Extended particle-in-cell schemes for physics in ultrastrong laser fields: Review and developments

Abstract

We review common extensions of particle-in-cell (PIC) schemes which account for strong field phenomena in laser-plasma interactions. After describing the physical processes of interest and their numerical implementation, we provide solutions for several associated methodological and algorithmic problems. We propose a modified event generator that precisely models the entire spectrum of incoherent particle emission without any low-energy cutoff, and which imposes close to the weakest possible demands on the numerical time step. Based on this, we also develop an adaptive event generator that subdivides the time step for locally resolving QED events, allowing for efficient simulation of cascades. Further, we present a new and unified technical interface for including the processes of interest in different PIC implementations. Two PIC codes which support this interface, PICADOR and ELMIS, are also briefly reviewed. CONTENTS

Spin-dependent radiative deflection in the quantum radiation-reaction regime

“…At each time step, the radiation probability rate  is calculated according to the local χ e value as well as the spin state. According to the QED-MC methods in [25], two uniform random numbers are generated in the [0, 1] section to sample the spectrum of the probability rate. The probability rate calculated with the first random number r 1 is multiplied with time step Δψ.…”

Classical and quantum particle dynamics in univariate background fields

“…Current approaches to solving (15) mimic that used in the plane wave case, by making the ansatz Φ ¼ e −ip:x Fðk:xÞ where p 2 ¼ m 2 [16,17]. With this the Klein-Gordon equation reduces to…”

“…The model is powerful but restrictive, being unable to account for effects due to the spatial geometry of a realistic laser pulse. This limits our ability to predict and analyze experimental results-indeed the primary source of phenomenological results for the complex interactions of focused laser fields with electron bunches and solid targets are PIC simulations, reviewed in [15].…”

Electronic parametric instabilities of an ultrarelativistic laser pulse in a plasma

“…It is instructive to examine the role of the radiationreaction (RR) force on the plasma dynamics in the ultrarelativistic regime of the laser-plasma interaction, which has been an active area of research in the last few years, especially with regards to the developments of QED-PIC codes [17][18][19]. In light of this, the effect of the RR force was included in the formalism of electronic parametric instabilities [16].…”