arXiv subjects

Xue-Ren Hong

Publications and source records attributed to Xue-Ren Hong.

5 recordsLinked to original sources

arXiv2026

High-charge, highly polarized positron beams generated from a laser-driven nanowire-array target

The generation of high-charge, highly polarized positron beams in the interaction of a linearly polarized laser pulse with a nanowire-array target is investigated. Here, laser-driven electrons emit high-energy photons through nonlinear Compton scattering (NCS), which subsequently produce electron--positron pairs through the nonlinear Breit--Wheeler (NBW) process. We model this interaction using two-dimensional spin-resolved quantum electrodynamics particle-in-cell (QED-PIC)} simulations. At positron birth, the sign of $S_z$ is statistically correlated with that of the local $B_z$. The spatiotemporal field structure arising from the laser--nanowire interaction strengthens the correlation between the birth spin sign and the direction of the subsequent transverse Lorentz impulse, thereby limiting cancellation between opposite-spin contributions at a given angle. The results show that the average polarization degree reaches $|\bar S_z|\approx0.46$, and the positron charge satisfying $|\bar S_z|>0.3$ is approximately $308\,\mathrm{nC}$. Parameter scans reveal that the high-polarization positron charge is maximized at intermediate target densities and nanowire periods. Such a source could enable polarization-sensitive studies of strong-field QED and spin-dependent phenomena in high-energy and materials physics.

physics.plasm-ph↗

arXiv2026

Polarization-resolved attosecond gamma-ray emission from few-cycle laser interactions with cone targets

Linearly polarized attosecond $\gamma$-ray pulses in the MeV range are generated from a cone target irradiated by a single few-cycle laser pulse. Electron layers are periodically extracted from the cone walls and subsequently accelerated. Their interaction with the counter-propagating reflected attosecond field produces high-energy photons through nonlinear Compton scattering (NCS), forming attosecond $\gamma$-ray pulses. We model this interaction using two-dimensional quantum electrodynamics particle-in-cell (QED-PIC) simulations that resolve electron spin and photon polarization during emission. The results show a shortest equivalent duration of $300\,\mathrm{as}$, with a corresponding linear polarization degree of 0.78. The photon spectrum extends to $6\,\mathrm{MeV}$, and the linear polarization degree in the high-energy range reaches 0.88. The linear polarization degree remains high when photons from both emission directions are collected over wide momentum-angle ranges. Scans over the cone opening angle and the coupled laser-plasma parameters reveal tradeoffs among photon number, mean photon energy, and polarization. Such highly polarized attosecond $\gamma$-ray pulses could be used to investigate ultrafast nuclear dynamics and polarization-dependent processes in strong-field quantum electrodynamics.

physics.plasm-ph↗

arXiv2026

Electron-positron pair production in spatially inhomogeneous electric fields with quadratically symmetric chirp

Electron-positron pair production from vacuum in spatially inhomogeneous electric fields with quadratically symmetric chirp is studied within the real-time Dirac-Heisenberg-Wigner formalism. The reduced momentum spectrum and the reduced total number of the created particles under the quadratically symmetric chirped electric field are investigated in high- and low-frequency fields. Compared with that of the quadratically asymmetric chirped field in particular, it is found that the momentum spectrum under the quadratically symmetric chirped field exhibits the stronger oscillations and the higher peaks in both high- and low- frequency fields, and it shows an obvious widening only in the high-frequency field. It is also found that the total number of the created particles of the quadratically symmetric chirped field increases with the chirp, and it is nearly twice that of the quadratically asymmetric chirped field.

hep-ph↗

arXiv2025

Effect of super-Gaussian pulse shape on pair production in chirped electric field with spatial inhomogeneity

Pair production in spatially inhomogeneous chirped electric fields with super-Gaussian pulse shape is investigated using the Dirac-Heisenberg-Wigner formalism, and the effect of super-Gaussian pulse shapes on the reduced momentum spectrum and the reduced total yield of created particles is mainly concerned. It is found that with the variation of the super-Gaussian envelope exponent, the momentum spectrum exhibits the more pronounced oscillations, shifting and broadening. The total yield of created particles increases monotonically with the increase of the super-Gaussian envelope exponent in the high-frequency fields with small chirp and low-frequency fields with any chirp. Meanwhile, the total yield of created particles under the super-Gaussian pulse electric fields is approximately twice that produced with the usual Gaussian pulse envelope. These results can provide theoretical guidance for optimizing the form of external field to enhance the vacuum pair production rate.

hep-ph↗

arXiv2017

Enhanced laser radiation pressure acceleration of protons with a gold cone-capillary

A scheme with gold cone-capillary is proposed to improve the protons acceleration and involved problems are investigated by using the two-dimensional particle-in-cell simulations. It is demonstrated that the cone-capillary can efficiently guide and collimate the protons to a longer distance and lead to a better beam quality with a dense density $\geq10n_c$, monoenergetic peak energy $E_k \sim 1.51~\mathrm{GeV}$, spatial emittance $\sim0.0088~\mathrm{mm}~\mathrm{mrad}$ with divergence angle $θ\sim 1.0^{\circ}$ and diameter $\sim 0.5\mathrm{μm}$. The enhancement is mainly attributed to the focusing effect by the transverse electric field generated by the cone as well as the capillary, which can prevent greatly the protons from expanding in the transverse direction. Comparable to without the capillary, the protons energy spectra have a stable monoenergetic peak and divergence angle near to $1.0^{\circ}$ in longer time. Besides, the efficiency of acceleration depending on the capillary length is explored, and the optimal capillary length is also achieved. Such a target may be benefit to many applications such as ions fast ignition in inertial fusion, proton therapy in medicine and so on.

physics.plasm-ph↗