等离子体光纤对高功率短脉冲激光加速轻离子束的定向操控研究

It is the objective of this project to propose a new physical scheme to control the propagation direction of light ion beams accelerated by intense ultrashort laser pulses interacting with a solid-density plasma foil. Our basic physical idea is: when relativistic energetic electron beams driven by a laser pulse transport in a hollow plasma fiber, strong self-generated electromagnetic fields form at inner and outer surfaces of the fiber. The accelerated light-ion beam propagating into the fiber is then focused by the sheath electric fields at its inner surface. On the other hand, the surface magnetic field around the fiber can change the motion direction of the ion beam along the hollow plasma fiber if the corresponding magnetic field is strong enough. It is clear that the directional control of ion beams is of important application prospects in diagnostics, photography, cancer treatment, etc. Our researches will focus to: 1) new mechanisms, principles and applications of our directional control scheme of light ion beams; 2) study the transport physical mechanism of energetic electron beams propagating in hollow plasma fibers as well as the spatiotemporal evolution characteristics of self-generated surface electromagnetic fields； 3) explore their physical processes for controlling different directions of multi-beam ions, including the design of realizing the scheme.

本项目提出采用中空等离子体光纤来定向操控超短超强激光脉冲辐照靶产生轻离子束发射方向的新物理方案，其基本物理思想为：高功率短脉冲激光与靶相互作用产生的相对论强流电子束在中空等离子体光纤中输运时，在其内外表面形成很强的表面自生电场和磁场，当超短超强激光脉冲辐照靶加速的轻离子束在等体子光纤中传输时，光纤内表面的鞘电场对离子起聚焦作用，而表面磁场可改变离子运动方向，使得束沿着等离子体光纤内壁移动，这些定向操控的离子束在诊断、照相、治疗等方面具有十分重要的科学意义与应用前景。本项目重点关注等离子体光纤对轻离子束定向操控过程的新物理机理、新规律、和新应用技术；研究激光驱动的高能电子束在等离子体光纤中输运物理规律和自生电磁场时空演化特征；探索多个离子束定向操控物理过程及相关实验方案。

超强短脉冲激光辐照靶加速高能离子束具有广泛的应用前景，特别是成像及肿瘤治疗等应用除了要求紧凑离子源具有一定的能量、数额、准单能性外，束的聚焦和方向性控制也十分重要。本项目以定向操控超强短脉冲激光辐照靶加速高能离子束发射的方向性问题为主要目标，研究了等离子体光纤对离子束定向操控的新物理方案、新物理机理及规律，并为实验研究提供相关物理参数。同时，本项目也密切关注强激光等离子体中的最新国际前沿进展，在激光等离子体研究方面也获得多项科研成果。在本项目的资助下，共发表标注论文40多篇，培养毕业博士生5名，以及正培养7名博士研究生。