arXiv subjects

Christoffer Olofsson

Publications and source records attributed to Christoffer Olofsson.

4 recordsLinked to original sources

arXiv2025

$\pi$-PIC: a framework for modular particle-in-cell developments and simulations

Particle-in-cell (PIC) codes are indispensable tools for studying plasma-based interactions across a wide range of physical regimes. The predictive capabilities of these codes have dramatically increased by continuous advances in algorithms and computing hardware. Nevertheless, greater computational performance and broader framework capabilities often lead to increased software complexity, hindering the adoption, evaluation, and comparison of new numerical developments. In this work, we present a Python-controlled framework designed to facilitate the dissemination and adoption of novel PIC developments by providing a unified interface for accommodation, cross-testing, and comparison of PIC algorithms. To demonstrate the flexibility of the proposed interface, we implement and discuss a range of PIC schemes together with applications involving absorbing boundary layers, moving-window simulations, and tight laser focusing.

physics.plasm-ph↗

arXiv2023

Prospects for statistical tests of strong-field quantum electrodynamics with high-intensity lasers

Exploiting high-energy electron beams colliding into high-intensity laser pulses brings an opportunity to reach high values of the dimensionless rest-frame acceleration $χ$ and thereby invoke processes described by strong-field quantum electrodynamics (SFQED). Measuring deviations from the results of perturbative SFQED at high $χ$ can be valuable for testing the existing predictions, as well as for guiding further theoretical developments. Nevertheless such experimental measurements are challenging due to the probabilistic nature of the interaction processes, a strong background produced by low-$χ$ interactions and limited capabilities to control and measure the alignment and synchronization in such collision experiments. Here we elaborate a methodology of using approximate Bayesian computations (ABC) for retrieving statistically justified inferences based on the results of many repeated experiments even in case of partially unknown collision parameters that vary from experiment to experiment. As a proof of principles, we consider the problem of inferring the effective mass change due to coupling with strong-field environment.

physics.plasm-ph↗

arXiv2022

Attaining a strong-field QED signal at laser-electron colliders with optimized focusing

Colliding bunches of high-energy electrons with intense laser pulses provides a basis for studying strong-field QED processes enabled by high values of quantum non-linearity parameter $χ$. Nevertheless, the signal deconvolution is intricate due to probabilistic nature of the processes and shot-to-shot variation of the impact parameter, which disfavors the use of tight focusing. We propose a concept for distinguishing the signal of high-$χ$ emissions that enables the use of optimal focusing to attain the highest $χ\approx 5.25 \left(\varepsilon / (\text{1 GeV})\right)\left(P/(\text{1 PW})\right)^{1/2}\left((\text{1 }μ\text{m})/λ\right)$ for a given electron energy $\varepsilon$, laser power $P$ and wavelength $λ$. Reaching such $χ$ with f/2 focusing requires more than 10 times higher power.

physics.plasm-ph↗

arXiv2020

Laser wakefield driven generation of isolated CEP-tunable intense sub-cycle pulses

Sources of intense, ultra-short electromagnetic pulses enable applications such as attosecond pulse generation, control of electron motion in solids and the observation of reaction dynamics at the electronic level. For such applications both high-intensity and carrier envelope phase~(CEP) tunability are beneficial, yet hard to obtain with current methods. In this work we present a new scheme for generation of isolated CEP-tunable intense sub-cycle pulses with central frequencies that range from the midinfrared to the ultraviolet. It utilizes an intense laser pulse which drives a wake in a plasma, co-propagating with a long-wavelength seed pulse. The moving electron density spike of the wake amplifies the seed and forms a sub-cycle pulse. Controlling the CEP of the seed pulse, or the delay between driver and seed leads to CEP-tunability, while frequency tunability can be achieved by adjusting the laser and plasma parameters. Our 2D and 3D Particle-In-Cell simulations predict laser-to-sub-cycle-pulse conversion efficiencies up to 1%, resulting in relativistically intense sub-cycle pulses.

physics.optics↗