混合驱动下高熵高内爆速度中心点火靶设计

doi:10.19596/j.cnki.1001-246x.8626

摘要/Abstract

摘要：

报道混驱点火靶设计的最新进展，给出高熵(> 3.0)高内爆速度(> 400 km·s^-1)的中心点火靶设计。首先利用两台阶的间驱辐射波形(峰值温度为200 eV)烧蚀和预压缩靶丸；然后用功率为340 TW的直驱光和间驱共同作用驱动靶丸内爆。混驱下的“推土机”效应把辐射烧蚀的冕区等离子体堆积成高密度平台，产生高达500 Mbar以上的驱动压力，实现了高熵(约为3.4)高内爆速度(约为425 km·s^-1)下的中心点火靶设计，对应热斑压力在200 Gbar左右，收缩比只有23倍。二维模拟热斑界面处中线性增长因子 < 10，表明该靶设计更容易形成健壮的点火热斑。

关键词: 混合驱动, 高内爆速度, 高熵, 线性增长因子, 健壮点火热斑

Abstract:

We report new progress in hybrid-drive (HD) ignition target design with a high-adiabat (>3.0) and high-velocity (>400 km·s^-1). First, two-shock indirect-drive (ID) radiation temperature with lower peak 200 eV ablates and pre-compresses the capsule. Later, direct-drive lasers of power 340 TW in flat-top pulse are absorbed near critical surface, combined with the radiation to drive the implosions. The "snowplow" effect in the HD heaps low ID corona density into a high HD plasma density at the radiation ablation front where maximal HD pressure reaches over 500 Mbar. Such high pressure further drives capsule imploding with peak velocity about 424.5 km·s^-1 and fuel aidabat about 3.4, and the high-velocity and high-adiabat lower the hotspot pressure required to ignition lower to about 200 Gbar at a low convergent ratio 23 to suppress hydrodynamic instabilities. 2D simulation also predicts the growth factor (GF) at hotspot is very small < 10, beneficial for a robust hotspot and further burn.

Key words: hybrid-drive, high implosion velocity, high adiabat, growth factor, robust hot spot

李纪伟, 王立锋, 李志远, 陈耀桦, 许琰, 何民卿, 李斌, 吴俊峰, 叶文华, 贺贤土. 混合驱动下高熵高内爆速度中心点火靶设计[J]. 计算物理, 2023, 40(2): 181-188.

Jiwei LI, Lifeng WANG, Zhiyuan LI, Yaohua CHEN, Yan XU, Minqing HE, Bin LI, Junfeng WU, Wenhua YE, Xiantu HE. A High-adiabat and High-velocity Capsule Imploded by High Hybrid-drive Pressure for Inertial Confinement Fusion[J]. Chinese Journal of Computational Physics, 2023, 40(2): 181-188.

图/表 9

图1 不同热斑内能下中心点火要求的热斑压力

Fig.1 Ignition required hotspot pressure for different internal energy of hotspot

图2 混驱高熵高内爆速度靶设计, 其中(a)对应球靶丸，(b)对应驱动辐射温度(含M带)和激光波形

Fig.2 Schematic of the high-velocity and high-adiabat hybrid-drive ignition target where (a) is the capsule, (b) is the indirect-drive radiation temperature including the M-band and direct-drive laser power

图3 一维模拟的冲击波、界面及飞行壳层的内爆动力学过程

Fig.3 Implosion dynamics of the shock, interface and the inflight shell in hybrid-drive by one-dimensional simulation

图4 混驱平台压力随时间变化

Fig.4 Pressure of the hybrid-driven plateau between the CWF and RAF

图5 峰值辐射温度变化对(a)熵增及驱动源结束时刻(b)壳层密度影响

Fig.5 Effect of the radiation temperature on (a) the averaged adiabat of fuel and (b) density of the shell at end of the drive source

表1 间驱辐射温度峰值对混驱点火靶性能影响

Table 1 Effect of the peak radiation temperature on the hybrid-driven ignition

峰值辐射温度/eV	放能/MJ	内爆速度/(km·s^-1)	熵增	燃料面密度/(g·cm^-2)
200	17.12	425	3.43	1.06
180	12.87	420.7	3.756	1.0
170	9.375	419.1	4.11	0.964
160	1.07	408.9	4.863	0.775

表2 直驱光功率对混驱点火靶性能影响

Table 2 Effect of the direct-drive laser power on the hybrid-driven igntion

直驱光功率/TW	放能/MJ	内爆速度/(km·s^-1)	熵增	燃料面密度/(g·cm^-2)
340	17.12	425	3.43	1.06
320	16.5	421.2	3.46	1.055
300	13.5	410.1	3.65	1.02

图6 不同点火模型(a)烧蚀面处和(b)热斑界面处的线性增长因子对比

Fig.6 Comparisons of the linear growth factor (GF) at (a) the ablation front and (b) hotspot interface for the HD and ID CH high-foot design

图7 直驱光强度不均匀性对混驱点火靶放能影响

Fig.7 Degradation of Y2D/Y1D by the laser intensity nonuniformity

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[2]	谷建法, 戴振生, 叶文华, 古培俊, 郑无敌. 点火靶高熵内爆的数值模拟[J]. 计算物理, 2015, 32(6): 662-668.