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Optimising laser driven electron nanobunches from ultrathin foil interactions: Coherent synchrotron emission and relativistic electron mirrors

通过超薄箔相互作用优化激光驱动电子纳米束：相干同步加速器发射和相对论电子镜

基本信息

批准号：
EP/L02327X/1
负责人：
Brendan Hugh Dromey
金额：
$ 89.18万
依托单位：
Queen's University Belfast
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FL02327X%2F1
关键词：
Optimising laser driven electron nanobunches

项目摘要

Summary of research for a general audience One of the most exciting frontiers of science is the study of phenomena that take place on the timescale of attoseconds (as, 10^-18 s). To imagine such an incredibly short period of time, consider that light travels from here to the moon in one second, but only travels 0.0003mm in one femtosecond (fs, 10^-15 s). To put it in context, that is about 1/300th the width of a human hair in 10^-15 s (or 1000 as). Attoseconds are the timescales on which atomic processes/transitions occur - for example, an electron circles the hydrogen atom in ~24 as (the so called 'atomic unit of time'). To investigate, and in future control, the dynamics of such ultrafast processes measurement tools of unprecedented quality and precision are required - pulses of light with attosecond duration. This is much shorter than a single cycle of any visible light wave (violet~1.3fs, red~2.5fs), requiring instead extreme-ultraviolet (XUV)/ X-ray radiation to be controlled with clinical accuracy to achieve ultrashort durations. However, the pay-off for this effort is substantial; researchers can investigate the microcosm with a degree of spatial clarity and on shorter time scales than previously possible, thus allowing them to see events that are ordinarily 'blurred' using conventional XUV/X-ray sources such as synchrotrons.Attosecond pulses must be synthesized using wavelengths shorter than those in the visible region of the spectrum and therein lies a significant problem - wavelengths shorter than the visible spectrum i.e. ultraviolet and X-rays, are strongly absorbed in most materials. It is therefore impossible to build an attosecond laser using conventional laser building techniques. Instead next generation methods are required. Two principle media are currently being studied at laser laboratories around the world - intense laser-gas interactions and relativistic laser plasmas formed using solid density targets - for the production of attosecond pulses.In the proposed research we focus on the second medium - relativistic laser plasma. The underlying mechanism under investigation for the generation of intense attosecond pulses is the production of relativistic electron nanobunches during high power optical laser interactions with ultrathin carbon foils. This novel concept is based on our recent work showing that dense bunches of electrons with sub 10nm scale (nm = nanometer = 10^-9m) can be formed and rapidly accelerated on the front surface by the relativistically intense driving laser field and subsequently emerge from the rear surface of ultrathin carbon foils. Two resulting mechanisms will be studied in detail in this research - Coherent Synchrotron Emission (CSE) and Relativistic Electron Mirrors (REM). Only recently demonstrated, CSE and REM offer a novel window onto the relativistic laser plasma interaction and our work will not only reveal the microscopic dynamics of these mechanisms but also show a direct path to the generation of bright attosecond pulses.

科学最令人兴奋的前沿领域之一是对发生在阿秒（as，10^-18 s）时间尺度上的现象的研究。为了想象这样一个难以置信的短时间段，考虑光从这里到月球在一秒内传播，但在一飞秒（fs，10^-15 s）内仅传播0.0003 mm。在上下文中，这大约是10^-15 s（或1000 as）内人类头发宽度的1/300。阿秒是原子过程/跃迁发生的时间尺度-例如，一个电子在~24 as（所谓的“原子时间单位”）内绕氢原子一周。为了调查，并在未来的控制，这种超快过程的动态测量工具的前所未有的质量和精度是必需的-阿秒持续时间的光脉冲。这比任何可见光波（紫色~1.3fs，红色~2.5fs）的单个周期短得多，需要以临床精度控制极紫外（XUV）/X射线辐射以实现超短持续时间。然而，这一努力的回报是巨大的;研究人员可以在比以前可能的更短的时间尺度上以一定程度的空间清晰度来研究微观世界，因此使他们能够看到通常使用常规XUV/X射线源（如同步加速器）“模糊”的事件。阿秒脉冲必须使用比光谱的可见光区域中的波长短的波长来合成，这存在一个显著的问题-短于可见光谱的波长，即紫外线和X射线，在大多数材料中被强烈吸收。因此，不可能使用传统的激光器构建技术来构建阿秒激光器。需要下一代的方法。目前世界各地的激光实验室正在研究产生阿秒脉冲的两种主要介质--强激光-气体相互作用和使用固体密度靶形成的相对论激光等离子体。强阿秒脉冲产生的潜在机制是在高功率光激光与碳箔相互作用过程中产生相对论电子纳米束。这一新概念是基于我们最近的工作，即在相对论强驱动激光场作用下，可以在碳箔的前表面形成亚10 nm尺度（nm = nanometer = 10^-9 m）的密集电子束团，并使其快速加速，随后从碳箔的后表面射出。本研究将详细研究两种产生机制-相干同步辐射（CSE）和相对论电子镜（REM）。最近才证实，CSE和REM提供了一个新的窗口相对论激光等离子体相互作用，我们的工作不仅揭示了这些机制的微观动力学，但也显示了一个直接的路径产生明亮的阿秒脉冲。