Letter|3 Article(s)
Non-equilibrium between ions and electrons inside hot spots from National Ignition Facility experiments
Zhengfeng Fan, Yuanyuan Liu, Bin Liu, Chengxin Yu, Ke Lan, and Jie Liu
The non-equilibrium between ions and electrons in the hot spot can relax the ignition conditions in inertial confinement fusion [Fan et al., Phys. Plasmas 23, 010703 (2016)], and obvious ion-electron non-equilibrium could be observed by our simulations of high-foot implosions when the ion-electron relaxation is enlarged by a factor of 2. On the other hand, in many shots of high-foot implosions on the National Ignition Facility, the observed X-ray enhancement factors due to ablator mixing into the hot spot are less than unity assuming electrons and ions have the same temperature [Meezan et al., Phys. Plasmas 22, 062703 (2015)], which is not self-consistent because it can lead to negative ablator mixing into the hot spot. Actually, this non-consistency implies ion-electron non-equilibrium within the hot spot. From our study, we can infer that ionelectron non-equilibrium exists in high-foot implosions and the ion temperature could be ~9% larger than the equilibrium temperature in some NIF shots. The non-equilibrium between ions and electrons in the hot spot can relax the ignition conditions in inertial confinement fusion [Fan et al., Phys. Plasmas 23, 010703 (2016)], and obvious ion-electron non-equilibrium could be observed by our simulations of high-foot implosions when the ion-electron relaxation is enlarged by a factor of 2. On the other hand, in many shots of high-foot implosions on the National Ignition Facility, the observed X-ray enhancement factors due to ablator mixing into the hot spot are less than unity assuming electrons and ions have the same temperature [Meezan et al., Phys. Plasmas 22, 062703 (2015)], which is not self-consistent because it can lead to negative ablator mixing into the hot spot. Actually, this non-consistency implies ion-electron non-equilibrium within the hot spot. From our study, we can infer that ionelectron non-equilibrium exists in high-foot implosions and the ion temperature could be ~9% larger than the equilibrium temperature in some NIF shots.
Matter and Radiation at Extremes
- Publication Date: Jan. 01, 2017
- Vol. 2, Issue 1, 3 (2017)
Proton radiography of magnetic fields generated with an open-ended coil driven by high power laser pulses
Guoqian Liao, Yutong Li, Baojun Zhu, Yanfei Li, Fang Li, Mengchao Li, Xuan Wang, Zhe Zhang, Shukai He, Weiwu Wang, Feng Lu, Faqiang Zhang, Lei Yang, Kainan Zhou, Na Xie, Wei Hong, Yuqiu Gu, Zongqing Zhao, Baohan Zhang, and Jie Zhan
Recently generation of strong magnetic (B) fields has been demonstrated in capacitor coils heated by high power laser pulses [S. Fujioka et al., Sci. Rep. 3, 1170 (2013)]. This paper will present a direct measurement of B field generated with an open-ended coil target driven by a nanosecond laser pulse using ultrafast proton radiography. The radiographs are analyzed with particle-tracing simulations. The B field at the coil center is inferred to be ~50 T at an irradiance of -5×1014 W?cm2. The B field generation is attributed to the background cold electron flow pointing to the laser focal spot, where a target potential is induced due to the escape of energetic electrons. Recently generation of strong magnetic (B) fields has been demonstrated in capacitor coils heated by high power laser pulses [S. Fujioka et al., Sci. Rep. 3, 1170 (2013)]. This paper will present a direct measurement of B field generated with an open-ended coil target driven by a nanosecond laser pulse using ultrafast proton radiography. The radiographs are analyzed with particle-tracing simulations. The B field at the coil center is inferred to be ~50 T at an irradiance of -5×1014 W?cm2. The B field generation is attributed to the background cold electron flow pointing to the laser focal spot, where a target potential is induced due to the escape of energetic electrons.
Matter and Radiation at Extremes
- Publication Date: Jan. 01, 2016
- Vol. 1, Issue 4, 187 (2016)
First demonstration of improving laser propagation inside the spherical hohlraums by using the cylindrical laser entrance hole
Wenyi Huo, Zhichao Li, Dong Yang, Ke Lan, Jie Liu, Guoli Ren, Sanwei Li, Zhiwen Yang, Liang Guo, Lifei Hou, Xuefei Xie, Yukun Li, Keli Deng, Zheng Yuan, Xiayu Zhan, Guanghui Yuan, Haijun Zhang, Baibin Jiang, Lizhen Huang, Kai Du, Runchang Zhao, Ping Li, Wei Wang, Jingqin Su, Yongkun Ding, Xiantu He, and Weiyan Zhang
The octahedral spherical hohlraums have natural superiority in maintaining high radiation symmetry during the entire capsule implosion process in indirect drive inertial confinement fusion. While, in contrast to the cylindrical hohlraums, the narrow space between the laser beams and the spherical hohlraum wall is usually commented. In this Letter, we address this crucial issue and report our experimental work conducted on the SGIII-prototype laser facility which unambiguously demonstrates that a simple design of cylindrical laser entrance hole (LEH) can dramatically improve the laser propagation inside the spherical hohlraums. In addition, the laser beam deflection in the hohlraum is observed for the first time in the experiments. Our 2-dimensional simulation results also verify qualitatively the advantages of the spherical hohlraums with cylindrical LEHs. Our results imply the prospect of adopting the cylindrical LEHs in future spherical ignition hohlraum design. The octahedral spherical hohlraums have natural superiority in maintaining high radiation symmetry during the entire capsule implosion process in indirect drive inertial confinement fusion. While, in contrast to the cylindrical hohlraums, the narrow space between the laser beams and the spherical hohlraum wall is usually commented. In this Letter, we address this crucial issue and report our experimental work conducted on the SGIII-prototype laser facility which unambiguously demonstrates that a simple design of cylindrical laser entrance hole (LEH) can dramatically improve the laser propagation inside the spherical hohlraums. In addition, the laser beam deflection in the hohlraum is observed for the first time in the experiments. Our 2-dimensional simulation results also verify qualitatively the advantages of the spherical hohlraums with cylindrical LEHs. Our results imply the prospect of adopting the cylindrical LEHs in future spherical ignition hohlraum design.
Matter and Radiation at Extremes
- Publication Date: Jan. 01, 2016
- Vol. 1, Issue 1, 2 (2016)
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