Intense attoscience: A new frontier in ultrafast research - Relativistic plasmas and high harmonic generation

探测超短过程使研究人员能够了解微观世界的动力学。为了研究在最快的时间尺度上发生的进程，需要对阿秒的持续时间进行探测。迄今为止，来自气体介质的相干激光驱动x射线推动了新兴的阿秒研究领域。然而，这些光源在光子能量和通量方面是有限的，可以很容易地实现。然而，随着一些激光周期太瓦/佩瓦（10^12-10^15W）系统的出现，基于相对论振荡镜（ROM）产生的相干x射线，当超强脉冲聚焦到固体目标上时，就会产生相干x射线，超快/阿托科学的新时代正在到来。与在气体中产生的相干x射线相比，从ROM中产生的相干x射线预计具有优异的性能：高效率、最短脉冲和优异的聚焦性。此外，它们非常适合开发具有高脉冲能量的激光器-导致每个脉冲的XUV光子通量比迄今为止高出许多数量级。这一提议的主要目的是相干地利用相对论等离子体介质，并演示由此产生的超强XUV脉冲的首次应用。这样的进步将使研究人员能够获得一种可以将基于大型加速器的XUV/ x射线源的高光子通量与基于激光的XUV源的阿秒持续时间相结合的源，从而开辟了全新的研究途径。

Probing ultrashort processes allows researchers to understand the dynamics of the microcosm. To investigate processes that occur on the fastest timescales, probes on the duration of attoseconds are required. Coherent laser-driven X-rays from gaseous media has fuelled the nascent field of attosecond research to date. However, these sources are limited in the photon energy and flux that can readily be achieved. With the advent of few laser cycle Terawatt/Petawatt (10^12-10^15W) systems however, a new age in ultrafast/atto-science is dawning, based on coherent X-rays generated from relativistically oscillating mirrors (ROM), which are created when an ultra-intense pulse is focused onto a solid target. The coherent X-rays that are generated from ROM have/are predicted to have excellent properties when compared with those generated in gases: high efficiency, shortest pulses and excellent focusability. In addition they are ideally suited to exploit lasers with high pulse energies - resulting in an XUV photon flux per pulse that is many orders of magnitude higher than to date. The principle aim of this proposal is to coherently harness the relativistic plasma medium and the demonstrate first applications of the resulting ultra-intense XUV pulses. Such advances will permit researchers access to a source that can combine the high photon flux available at large accelerator based XUV/X-ray sources with the attosecond duration of laser based XUV sources, opening completely new avenues of research.