laser intensity inreases, the ratio of laser energy coupled to electrons drops while the one for γ-photons reaches up to 35%. Two distinctive plasma density regimes of the high-density carbon target and low-density solid hydrogen target are identified from the laser energy partitions and angular distributions of photons. The power-laws of absorption efficiency versus laser intensity and the transition of photon divergence are revealed. These show enhanced generation of γ-photon beams with improved collimation in the relativistically transparent regime. A new effect of transverse trapping of electrons inside the laser field caused by the RR force is observed: electrons can be unexpectedly confined by the intense laser field when the RR force is comparable to the Lorentz force. Finally, the RR effect and different regions of photon emission in laser-foil interactions are clarified

New horizons for extreme light physics with mega-science project XCELS

A short review of the Russian mega-science project XCELS and scientific problems to be solved are presented. We discuss the origin of multi-beam design to attain the highest field magnitude at optimal focusing. Then, we formulate particular physical problems of fundamental interest that can be solved within this project