摘要超强激光与等离子体靶相互作用可以实现离子加速，随着激光技术的进步，目前强场激光可以提供比传统加速器高几个数量级的加速场。超强激光辐射等离子体靶时，部分激光能量转换成离子和电子的能量。目前常用的加速机制是靶后法线鞘层加速（Target Normal Sheath Acceleration，TNSA）、库仑爆炸和尾场加速等等。在此基础上，本文介绍了离子加速的背景、理论基础和应用方向，并采用的完全相对论激光辐射氩团簇靶，实验得到了高度准直且能散低的高品质氩离子束，其绝对能散为0。19MeV/核子（尖峰能量为0。39MeV/核子）。本文还利用二维PIC(Particle-In-Cell)模拟进行了探究，模拟发现氩离子束经历库仑爆炸阶段，且激光尾场对离子能量有强烈的调制作用，在一定程度上通过截掉低能量部分，从而大幅降低能谱宽度。模拟结果很好的解释了实验过程，并对实验结果进行了验证，实验和模拟均得到了低能散的高品质氩离子束。86081

毕业论文关键词  离子加速  靶后法线鞘层加速  库仑爆炸  激光尾场调制  PIC模拟

毕业设计说明书外文摘要

Title     Study on accelerating process of quasi-monoenergetic   argon ions driven by intense laser                                               

Abstract Ion acceleration can be achieved by super-intense laser interacting with plasma target。 Along with the progress of laser technology，the accelerating field at present is several orders of magnitude larger than that in conventional accelerators。 When plasma target is irradiated by intense laser,energy can be partially converted to ions。 At present, the commonly used acceleration mechanisms include the target normal sheath acceleration (TNSA), coulomb explosion, laser wakefield acceleration and so on。 On this basis, the background, theoretical basis and applications of ion acceleration are introduced in this paper。 And here we experimentally obtained highly-collimated argon ion beam (Ar16+) with narrow energy spread by irradiating a 45fs fully-relativistic laser pulse onto an argon cluster target。 The Ar16+ ion beam has a minimum absolute energy spread of 0。19MeV/nucleon at the energy peak of 0。39MeV/nucleon。 Besides, two-dimensional PIC simulations are also conducted to study the acceleration process。 It can be found that the argon ion beam undergoes a phase of coulomb explosion, and the laser wakefield has a strong modulation effect on the ion energy distribution by cutting off the low energy part。 Thus, the energy spread can be greatly reduced。 The experimental process can be well explained by the simulation。 Also, the PIC simulations verify the experimental results ideally。 In a word, high quality argon ion beam with narrow energy spread can be obtained in both experiments and simulations。

Keywords  ion acceleration; TNSA; coulomb explosion; laser wakefield modulation; PIC simulation 

目   次

1  绪论 1

2  超强激光与物质相互作用理论阐述 2

2。1  强激光与物质相互作用 2

2。2  基本方程和概念 4

2。3  数值模拟方法——PIC模拟 7

2。4  论文结构安排 8

3  超强激光加速离子 10

3。1  离子加速概述 10

3。2  离子加速实验现状