Practical Formula for Laser Intensity at Beam Spray Onset

Coherent forward stimulated Brillouin scattering of a spatially incoherent laser beam in a plasma and its effect on beam spray

A statistical model for forward stimulated Brillouin scattering (FSBS) is developed for a spatially incoherent, monochromatic, laser beam propagating in a plasma. A threshold for the average power in a speckle is found, well below the self-focusing one, above which the laser beam spatial incoherence can not prevent the coherent growth of FSBS. Three-dimensional simulations confirm its existence and reveal the onset of beam spray above it. From these results, we propose a new figure of merit for the control of the propagation through a plasma of a spatially incoherent laser beam.

碰撞激光脉冲偏振对极端聚焦下$ e^{-}e^{+} $级联发展的影响

Effects of colliding laser pulses polarization on $ e^{-}e^{+} $ cascade development in extreme focusing

本研究针对极端聚焦下激光脉冲偏振影响电子-正电子级联启动的问题，发现径向偏振脉冲能让种子电子在峰值振幅时留存于焦平面，相比同参数圆/线偏振脉冲，可将级联启动所需激光功率降低100/80倍。

A Frenet-Serret Interpretation of Particle Dynamics in High-Intensity Laser Fields

In this paper we discuss the dynamics of charged particles in high-intensity laser fields in the context of the Frenet-Serret formalism, which describes the intrinsic geometry of particle worldlines. We find approximate relations for the Frenet-Serret scalars and basis vectors relevant for high-intensity laser particle interactions. The onset of quantum effects relates to the curvature radius of classical trajectories being on the order of the Compton wavelength. The effects of classical radiation reaction are discussed, as well as the classical precession of the spin-polarization vector accor…

Joule-level high effiency energy transfer to sub-picosecond laser pulses by a plasma-based amplifier

Laser plasma amplification of sub-picosecond pulses above the Joule level is demonstrated, a major milestone for this scheme to become a solution for the next-generation of ultra-high intensity lasers. By exploring over 6 orders of magnitude the influence of the incident seed intensity on Brillouin laser amplification, we reveal the importance of a minimum intensity to ensure an early onset of the self-similar regime, and a large energy transfer with a very high efficiency, up to 20%. Evidence of energy losses of the seed by spontaneous backward Raman is found at high amplification. The first …

Towards realistic simulations of QED cascades: non-ideal laser and electron seeding effects

A number of analytical and numerical studies has been performed to investigate the onset and the development of QED cascades in the collision of two counterpropagating laser pulses as a function of the laser intensity. However, it has been recently demonstrated [M. Tamburini et al., Sci. Rep. 7, 5694 (2017)] that the onset of QED cascades is also strongly influenced by the structure of the laser pulses, such as the laser pulse waist radius. Here we investigate how QED cascades are affected by: (a) the laser pulse duration, (b) the presence of a relative delay for the peak of the laser pulses t…

高Z等离子体中宽带激光驱动的受激布里渊散射研究

Investigation of Stimulated Brillouin Scattering Driven by Broadband Lasers in High-Z Plasmas

本研究通过一维碰撞粒子模拟探究高Z等离子体中宽带激光驱动的SBS演化，发现激光带宽超过SBS时间增长率数十倍时可有效抑制SBS，为惯性约束聚变宽带激光设计提供指导。