Ion acceleration driven by ultra-short, ultra-intense pulses

该项目旨在研究在超高功率激光辐射与物质相互作用过程中发生的一个重要过程，即离子加速到非常高的能量。这一过程能够达到微米距离，而不是在大规模加速器中获得的能量，最近由于基于一种称为啁啾脉冲放大原理的新型激光系统的发展而成为可能。离子被设置在激光照射的薄片表面的超强电场通过逃逸直接从激光获得能量的高能电子来加速离子。离子的能量与用于加速它们的激光辐射的强度成比例关系，所谓的标度定律关系可以用来预测未来可达到的能量，并将实验结果与相关理论进行比较，以检验对加速机制的理解。一种名为双子座的新型激光设备将于2007年下半年开放进行实验。该装置将通过将光集中在持续时间为30飞秒(1飞秒=10^-15 S)的超短脉冲中，在半径为微米量级的光斑中实现巨大的激光能量通量(大于10^21 W/cm^2)。理论预测表明，在这种强度下，有可能将质子加速到接近癌症放射治疗等突破性应用所需的能量。该项目旨在利用双子座发展提供的独特机会，在这一新颖的超强、超短区域内研究离子加速，并了解发生机制的细节。我们还打算通过应用我们小组开发的一种技术(质子探测)来研究超强条件下激光与物质相互作用的一些未知方面。该项目的另一个重要目标是培养这一令人兴奋的研究领域的博士生，并为他/她提供继续研究生涯所需的技能，并成为未来科学装置的熟练用户。

The project aims to investigate an important process taking place during the interaction of very high power laser radiation with matter, namely the acceleration of ions to very high energies. This process, capable to reach over micormetric distances the energies that are otherwise obtained in large scale accelerators, has been made possible very recently due to the development of a new class of laser systems based on a principle called Chirped Pulse Amplification. The ions are accelerated by ultralarge electric fields set at thesurface of laser irradiated foils by escaping high energy electrons which have acquired energy directly from the laser. The energy of the ion scales with the intensity of the laser radiation used to accelerate them, and so called scaling laws relationships can be used to predict energies reachable in the future and to compare experimental results with relevant theory in order to test the understanding of the accelerating mechanisms.A novel laser facility, accessing unprecedented intensity regimes, called GEMINI will be opened up to experiments in the second half of 2007. This facility will achieve enormous fluxes of laser energies (larger than 10^21 W/cm^2) by concentrating light in ultrashort pulses, of duration 30 femtoseconds (1 fs =10^-15 s), in spots with radius of the order of a micrometer. Theoretical predictions suggest that at this intensities it will be possible to accelerate protons up to energies close to the ones required for groundbreaking applications such as cancer radiotherapy. This projects aims to exploit the unique opportunities offered by the GEMINI development to investigate ion acceleration in this novel ultraintense, ultrashort regime, and understand the details of the mechanisms taking place. We also aim to investigate some unexplored aspects of laser-matter interactions in the ultraintense regime by applying a technique (proton probing) developed by our group to diagnose the interaction of the GEMINI laser pulses with solid and gaseous targets.Another important aim of the project is to train a PhD student in this exciting area of research, and provide him/her with the skills necessary to continue a research career and become a skilled user of future scientific installations.