The nuclear burn history provides critical information about the dynamics of the hot-spot formation and high-density fuel-shell assembly of an Inertial Confinement Fusion (ICF) implosion, as well as information on the impact of alpha heating, and a multitude of implosion failure mechanisms. Having this information is critical for assessing the energy-confinement time τE and performance of an implosion. As the confinement time of an ICF implosion is a few tens of picoseconds, less than 10-ps time resolution is required for an accurate measurement of the nuclear burn history. In this study, we propose a novel 1-ps time-resolution detection scheme based on the Pockels effect. In particular, a conceptual design for the experiment on the National Ignition Facility and OMEGA are elaborated upon herein. A small organic Pockels crystal "DAST" is designed to be positioned ∼5 mm from the ICF implosion, which is scanned by a chirped pulse generated by a femto-second laser transmitted through a polarization-maintained optical fiber. The originally linearly polarized laser is changed to an elliptically polarized laser by the Pockels crystal when exposed to neutrons, and the modulation of the polarization will be analyzed. Our study using 35-MeV electrons showed that the system impulse response is 0.6 ps. The response time is orders of magnitude shorter than current systems. Through measurements of the nuclear burn history with unprecedented time resolution, this system will help for a better understanding of the dynamics of the hot-spot formation, high-density fuel-shell assembly, and the physics of thermonuclear burn wave propagation.

中文翻译：

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欧米茄和国家点火装置用于聚变反应历史测量的 1 ps 时间分辨率中子探测器的概念设计

核燃烧历史提供了关于惯性约束聚变 (ICF) 内爆的热点形成和高密度燃料壳组件动力学的关键信息，以及有关 α 加热和大量内爆影响的信息失效机制。拥有这些信息对于评估能量限制时间 τE 和内爆性能至关重要。由于 ICF 内爆的限制时间为几十皮秒，因此准确测量核燃烧历史需要不到 10 ps 的时间分辨率。在这项研究中，我们提出了一种基于 Pockels 效应的新型 1 ps 时间分辨率检测方案。特别是对国家点火装置和欧米茄实验的概念设计进行了阐述。一个小的有机 Pockels 水晶“DAST” 被设计为距离 ICF 内爆约 5 毫米，由飞秒激光产生的啁啾脉冲扫描，该脉冲通过保偏光纤传输。当暴露于中子时，由普克尔斯晶体将原来的线偏振激光变为椭圆偏振激光，并分析偏振的调制。我们使用 35-MeV 电子的研究表明，系统脉冲响应为 0.6 ps。响应时间比当前系统短几个数量级。通过以前所未有的时间分辨率测量核燃烧历史，该系统将有助于更好地了解热点形成的动力学、高密度燃料壳组件和热核燃烧波传播的物理学。它由通过保偏光纤传输的飞秒激光产生的啁啾脉冲进行扫描。当暴露于中子时，由普克尔斯晶体将原来的线偏振激光变为椭圆偏振激光，并分析偏振的调制。我们使用 35-MeV 电子的研究表明，系统脉冲响应为 0.6 ps。响应时间比当前系统短几个数量级。通过以前所未有的时间分辨率测量核燃烧历史，该系统将有助于更好地了解热点形成的动力学、高密度燃料壳组件和热核燃烧波传播的物理学。它由通过保偏光纤传输的飞秒激光产生的啁啾脉冲进行扫描。当暴露于中子时，由普克尔斯晶体将原来的线偏振激光变为椭圆偏振激光，并分析偏振的调制。我们使用 35-MeV 电子的研究表明，系统脉冲响应为 0.6 ps。响应时间比当前系统短几个数量级。通过以前所未有的时间分辨率测量核燃烧历史，该系统将有助于更好地了解热点形成的动力学、高密度燃料壳组件和热核燃烧波传播的物理学。