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

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.