Self-generated Terahertz Radiation and Relativistic Optics: A Novel Diagnostic for Table top Laser Particle Accelerators

该项目的重点是目标正常鞘加速（TNSA）场的时空特性，这是负责在相对论激光固体相互作用过程中的离子和质子的加速。理论研究已经预测，这些领域是TV/m的顺序，本地化的空间尺寸可比的激光波长，并可能持续几倍的激光脉冲持续时间。这些领域的极端时空特性，使他们很难被外部probes.In该项目中，我们提出了一种新的，非侵入性的诊断这些领域的准确测量。这个原理很简单，但却可以对这些极端场进行真正有力的表征。由于TNSA场的瞬态性质，在靶的后部的电子-离子鞘应充当振荡偶极子。带电粒子的这种加速运动在THz频域中感应电磁辐射。最初的实验是在IOQ（光学和量子电子学研究所）的JETI（Jena TI-Sapphire系统）激光设施中与Jena的IPHT（光子技术研究所）合作进行的。基于这些实验的可喜成果，我们的目标是系统地调查TNSA通过先进的太赫兹诊断和计算机模拟研究，使用等离子体模拟代码。最终目标是将发射的THz辐射的特征与TNSA场的动力学相关联，从而开发出一种独特的诊断工具，该工具可用于优化激光离子加速。

The project focuses on the spatio-temporal characterization of the Target Normal Sheath Acceleration (TNSA) field which is responsible for the acceleration of ions and protons during relativistic laser-solid interaction. Theoretical studies have predicted that these fields are of the order of TV/m, localized in a spatial dimension comparable to the laser wavelength and may last several times the laser pulse duration. The extreme spatio-temporal characteristics of these fields make them difficult to be accessed by external probes.In this project we propose a novel, non-invasive diagnostic for the accurate measurement of these fields. The principle is simple but allows a truly powerful characterization of these extreme fields. Due to the transient nature of the TNSA field, the electron-ion sheath at the rear of the target should act as an oscillating dipole. This accelerated motion of charged particles induces electromagnetic radiation in the THz frequency domain. Initial experiments were carried out at the JETI (JEna TI-Sapphire system) laser facility at the IOQ (Institute for Optics and Quantum electronics in cooperation with the IPHT (Institute of Photonic Technology) Jena. Based on the promising results from these experiments we aim at investigating systematically the TNSA by means of both advanced THz diagnostics and computer simulation studies using Plasma Simulation Code. The ultimate goal is to relate the features of the emitted THz radiation to the dynamics of the TNSA field, and thus developing a unique diagnostic tool which can be employed to optimise the ion acceleration with lasers.