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Title: A simple method to prevent hard X-ray-induced preheating effects inside the cone tip in indirect-drive fast ignition implosions

Abstract

During fast-ignition implosions, preheating of inside the cone tip caused by hard X-rays can strongly affect the generation and transport of hot electrons in the cone. Although indirect-drive implosions have a higher implosion symmetry, they cause stronger preheating effects than direct-drive implosions. To control the preheating of the cone tip, we propose the use of indirect-drive fast-ignition targets with thicker tips. Experiments carried out at the ShenGuang-III prototype laser facility confirmed that thicker tips are effective for controlling preheating. Moreover, these results were consistent with those of 1D radiation hydrodynamic simulations.

Authors:
; ; ; ; ; ; ; ; ; ; ; ;  [1];  [2]; ; ; ; ; ; more »;  [3]; « less
  1. Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang 621900 (China)
  2. (China)
  3. Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)
Publication Date:
OSTI Identifier:
22600125
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPUTERIZED SIMULATION; CONES; CONTROL; ELECTRONS; HARD X RADIATION; HEAT TREATMENTS; HYDRODYNAMIC MODEL; IMPLOSIONS; LASERS; ONE-DIMENSIONAL CALCULATIONS; SYMMETRY; THERMONUCLEAR IGNITION; TRANSPORT THEORY

Citation Formats

Liu, Dongxiao, Shan, Lianqiang, Zhou, Weimin, Wu, Yuchi, Zhu, Bin, Zhang, Feng, Bi, Bi, Zhang, Bo, Zhang, Zhimeng, Shui, Min, He, Yingling, Gu, Yuqiu, E-mail: yqgu@caep.cn, Zhang, Baohan, Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Peng, Xiaoshi, Xu, Tao, Wang, Feng, Yang, Zhiwen, Chen, Tao, Chen, Li, Chen, Ming, and and others. A simple method to prevent hard X-ray-induced preheating effects inside the cone tip in indirect-drive fast ignition implosions. United States: N. p., 2016. Web. doi:10.1063/1.4952631.
Liu, Dongxiao, Shan, Lianqiang, Zhou, Weimin, Wu, Yuchi, Zhu, Bin, Zhang, Feng, Bi, Bi, Zhang, Bo, Zhang, Zhimeng, Shui, Min, He, Yingling, Gu, Yuqiu, E-mail: yqgu@caep.cn, Zhang, Baohan, Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Peng, Xiaoshi, Xu, Tao, Wang, Feng, Yang, Zhiwen, Chen, Tao, Chen, Li, Chen, Ming, & and others. A simple method to prevent hard X-ray-induced preheating effects inside the cone tip in indirect-drive fast ignition implosions. United States. doi:10.1063/1.4952631.
Liu, Dongxiao, Shan, Lianqiang, Zhou, Weimin, Wu, Yuchi, Zhu, Bin, Zhang, Feng, Bi, Bi, Zhang, Bo, Zhang, Zhimeng, Shui, Min, He, Yingling, Gu, Yuqiu, E-mail: yqgu@caep.cn, Zhang, Baohan, Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Peng, Xiaoshi, Xu, Tao, Wang, Feng, Yang, Zhiwen, Chen, Tao, Chen, Li, Chen, Ming, and and others. Wed . "A simple method to prevent hard X-ray-induced preheating effects inside the cone tip in indirect-drive fast ignition implosions". United States. doi:10.1063/1.4952631.
@article{osti_22600125,
title = {A simple method to prevent hard X-ray-induced preheating effects inside the cone tip in indirect-drive fast ignition implosions},
author = {Liu, Dongxiao and Shan, Lianqiang and Zhou, Weimin and Wu, Yuchi and Zhu, Bin and Zhang, Feng and Bi, Bi and Zhang, Bo and Zhang, Zhimeng and Shui, Min and He, Yingling and Gu, Yuqiu, E-mail: yqgu@caep.cn and Zhang, Baohan and Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 and Peng, Xiaoshi and Xu, Tao and Wang, Feng and Yang, Zhiwen and Chen, Tao and Chen, Li and Chen, Ming and and others},
abstractNote = {During fast-ignition implosions, preheating of inside the cone tip caused by hard X-rays can strongly affect the generation and transport of hot electrons in the cone. Although indirect-drive implosions have a higher implosion symmetry, they cause stronger preheating effects than direct-drive implosions. To control the preheating of the cone tip, we propose the use of indirect-drive fast-ignition targets with thicker tips. Experiments carried out at the ShenGuang-III prototype laser facility confirmed that thicker tips are effective for controlling preheating. Moreover, these results were consistent with those of 1D radiation hydrodynamic simulations.},
doi = {10.1063/1.4952631},
journal = {Physics of Plasmas},
number = 6,
volume = 23,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}
  • Hydrodynamic instabilities can cause capsule defects and other perturbations to grow and degrade implosion performance in ignition experiments at the National Ignition Facility (NIF). Here, we show the first experimental demonstration that a strong unsupported first shock in indirect drive implosions at the NIF reduces ablation front instability growth leading to a 3 to 10 times higher yield with fuel ρR > 1 g=cm 2. This work shows the importance of ablation front instability growth during the National Ignition Campaign and may provide a path to improved performance at the high compression necessary for ignition.
  • Hydrodynamic instabilities can cause capsule defects and other perturbations to grow and degrade implosion performance in ignition experiments at the National Ignition Facility (NIF). Here, we show the first experimental demonstration that a strong unsupported first shock in indirect drive implosions at the NIF reduces ablation front instability growth leading to a 3 to 10 times higher yield with fuel ρR>1 g/cm 2. As a result, this work shows the importance of ablation front instability growth during the National Ignition Campaign and may provide a path to improved performance at the high compression necessary for ignition.
  • We demonstrate indirect-drive implosion symmetry tuning in a vacuum hohlraum 6.6 mm in length and 3.56 mm in diameter with a CH capsule 6.38 {mu}m in thickness and 1414 {mu}m in diameter, scaled roughly 0.7 x from a National ignition facility (NIF) [E. Moses and C. R. Wuest, Fusion Sci. Technol. 47, 314 (2005)] The hohlraums have radiation drives of 117 {+-} 4 eV relevant to conditions for the first {approx}1 ns of ignition experiments. By varying the relative ratio of the energy between inner and outer beam cones illuminating the hohlraum at OMEGA [T. R. Boehly et al., Opt.more » Commun. 133, 495 (1997)]. the shape of the x-ray self-emission, and hence the shape of the emitting object, can be tuned from prolate to oblate. The second-order Legendre coefficient, used to characterize the shape, changes from a negative to a positive value at the time of peak x-ray emission during the implosion through the variation of the cone power balance. With the appropriate selection of the cone power balance, the implosion can be tuned to produce a spherical implosion. Using capsules with thicker walls, this technique can be extended to measure the drive symmetry at later times as the length of the drive pulse is increased [N. M. Hoffman et al., J. Phys.: Conf. Ser. 112, 022075 (2008); N. M. Hoffman et al., Phys. Plasmas 3, 2022 (1996)].« less
  • We have performed a series of 1-D numerical simulations of the x-ray emission from National Ignition Facility (NIF) targets. Results are presented in terms of total x-ray energy, pulse length, and spectrum. Scaling of x-ray emissions is presented for variations in both target yield and hohlraum wall thickness. Experiments conducted on the Nova facility provide some validation of the computational tools and methods. 6 refs., 6 figs., 2 tabs.