Post-acceleration of protons in helical coil targets driven by intense, ultrashort laser pulses can enhance ion energy by utilizing the transient current from the targets’ self-discharge. The acceleration length of protons can exceed a few millimeters, and the acceleration gradient is of the order of GeV/m. How to ensure the synchronization between the accelerating electric field and the protons is a crucial problem for efficient post-acceleration. In this paper, we study how the electric field mismatch induced by current dispersion affects the synchronous acceleration of protons. We propose a scheme using a two-stage helical coil to control the current dispersion. With optimized parameters, the energy gain of protons is increased by four times. Proton energy is expected to reach 45 MeV using a hundreds-of-terawatts laser, or more than 100 MeV using a petawatt laser, by controlling the current dispersion.

In this work, the high-energy-density plasmas (HEDP) evolved from joule-class-femtosecond-laser-irradiated nanowire-array (NWA) targets were numerically and experimentally studied. The results of particle-in-cell simulations indicate that ions accelerated in the sheath field around the surfaces of the nanowires are eventually confined in a plasma, contributing most to the high energy densities. The protons emitted from the front surfaces of the NWA targets provide rich information about the interactions that occur. We give the electron and ion energy densities for broad target parameter ranges. The ion energy densities from NWA targets were found to be an order of magnitude higher than those from planar targets, and the volume of the HEDP was several-fold greater. At optimal target parameters, 8% of the laser energy can be converted to confined protons, and this results in ion energy densities at the GJ/cm³ level. In the experiments, the measured energy of the emitted protons reached 4 MeV, and the changes in energy with the NWA’s parameters were found to fit the simulation results well. Experimental measurements of neutrons from ²H(d,n)³He fusion with a yield of (24 ± 18) × 10⁶/J from deuterated polyethylene NWA targets also confirmed these results.

流动的无支撑液体薄膜在各个领域有着广泛应用。超强激光作用在这样的薄膜上，可产生涵盖太赫兹到伽马射线的高亮度次级辐射及高能的离子，并具有高重频、低成本、可连续工作等显著优势。概述了液体薄膜靶的制备和表征方法，阐明了液体薄膜靶相对于传统靶材的特性和优势，并对其在激光驱动辐射源和激光离子加速中的应用做出了总结和展望。

The results of a commissioning experiment on the SILEX-Ⅱ laser facility (formerly known as CAEP-PW) are reported. SILEX-Ⅱ is a complete optical parametric chirped-pulse amplification laser facility. The peak power reached about 1 PW in a 30 fs pulse duration during the experiment. The laser contrast was better than 10¹⁰ at 20 ps ahead of the main pulse. In the basic laser foil target interaction, a set of experimental data were collected, including spatially resolved x-ray emission, the image of the coherent transition radiation, the harmonic spectra in the direction of reflection, the energy spectra and beam profile of accelerated protons, hot-electron spectra, and transmitted laser energy fraction and spatial distribution. The experimental results show that the laser intensity reached 5 × 10²⁰ W/cm² within a 5.8 µm focus (FWHM). Significant laser transmission did not occur when the thickness of the CH foil was equal to or greater than 50 nm. The maximum energy of the accelerated protons in the target normal direction was roughly unchanged when the target thickness varied between 50 nm and 15 µm. The maximum proton energy via the target normal sheath field acceleration mechanism was about 21 MeV. We expect the on-target laser intensity to reach 10²² W/cm² in the near future, after optimization of the laser focus and upgrade of the laser power to 3 PW.

基于超短超强激光的短脉冲中子源是实现超快中子探测的理想中子源。如何提升中子产额是目前短脉冲激光中子源实现应用需求亟需解决的关键问题。提出基于靶背鞘场加速机制和束靶反应方案，采用LiD复合组分靶作为中子转换体，可以有效提升激光中子产额。与常规的LiF转换体相比，除了p-Li和d-Li两个反应道之外，LiD转换体可以多出p-D和d-D两个反应道，因此可充分利用激光加速的质子和氘离子的多反应通道优势来提升中子产生概率。实验结果表明，相比于LiF转换体，LiD转换体可带来中子产额2～3倍的提升，达到5.2×10⁸ n/sr的最高中子产额，并具备更好的前冲性。实验还区分了多反应通道的贡献，证明中子产额提升主要来自于p-D反应。

Carbon nanotube foams (CNFs) have been successfully used as near-critical-density targets in the laser-driven acceleration of high-energy ions and electrons. Here we report the recent advances in the fabrication technique of such targets. With the further developed floating catalyst chemical vapor deposition (FCCVD) method, large-area ($>25\kern0.5em {\mathrm{cm}}^2$) and highly uniform CNFs are successfully deposited on nanometer-thin metal or plastic foils as double-layer targets. The density and thickness of the CNF can be controlled in the range of $1{-}13\kern0.5em \mathrm{mg}/{\mathrm{cm}}^3$ and $10{-}200\kern0.5em \mu \mathrm{m}$, respectively, by varying the synthesis parameters. The dependence of the target properties on the synthesis parameters and the details of the target characterization methods are presented for the first time.

针对线性传输算法中透射率和大气光估计不足问题，提出一种基于线性模型的自适应优化去雾算法。利用边缘信息模型来增强初始透射率图的细节信息，使得复原后图像边缘区域细节更丰富；根据暗通道先验，得到自适应优化透射率，更好地处理包含景深区域图像；采用局部大气光估计方法代替四叉树方法，避免大气光估计不准确问题，并结合物理模型恢复图像。仿真实验在matlab2014中进行，实验结果表明，该算法具有较好的有效性和时效性。

氧化铀不仅是重要的核材料, 也是潜在的多功能材料。UO₂晶体具有优异的半导体性能和抗辐照能力, 其禁带宽度(1.3 eV)与Si(1.1 eV)相近, 塞贝克系数是常用热电材料BiTe的4倍, 对太阳光的全吸收使其成为高效的太阳能电池材料, 在半导体、太阳能和热电等领域具有巨大的应用潜力。但是UO₂随着环境变化会出现从缺氧到过氧的价态变化(UO_2±x, x= -0.5~1), 即超化学计量比特性, 给材料制备和性能控制等方面带来很多问题。本文从相图出发, 总结了各种铀氧化物的结构及其稳定性, 重点聚焦UO₂晶体的研究进展。理想化学计量比UO₂被认为是最好的Mott绝缘体, 其电导率是相对稳定的; 超化学计量比氧化铀则具有半导体特性, 其电导率、热导率、扩散系数以及光学性能都与x密切相关。目前, UO₂晶体生长主要采用化学气相输运法(CVT)、冷坩埚法、水热法、升华法、助熔剂法等, 晶体尺寸和质量还不理想, 冷坩埚法和水热法被认为是最有潜力的生长技术。氧化铀单晶生长研究不仅有助于深入了解UO₂材料特性, 也为其在太阳能电池、热电器件以及未来电子学领域的应用提供可能性。