强激光与粒子束
2024, 36(4): 043025
Author Affiliations
Abstract
1 Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang, China
2 Center for Applied Physics and Technology, Peking University, Beijing, China
3 Institute of Applied Physics and Computational Mathematics, Beijing, China
Competition among the two-plasmon decay (TPD) of backscattered light of stimulated Raman scattering (SRS), filamentation of the electron-plasma wave (EPW) and forward side SRS is investigated by two-dimensional particle-in-cell simulations. Our previous work [K. Q. Pan et al., Nucl. Fusion 58, 096035 (2018)] showed that in a plasma with the density near 1/10 of the critical density, the backscattered light would excite the TPD, which results in suppression of the backward SRS. However, this work further shows that when the laser intensity is so high ( $>{10}^{16}$ W/cm2) that the backward SRS cannot be totally suppressed, filamentation of the EPW and forward side SRS will be excited. Then the TPD of the backscattered light only occurs in the early stage and is suppressed in the latter stage. Electron distribution functions further show that trapped-particle-modulation instability should be responsible for filamentation of the EPW. This research can promote the understanding of hot-electron generation and SRS saturation in inertial confinement fusion experiments.
laser plasma instability inertial confinement fusion high energy density physics particle-in-cell simulation super-hot electrons High Power Laser Science and Engineering
2023, 11(6): 06000e76
Author Affiliations
Abstract
1 State Key Laboratory for GeoMechanics and Deep Underground Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
2 School of Science, China University of Mining and Technology (Beijing), Beijing 100089, China
3 Institute Key Laboratory of Optic Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
4 Songshan Lake Materials Laboratory, Dongguan 523808, China
In the scheme of fast ignition of inertial confinement fusion, the fuel temperature mainly relies on fast electrons, which act as an energy carrier, transferring the laser energy to the fuel. Both conversion efficiency from the laser to the fast electron and the energy spectrum of the fast electron are essentially important to achieve highly effective heating. In this study, a two-dimensional particle in cell simulation is applied to study the generation of fast electrons from solid-density plasmas with different laser waveforms. The results have shown that the slope of the rising edge has a significant effect on fast electron generation and energy absorption. For the negative skew pulse with a relatively slow rising edge, the mechanism can most effectively accelerate the electrons. The overall absorption efficiency of the laser energy is optimized, and the fast electron yield in the middle- and low-energy range is also improved.
laser waveform fast electrons particle-in-cell simulations plasmas Chinese Optics Letters
2023, 21(6): 063801
1 西安空间无线电技术研究所 空间微波技术重点实验室,西安 710100
2 郑州大学 物理学院,郑州 450001
3 南方科技大学 深圳市电磁信息重点实验室,广东 深圳 518055
微放电是制约航天器微波部件功率容量的主要瓶颈之一。以介质微波部件中典型的介质加载平行板波导为例,基于三维粒子模拟分别对仅考虑外加微波场(情况1)、考虑外加微波场和空间电荷(情况2)以及考虑外加微波场、空间电荷和介质表面电荷(情况3)三种情况下微放电演化过程中电子数目、瞬态二次电子发射系数、归一化反射波电压以及介质表面与上金属板之间的间隙电压随时间的变化进行了仿真,并给出了情况3电子分布和介质表面电荷密度随时间的变化过程。在此基础上,明确了空间电荷和介质表面电荷在微放电过程中所起的不同作用:即空间电荷会使微放电达到饱和状态,介质表面电荷则导致微放电饱和状态无法持续,最后自行熄灭。介质表面电荷导致了微放电过程中介质和金属瞬态二次电子发射系数下降速率不一致,归一化反射波电压幅度随时间变化的包络类似于“眼睛”形状、间隙电压类直流偏置、非对称电子能量分布等特殊现象。
微放电 空间电荷 介质表面电荷 粒子模拟 multipactor space charge surface charge on the dielectric particle-in-cell simulation 强激光与粒子束
2023, 35(3): 033003
红外与毫米波学报
2022, 41(6): 1042
强激光与粒子束
2022, 34(4): 049002
中国原子能科学研究院核物理研究所,北京 102413
为了增强相对论飞秒激光与固体靶相互作用下太赫兹波的产生,提出了前端锥形开口的纳米丝靶结构,并通过胞中粒子法(Particle-In-Cell)数值模拟,研究了该结构对太赫兹波产生的影响,还与普通结构的纳米丝靶所产生的太赫兹波结果进行了对比。结果显示,前端锥形开口的纳米丝靶结构能够明显增强太赫兹波的产生,在探测点位置得到了比普通纳米丝靶中的太赫兹波电场强3倍的结果。最后详细分析了不同靶型结构影响太赫兹波产生的物理因素,发现不同靶型结构通过影响入射激光的吸收与反射,进而影响靶后超热电子的能量与数目。上述研究结果将有助于推动强场太赫兹波领域的发展,为实验研究提供方案和数据支撑。
激光技术 太赫兹波 微结构靶 飞秒激光 胞中粒子法数值模拟 激光等离子体
强激光与粒子束
2021, 33(12): 123014
强激光与粒子束
2021, 33(9): 093006