利用高强度激光产生的高能质子对直接驱动内爆进行射线照相。

Using high-intensity laser-generated energetic protons to radiograph directly driven implosions.

作者信息

Zylstra A B, Li C K, Rinderknecht H G, Séguin F H, Petrasso R D, Stoeckl C, Meyerhofer D D, Nilson P, Sangster T C, Le Pape S, Mackinnon A, Patel P

机构信息

Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

出版信息

Rev Sci Instrum. 2012 Jan;83(1):013511. doi: 10.1063/1.3680110.

DOI:10.1063/1.3680110

PMID:22299955

Abstract

The recent development of petawatt-class lasers with kilojoule-picosecond pulses, such as OMEGA EP [L. Waxer et al., Opt. Photonics News 16, 30 (2005)], provides a new diagnostic capability to study inertial-confinement-fusion (ICF) and high-energy-density (HED) plasmas. Specifically, petawatt OMEGA EP pulses have been used to backlight OMEGA implosions with energetic proton beams generated through the target normal sheath acceleration (TNSA) mechanism. This allows time-resolved studies of the mass distribution and electromagnetic field structures in ICF and HED plasmas. This principle has been previously demonstrated using Vulcan to backlight six-beam implosions [A. J. Mackinnon et al., Phys. Rev. Lett. 97, 045001 (2006)]. The TNSA proton backlighter offers better spatial and temporal resolution but poorer spatial uniformity and energy resolution than previous D(3)He fusion-based techniques [C. Li et al., Rev. Sci. Instrum. 77, 10E725 (2006)]. A target and the experimental design technique to mitigate potential problems in using TNSA backlighting to study full-energy implosions is discussed. The first proton radiographs of 60-beam spherical OMEGA implosions using the techniques discussed in this paper are presented. Sample radiographs and suggestions for troubleshooting failed radiography shots using TNSA backlighting are given, and future applications of this technique at OMEGA and the NIF are discussed.

摘要

最近皮瓦级激光器的发展，如拥有千焦级皮秒脉冲的OMEGA EP激光器[L. Waxer等人，《光学与光子学新闻》16，30（2005）]，为研究惯性约束聚变（ICF）和高能量密度（HED）等离子体提供了一种新的诊断能力。具体而言，皮瓦级的OMEGA EP脉冲已被用于通过靶面法线鞘层加速（TNSA）机制产生的高能质子束对OMEGA内爆进行背光照明。这使得能够对ICF和HED等离子体中的质量分布和电磁场结构进行时间分辨研究。此前已利用Vulcan对六束内爆进行背光照明证明了这一原理[A. J. Mackinnon等人，《物理评论快报》97，045001（2006）]。与之前基于D(3)He聚变的技术相比，TNSA质子背光照明具有更好的空间和时间分辨率，但空间均匀性和能量分辨率较差[C. Li等人，《科学仪器评论》77，10E725（2006）]。本文讨论了一种用于减轻在使用TNSA背光照明研究全能量内爆时潜在问题的靶材和实验设计技术。展示了使用本文所讨论技术对60束球形OMEGA内爆进行的首批质子射线照相。给出了示例射线照片以及对使用TNSA背光照明的失败射线照相拍摄进行故障排除的建议，并讨论了该技术在OMEGA和国家点火装置（NIF）上的未来应用。