AI 中文总结
本研究在LMJ装置开发激光尾场加速平台，利用PETAL激光产生超1μC、500 MeV的电子束及焦耳级光子束，为高电荷电子束应用及高能量密度物质探测提供了新途径。
AI 中文摘要
我们在LMJ装置上报道了超高电荷相对论电子束的产生及激光尾场加速平台的开发。利用千焦耳级、亚皮秒的PETAL激光脉冲聚焦于超声氦气喷流，产生了总电荷超过1μC、能量达约500 MeV的电子束。鉴于皮秒级激光脉冲持续时间、接近10^19 W/cm²的靶面强度以及达到临界密度2%的等离子体密度，电子加速源于自调制激光尾场加速（SMLWFA）与直接激光加速（DLA）的结合。所得电子谱呈现麦克斯韦型分布，是SMLWFA/DLA混合机制的特征。该电子束携带的总能量估计可达17 J，持续时间小于1 ps。通过轫致辐射还产生了宽带焦耳级光子束，证明了其未来应用潜力。实验结果得到了从首到尾的数值模拟支持，包括三维粒子模拟与蒙特卡罗粒子输运计算。这些发现为需要高电荷电子束的应用铺平了道路，包括高功率次级辐射或粒子源的产生；利用这些电子束探测由纳秒级LMJ束驱动的高能量密度物质，是另一个有前景的方向。
英文摘要
We report on the production of ultrahigh-charge relativistic electron beams and the development of a laser-wakefield acceleration platform at the LMJ facility. Making use of the kilojoule-class, sub-picosecond PETAL laser pulse focused onto a supersonic helium gas jet, electron beams carrying a total charge beyond 1 $μ$C were generated, with energies up to $\sim$500 MeV. Given the ps-scale laser pulse duration, an on-target intensity approaching $10^{19}~\mathrm{W/cm^2}$, and a plasma density reaching 2% of the critical density, electron energisation arises from a combination of self-modulated laser wakefield acceleration (SMLWFA) and direct laser acceleration (DLA). The resulting electron spectrum exhibits a Maxwellian-like distribution, characteristic of this mixed SMLWFA/DLA regime. The total energy carried by the electron beam is estimated to be up to 17 J, within a sub-ps duration. A broadband Joule-level photon beam was also produced by Bremsstrahlung, demonstrating the potential for future applications. Experimental results are supported by start-to-end numerical simulations, including 3-D particle-in-cell and Monte-Carlo particle transport calculations. These findings pave the way for applications requiring high-charge electron beams, including the generation of high-power secondary radiation or particle sources. The use of these beams to probe matter in high-energy density states driven by the nanosecond-duration LMJ beams represents another promising avenue.
