Author Affiliations
1 State Key Laboratory of Nuclear Physics and Technology, and Key Laboratory of HEDP of the Ministry of Education, CAPT, Peking University, Beijing, China
2 Beijing Laser Acceleration Innovation Center, Beijing, China
3 Institute of Guangdong Laser Plasma Technology, Guangzhou, China
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.
current dispersion helical targets laser-driven ions synchronous post-acceleration 
High Power Laser Science and Engineering
2023, 11(4): 04000e51
Author Affiliations
1 State Key Laboratory of Nuclear Physics and Technology, and Key Laboratory of HEDP of the Ministry of Education, CAPT, School of Physics, Peking University, Beijing 100871, China
2 Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
3 Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE), Institute of Modern Physics, Fudan University, Shanghai 200433, China
4 School of Nuclear Science and Technology, University of South China, Hengyang 421001, China
5 INPAC and School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
6 Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
7 Institute of Experimental and Applied Physics, Czech Technical University in Prague, Husova 240/5, 11000 Prague 1, Czech Republic
8 ELI Beamlines Center, Institute of Physics of the Czech Academy of Sciences, 252 41 Dolní Břežany, Czechia
9 Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA
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.
Matter and Radiation at Extremes
2022, 7(6): 064403
Author Affiliations
1 State Key Laboratory of Nuclear Physics and Technology, and Key Laboratory of HEDP of the Ministry of Education CAPT Peking University Beijing 100871 China
2 Hebei Key Laboratory of Compact Fusion Langfang 065001 China
3 ENN Science and Technology Development Co., Ltd. Langfang 065001 China
4 Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China
5 School of Nuclear Science and Technology University of South China Hengyang 421001 China
6 Beijing Laser Acceleration Innovation Center Huairou Beijing 101400 China
7 Institute of Guangdong Laser Plasma Technology Baiyun Guangzhou 510540 China
Here, we report the generation of MeV alpha-particles from H-11B fusion initiated by laser-accelerated boron ions. Boron ions with maximum energy of 6 MeV and fluence of 109/MeV/sr@5 MeV were generated from 60 nm-thick self-supporting boron nanofoils irradiated by 1 J femtosecond pulses at an intensity of 1019 W/cm2. By bombarding secondary hydrogenous targets with the boron ions, 3 × 105/sr alpha-particles from H-11B fusion were registered, which is consistent with the theoretical yield calculated from the measured boron energy spectra. Our results demonstrated an alternative way toward ultrashort MeV alpha-particle sources employing compact femtosecond lasers. The ion acceleration and product measurement scheme are referential for the studies on the ion stopping power and cross section of the H-11B reaction in solid or plasma.
Laser and Particle Beams
2022, 2022(3): 5733475
彭梓洋 1,2曹正轩 1,2高营 1,2陈式有 1,2[ ... ]马文君 1,2,*
1 北京大学 核物理与核技术国家重点实验室,北京 100871
2 北京激光加速创新中心,北京 101407
液体薄膜 激光驱动辐射源 激光离子加速 高重频 liquid film laser-driven radiation source laser-drive ion acceleration high repetition-rate 
2022, 34(8): 081003
1 北京大学核物理与核技术国家重点实验室, 北京 100871
2 西北核技术研究所激光与物质相互作用国家重点实验室, 陕西 西安 710024
3 北京激光加速创新中心, 北京 101407
4 北京大学应用物理与技术研究中心, 北京 100871

飞秒激光作用于等离子体可以产生短脉宽、高亮度的极紫外(EUV)辐射,在高分辨率成像、时间分辨谱学等方面都有潜在的应用。为进一步提高辐射亮度,利用相对论飞秒激光与碳纳米管泡沫(CNF)靶相互作用实现了高转换效率的EUV辐射。实验结果表明,当激光能量为1.2 J,CNF密度为4 mg/cm 3时,单发产生的EUV辐射光谱强度在0.1 mJ·nm -1·sr -1量级。相比高密度固体靶,采用低密度CNF靶可以有效地提高激光吸收率,进而实现两个量级的EUV辐射效率增益。同时发现,基于CNF的EUV辐射在15~30 nm波长范围内具有准连续的宽谱特征,适合于超快吸收光谱等应用。

X射线光学 极紫外辐射 飞秒激光 碳纳米管泡沫 宽谱辐射 X-ray optics extreme-ultraviolet radiation femtosecond laser carbon nanotube foams continuum radiation 
2022, 42(11): 1134021
Author Affiliations
1 Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, CAEP, Mianyang, Sichuan Province 621900, China
2 Institute of Applied Physics and Computational Mathematics, Beijing 100871, China
3 Institute of Heavy Ion Physics, Peking University, Beijing 100871, China
4 School of Physics, Peking University, Beijing 100871, China
5 School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
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.
Matter and Radiation at Extremes
2021, 6(6): 064401
1 中国工程物理研究院 激光聚变研究中心 等离子体物理重点实验室,四川 绵阳 621900
2 北京大学 核物理与核技术国家重点实验室,北京 100871
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。
激光脉冲中子源 中子产额 中子转换体 多反应通道 laser pulse neutron source neutron yield neutron converter multi reaction channels 
2021, 33(9): 094004
Author Affiliations
1 State Key Laboratory of Nuclear Physics and Technology, Center for Applied Physics and Technology, School of Physics, Peking University, Beijing100871, China
2 Beijing Laser Acceleration Innovation Center, Beijing101400, China
3 Institute of Guangdong Laser Plasma Technology, Guangzhou510540, China
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.
carbon nanotube foams laser-driven acceleration near-critical density targets ultraintense laser 
High Power Laser Science and Engineering
2021, 9(2): 02000e29
兰州交通大学 电子与信息工程学院,甘肃 兰州 730070
图像处理 线性模型 边缘信息模型 自适应透射率 image processing linear model edge information model adaptive transmittance 
2020, 41(1): 114
1 上海应用技术大学 材料科学与工程学院, 晶体生长研究所, 上海 204648
2 中核北方核燃料元件有限公司, 包头 014035
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(UOx, 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。
氧化铀 超化学计量比 晶体生长 半导体 热电 UO2 stoichiometric crystal growth semiconductor thermoelectricity 
2020, 35(11): 1183

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