激光偏振对激光尾场加速中Betatron X射线产生及角向收集的影响
Laser-Polarization Dependence of Betatron X-Ray Production and Angular Collection in Laser-Wakefield Acceleration
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中文总结 AI 辅助
研究激光偏振对尾场加速中betatron X射线产生及角向收集的影响，发现LP与CP在不同阶段和靶长下产额各异，LP后期优势因角向展宽而减弱，但整体中心光子更多，CP照明更均匀。
中文摘要 AI 辅助
激光偏振既影响betatron X射线的产生，也影响其角向分布，这两者共同决定了在固定角接收范围内收集到的光子产额。我们利用粒子云网格模拟，对等能量线偏振（LP）和圆偏振（CP）脉冲在两种不同长度的氦-氮靶中进行激光尾场加速，研究了这些效应。在较长靶中，CP在传播早期产生更多光子，而LP在后期产生更多。对于穿过2毫米铝的20-60 keV光子，在角选择前LP/CP产额比从早期的0.88变化到晚期的1.91。晚期发射的LP电子沿激光偏振方向发展出显著的横向振荡，并伴随辐射的角向展宽。这种展宽在很大程度上消除了LP在中心±5毫弧度接收范围内的后期产额优势，在此范围内两种产额几乎相等。然而，在整个相互作用过程中，LP提供更多的中心光子，而CP提供更均匀的照明。在较短靶中，高于100 MeV的提取电荷几乎相等，但通过四极子三重态输运，在350-500 MeV能带内、5毫米半径内，LP输送750 pC，CP输送500 pC。因此，收集到的光子和电子产额受传播长度和收集接收范围的影响。
英文摘要
Laser polarization affects both the production of betatron x rays and their angular distribution, which together determine the photon yield collected within a fixed angular acceptance. We investigate these effects using particle-in-cell simulations of laser-wakefield acceleration with linearly polarized (LP) and circularly polarized (CP) pulses of equal energy in helium--nitrogen targets of two different lengths. In the longer target, CP produces more photons early in propagation, whereas LP produces more later. For 20--60-keV photons transmitted through 2 mm of aluminum, the LP/CP yield ratio before angular selection changes from 0.88 early on to 1.91 in a late stage. Late-emitting LP electrons develop pronounced transverse oscillations along the laser polarization direction, accompanied by angular broadening of the radiation. This broadening largely removes the late LP production advantage within a central $\pm5$-mrad acceptance, where the two yields are nearly equal. Integrated over the full interaction, however, LP supplies more central photons, while CP provides more uniform illumination. In the shorter target, the extracted charges above 100 MeV are nearly equal, yet transport through a quadrupole triplet delivers 750 pC for LP and 500 pC for CP in the 350--500-MeV energy band within a radius of 5 mm. Collected photon and electron yields are thus shaped by propagation length and collection acceptance.
发表机构
- Extreme Light Infrastructure – Nuclear Physics (ELI-NP)（极轻基础设施-核物理研究所）
- Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH)（霍里亚·胡卢贝伊国家物理与核工程研发研究所）
- ELI Beamlines Facility, Extreme Light Infrastructure ERIC（极轻基础设施欧洲经济利益集团光束线设施）
机构由 AI 辅助整理，请以论文原文为准。
