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Temperature Relaxation in Dense, Reacting Plasmas

致密反应等离子体中的温度弛豫

基本信息

批准号：
EP/I014888/1
负责人：
Dirk Gericke
金额：
$ 12.41万
依托单位：
University of Warwick
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FI014888%2F1
关键词：
Temperature Relaxation Dense Reacting Plasmas

项目摘要

Understanding the properties of high energy density matter is both fundamental physics and one of the central problems that needs to be resolved before inertial confinement fusion can provide a clean and almost infinite energy source. Major steps toward this goal are being made at the moment: the National Ignition Facility in Livermore, USA has been completed last year and ignition (defined as larger energy output than input) is expected to be achieved this autumn. Ignition at NIF will have a similar impact on physics and society as the particle physics experiments using the LHC at CERN.The first experimental results support the positive predictions for full scale fusion experiments: they have demonstrated excellent energy coupling from the large scale laser systems with 192 beams into the millimeter-size cavity. Now the physics of a burning plasma has to be explored. This is done by a combination of experiments and large scale simulations. The latter are a key element of the project as the experiments are infrequent (maximum two shots a day) and very expensive. The simulations need to incorporate many physical processes; not all of them are fully understood. As a result, approximate models are currently used with represents a clear caveat for future progress.This project is aimed to substantially improve this situation for one important quantity: the electron-ion coupling. It will give definitive answers for the energy transfer rates for the whole range of parameters that occur during the heating of the fuel to fusion temperature of 10 million degrees. These energy transfer rates are needed to describe the propagation of a burn wave in the pre-compressed fuel, a process that allows for high gain targets. Interestingly, the first phase when the plasma is relatively cold is most difficult to describe as here the quantum nature of the electrons and strong forces between the ions play a major role. The quantum statistical model developed by the applicant will prove invaluable for this application.Dedicated to a specific problem within the fusion program (equation of state, melting or transport properties), a series of intermediate scale experiments has been performed over the last years. The rapid energy deposition into samples applied here creates systems with different electron and ion temperatures. Again, temperature equilibration is a major issue for the design and interpretation of the experiments. Moreover, recombination and ionisation processes are often driven by the energy deposition of the laser. The main part of this project aims to remove the theoretical uncertainties in the description of the relaxation processes involved. In particular, it will give a description of the full interplay between the changing species temperatures, the changing charge state of the ions and time-dependent correlations. In the dense matter under investigation, all of these energy contributions are of the same order of magnitude and neither can be neglected.It is very interesting to notice that intermediate scale laser experiments often reach conditions similar to those in astrophysical objects such as giant planets (including a rapidly growing number outside of our solar system), old stars and dim, midsize objects. The experimental investigation of such states, called laboratory astrophysics, requires that thermodynamic equilibrium is reached. Thus, the relaxation time is here of particular interest as it defines the minimum time delay between creation of the system and the probing. The theory developed here will provide these times.

了解高能量密度物质的性质既是基础物理学，也是惯性约束聚变能够提供清洁且几乎无限的能源之前需要解决的核心问题之一。目前正在朝着这一目标迈出重要步伐：位于美国利弗莫尔的国家点火设施已于去年完工，点火（定义为能量输出大于输入）预计将于今年秋季实现。NIF的点火将对物理学和社会产生与CERN的LHC粒子物理实验类似的影响。第一个实验结果支持了全尺寸聚变实验的积极预测：它们显示了从192束激光到毫米级腔的良好能量耦合。现在，我们必须探索燃烧等离子体的物理学。这是通过实验和大规模模拟相结合来完成的。后者是该项目的关键要素，因为实验不频繁（每天最多两次），而且非常昂贵。模拟需要结合许多物理过程;并非所有这些都被完全理解。因此，目前使用的近似模型代表了对未来进展的明确警告。该项目旨在大幅改善一个重要量的这种情况：电子-离子耦合。它将为燃料加热到1000万度聚变温度期间发生的整个参数范围的能量转移率给出明确的答案。需要这些能量传递率来描述预压缩燃料中燃烧波的传播，这是一个允许高增益目标的过程。有趣的是，当等离子体相对较冷时的第一阶段最难描述，因为在这里电子的量子性质和离子之间的强力起着主要作用。由申请人开发的量子统计模型将被证明对这一应用是无价的。致力于聚变计划中的特定问题（状态方程、熔化或输运性质），在过去几年中已经进行了一系列中等规模的实验。在这里应用的样品中的快速能量沉积产生了具有不同电子和离子温度的系统。同样，温度平衡是实验设计和解释的主要问题。此外，复合和电离过程通常由激光的能量沉积驱动。本项目的主要部分旨在消除所涉及的弛豫过程的描述中的理论不确定性。特别是，它将给出一个完整的相互作用之间的变化的物种温度，变化的离子和时间依赖的相关性的电荷状态的描述。在所研究的致密物质中，所有这些能量的贡献都是相同的数量级，而且都不能忽略。非常有趣的是，中等尺度的激光实验经常达到与天体物理学物体类似的条件，如巨行星（包括太阳系外数量迅速增加的行星）、老恒星和暗淡的中等大小的物体。对这种状态的实验研究，称为实验室天体物理学，要求达到热力学平衡。因此，弛豫时间在这里是特别感兴趣的，因为它定义了系统创建和探测之间的最小时间延迟。这里发展的理论将提供这些时间。

项目成果

期刊论文数量（8）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Observation of inhibited electron-ion coupling in strongly heated graphite.

DOI：
10.1038/srep00889
发表时间：
2012
期刊：
Scientific reports
影响因子：
4.6
作者：
White TG;Vorberger J;Brown CR;Crowley BJ;Davis P;Glenzer SH;Harris JW;Hochhaus DC;Le Pape S;Ma T;Murphy CD;Neumayer P;Pattison LK;Richardson S;Gericke DO;Gregori G
通讯作者：
Gregori G

Electron-phonon equilibration in laser-heated gold films