arXiv subjects

Aodhan McIlvenny

Publications and source records attributed to Aodhan McIlvenny.

3 recordsLinked to original sources

arXiv2026

Fundamental limit of intensity scaling for harmonic generation on plasma mirrors

Plasma mirrors have the potential to considerably boost the intensity of ultra-intense laser pulses through high-order harmonic generation, offering a promising route to the extreme fields required for probing the strong-field regime of quantum electrodynamics (SF-QED). This prospect relies on the favorable scaling of harmonic generation with increasing laser intensity, a longstanding assumption that has remained untested at extreme intensities. Combining the first measurements of Doppler harmonic generation approaching $10^{22}\,\mathrm{W/cm^2}$ with advanced particle-in-cell modeling, our study reveals fundamental limitations to this scaling. We notably observe a strong reduction of the harmonic yield as the laser intensity is increased, and show using simulations that this originates from the interaction of the sub-picosecond laser pedestal with the plasma mirror. This pedestal drives a rapid evolution of the plasma surface, through radiation-pressure compression and surface modulations, which progressively suppress harmonic generation. By extending our simulations up to intensities of $10^{23}\,\mathrm{W/cm^2}$, we show that this evolution accelerates strongly with increasing intensity, eventually leading to plasma mirror disruption on the timescale of the main laser pulse itself, making pulse duration, in addition to temporal contrast, a second key parameter for efficient harmonic generation. These results reveal the fundamental limits of the intensity scaling of harmonic generation from plasma mirrors and establish the conditions required to preserve efficient harmonic generation at extreme intensities, providing critical guidance for their use as intensity boosters toward the SF-QED regime.

physics.plasm-ph↗

arXiv2026

Limitations of post accelerating ion beams using the snowplow field in a near-critical density target

Laser-matter interaction at relativistic intensities is central to almost every scientific case for multi-PW laser facilities. In particular, the progress in laser-driven ion acceleration brings this interaction closer to multiple applications, ranging from material science to biomedical research. One of the most important questions regarding ion acceleration is how to obtain high charge ion beams with relativistic energies. Increasing laser energy and intensity usually leads to a number of limitations on maximum achievable ion energies rooted in the fundamental properties of charged particle interaction with strong electromagnetic fields. Following advances in staged laser-plasma electron acceleration, staged ion acceleration could offer a path to relativistic energies. Here, such scheme is explored and the possibility of scaling the acceleration of ion beams to relativistic energies is discussed.

physics.plasm-ph↗

arXiv2021

Spectrally peaked proton beams shock accelerated from an optically shaped overdense gas jet by a near-infrared laser

We report on the generation of impurity-free proton beams from an overdense gas jet driven by a near-infrared laser ($λ_L=1.053$ $\mathrmμ m$). The gas profile was shaped prior to the interaction using a controlled prepulse. Without this optical shaping, a 30$\pm$4 nCsr$^{-1}$ thermal spectrum was detected transversely to the laser propagation direction with a high energy 8.27$\pm$7 MeV, narrow energy spread (6$\pm$2 %) bunch containing 45$\pm$7 pCsr$^{-1}$. In contrast, with optical shaping the radial component was not detected and instead forward going protons were detected with energy 1.32$\pm$2 MeV, 12.9$\pm$3 % energy spread, and charge 400$\pm$30 pCsr$^{-1}$. Both the forward going and radial narrow energy spread features are indicative of collisionless shock acceleration of the protons.

physics.plasm-ph↗