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2017
Volume: 2 Issue 1
6 Article(s)
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Editorial for special issue on laser fusion
Ke Lan
It is a dream of worldwide scientists to demonstrate fusion ignition and gain in the laboratory. The demonstration of laboratory fusion ignition via Inertial Confinement Fusion (ICF) will allow scientists to understand processes in the cores of stars, to point the way toward carbon-free energy with virtually unlimited It is a dream of worldwide scientists to demonstrate fusion ignition and gain in the laboratory. The demonstration of laboratory fusion ignition via Inertial Confinement Fusion (ICF) will allow scientists to understand processes in the cores of stars, to point the way toward carbon-free energy with virtually unlimited fuel supply, and to contribute to maintaining a safe and reliable nuclear deterrent without testing. In addition, the facilities, diagnostics and modeling developed for fusion research have enabled the emerging field of high energy density physics (HEDP) that impacts a broad range of topics including condensed matter, planetary and stellar science..
Matter and Radiation at Extremes
- Publication Date: Jan. 17, 2018
- Vol. 2, Issue 1, 1 (2017)
Letter
Non-equilibrium between ions and electrons inside hot spots from National Ignition Facility experiments
Zhengfeng Fan, Yuanyuan Liu, Bin Liu, Chengxin Yu... and Jie Liu|Show fewer author(s)
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 enlargeThe 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. 17, 2018
- Vol. 2, Issue 1, 3 (2017)
Research Article
Effects of mode coupling between low-mode radiation flux asymmetry and intermediate-mode ablator roughness on ignition capsule implosions
Jianfa Gu, Zhensheng Dai, Shiyang Zou, Wenhua Ye... and Shaoping Zhu|Show fewer author(s)
The low-mode shell asymmetry and high-mode hot spot mixing appear to be the main reasons for the performance degradation of the National Ignition Facility (NIF) implosion experiments. The effects of the mode coupling between low-mode P2 radiation flux asymmetry and intermediate-mode L= 24 capsule roughness on the imploThe low-mode shell asymmetry and high-mode hot spot mixing appear to be the main reasons for the performance degradation of the National Ignition Facility (NIF) implosion experiments. The effects of the mode coupling between low-mode P2 radiation flux asymmetry and intermediate-mode L= 24 capsule roughness on the implosion performance of ignition capsule are investigated by two-dimensional radiation hydrodynamic simulations. It is shown that the amplitudes of new modes generated by the mode coupling are in good agreement with the second-order mode coupling equation during the acceleration phase. The later flow field not only shows large areal density P2 asymmetry in the main fuel, but also generates large-amplitude spikes and bubbles. In the deceleration phase, the increasing mode coupling generates more new modes, and the perturbation spectrum on the hot spot boundary is mainly from the strong mode interactions rather than the initial perturbation conditions. The combination of the low-mode and high-mode perturbations breaks up the capsule shell, resulting in a significant reduction of the hot spot temperature and implosion performance..
Matter and Radiation at Extremes
- Publication Date: Jan. 17, 2018
- Vol. 2, Issue 1, 9 (2017)
Aluminum X-ray mass-ablation rate measurements
J.L. Kline, and J.D. Hager
Measurements of the mass ablation rate of aluminum (Al) have been completed at the Omega Laser Facility. These measurements show that the mass-ablation rate of Al is higher than plastic (CH), comparable to high density carbon (HDC), and lower than beryllium. The mass-ablation rate is consistent with predictions using aMeasurements of the mass ablation rate of aluminum (Al) have been completed at the Omega Laser Facility. These measurements show that the mass-ablation rate of Al is higher than plastic (CH), comparable to high density carbon (HDC), and lower than beryllium. The mass-ablation rate is consistent with predictions using a 1D Lagrangian code, Helios. The results suggest Al capsules have a reasonable ablation pressure even with a higher albedo than beryllium or carbon ablators and further investigation into the viability of Al capsules for ignition should be pursued..
Matter and Radiation at Extremes
- Publication Date: Jan. 17, 2018
- Vol. 2, Issue 1, 16 (2017)
Analysis of hohlraum energetics of the SG series and the NIF experiments with energy balance model
Guoli Ren, Jie Liu, Wenyi Huo, and Ke Lan
The basic energy balance model is applied to analyze the hohlraum energetics data from the Shenguang (SG) series laser facilities and the National Ignition Facility (NIF) experiments published in the past few years. The analysis shows that the overall hohlraum energetics data are in agreement with the energy balance moThe basic energy balance model is applied to analyze the hohlraum energetics data from the Shenguang (SG) series laser facilities and the National Ignition Facility (NIF) experiments published in the past few years. The analysis shows that the overall hohlraum energetics data are in agreement with the energy balance model within 20% deviation. The 20% deviation might be caused by the diversity in hohlraum parameters, such as material, laser pulse, gas filling density, etc. In addition, the NIF's ignition target designs and our ignition target designs given by simulations are also in accordance with the energy balance model. This work confirms the value of the energy balance model for ignition target design and experimental data assessment, and demonstrates that the NIF energy is enough to achieve ignition if a 1D spherical radiation drive could be created, meanwhile both the laser plasma instabilities and hydrodynamic instabilities could be suppressed..
Matter and Radiation at Extremes
- Publication Date: Jan. 17, 2018
- Vol. 2, Issue 1, 22 (2017)
On intense proton beam generation and transport in hollow cones
J.J. Honrubia, A. Morace, and M. Murakami
Proton generation, transport and interaction with hollow cone targets are investigated by means of two-dimensional PIC simulations. A scaled-down hollow cone with gold walls, a carbon tip and a curved hydrogen foil inside the cone has been considered. Proton acceleration is driven by a 1020 W?cm2 and 1 ps laser pulse fProton generation, transport and interaction with hollow cone targets are investigated by means of two-dimensional PIC simulations. A scaled-down hollow cone with gold walls, a carbon tip and a curved hydrogen foil inside the cone has been considered. Proton acceleration is driven by a 1020 W?cm2 and 1 ps laser pulse focused on the hydrogen foil. Simulations show an important surface current at the cone walls which generates a magnetic field. This magnetic field is dragged by the quasi-neutral plasma formed by fast protons and co-moving electrons when they propagate towards the cone tip. As a result, a tens of kT Bz field is set up at the cone tip, which is strong enough to deflect the protons and increase the beam divergence substantially. We propose using heavy materials at the cone tip and increasing the laser intensity in order to mitigate magnetic field generation and proton beam divergence..
Matter and Radiation at Extremes
- Publication Date: Jan. 17, 2018
- Vol. 2, Issue 1, 28 (2017)
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