分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Laser-plasma instability (LPI) is one of the main obstacles in laser-driven inertial confinement fusion (ICF) for achieving predictable and reproducible fusion at high gain. For the first time we have proved analytically and confirmed with three-dimensional particle-in-cell simulations that angular incoherence has additional and much stronger suppression of the instability growth rate than the well-known temporal incoherence and spatial incoherence usually used in ICF studies. For the model used in our calculations, the maximum field ratio between the stimulated Raman scattering and the driving pulses drops from 0.2 for the Laguerre-Gaussian pulse with a single non-zero topological charge to 0.05 for the super light spring with an angular momentum spread and random relative phases. In particular, angular incoherence does not introduce extra undesirable hot electrons. This opens a novel way to suppress LPI with the light of an angular momentum spread and paves the way towards a low LPI laser system with a super light spring of incoherence in all dimensions of time, space, and angle.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Relativistic vortex particles offer a promising avenue for investigating and manipulating processes in high-energy and nuclear physics, as they provide an additional degree of freedom in the form of orbital-angular-momentum (OAM). Despite the potential benefits, the generation and detection of these particles have proven to be a significant challenge. In this work, we present a new method for producing high-energy vortex electrons and $\gamma$-photons by colliding relativistic electrons with circularly polarized laser pulses in the radiation-dominated quantum electrodynamics (QED) regime. We use the laser-dressed vortex state to develop a nonlinear scattering theory, which allows us to understand the transfer of spin angular momenta (SAM) to intrinsic OAM in the highly nonlinear multi-photon process. The theory shows that electrons in the vortex state carry higher intrinsic OAM when radiation-reaction becomes significant, with the central OAM number proportional to the amount of energy taken by the $\gamma$-photon. This study provides an effective approach to generating high-energy vortex electron beams using laser intensities that are currently achievable. Additionally, the emission spectra of energetic electrons in vortex states are found to exhibit multi-peaks, which sets them apart from plane-wave electrons and makes them easier to distinguish.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The hypothetical axion and axion-like particles, feebly coupled with photon, have not yet been found in any experiment. With the improvement of laser technique, much stronger but shorter quasi-static electric and magnetic fields can be created in laboratory using laser-plasma interaction, compared to the fields of large magnets, to help the search of axion. In this article, we discuss the feasibility of ALPs exploration using planarly or cylindrically symmetric laser-plasma fields as background and an x-ray free-electron laser as probe. Both the probe and the background fields are polarized such that the existence of ALPs in the corresponding parameter space will cause polarization rotation of the probe, which can be detected with high accuracy. Besides, a structured field in the plasma creates a tunable transverse profile for the interaction and improves the signal-to-noise ratio via phase-matching mechanism. The ALP mass discussed in this article ranges from $10^{-3}$ eV to 1 keV. Some simple schemes and estimations on ALP production and polarization rotation of probe photon are given, which reveals the possibility of future laser-plasma ALP source in laboratory.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： High energy photons can be generated via inverse Compton scattering (ICS) in the collision between energetic electrons and intense laser pulse. The development of laser plasma accelerators promises compact and all-optical gamma-ray sources by colliding the electrons from laser wakefield accelerators to its high-power driving pulse reflected by a plasma mirror. However, the law of optical focusing hinders realization of both high photon yield and monochromatic spectrum in this scenario. We propose an azimuthal spatial-temporal convertor that decouples the focal field strength from laser spot size using helical parabolic geometry. It decomposes the driving laser beam into a pulse train of almost identical divergence angle and focal depth, creating synchronized ICS in the optimized linear regime. The scheme resolves the dilemma between high efficiency and narrow energy spread, facilitating the generation of monochromatic gamma-ray using high power lasers beyond relativistic field strengths.
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