超短超强激光驱动的离子加速相关问题研究
文献类型：学位论文
| 作者 | 裴之坤 |
| 文献子类 | 博士 |
| 导师 | 沈百飞 |
| 关键词 | 离子加速 ion acceleration 光压 light pressure 打孔过程 hole-boring process PIC(particleincell) PIC(particle-in-cell) |
| 其他题名 | Ion acceleration generated by Ultra-Short and Intense Lasers |
| 英文摘要 | 高品质离子源在众多领域有着重要的应用，而强激光驱动的离子源有着超短、超快、高亮度以及低发射度等优秀的特性，近年来激光技术的进步让激光等离子体加速得 到的离子束无论在理论还是实验方面都有着令人振奋的进展。为了提高被加速离子的能量、能散等品质，研究者们对超强激光与等离子体相互作用的物理过程进行了深入的理论研究，提出了各种加速机制，包括靶后鞘层加速机制 (TNSA)、无碰撞静电激波加速机制 (CSA)、光压加速机制 (RPA) 等等。虽然部分加速机制已经有着比较完善的理论模型，甚至已经在实验上得到了验证，目前受限于激光技术以及理论模型对加速效果的限制，激光离子加速能达到的最高能量仍然距传统加速器有相当的差距。鉴于光压加速在众多加速机制中是比较有可能突破目前加速能量限制的一种加速机制，本论文对光压加速机制进行了比较深入的理论研究。最后对激光驱动的离子束应用于反质子产生做了一些初步的模拟工作。本论文主要做了以下几个方面的工作: 1. 提出了一种质子的级联光压加速机制，当强激光的光压驱动着一个薄膜靶在以光速前进时，这时若一束高能质子束入射到由光压产生的高速移动的强静电场 中，质子会被加速到更高的能量。由一维模拟结果以及解析结果可以看出，一束 3 GeV 的质子束可以被加速到 7 GeV，并且质子束的能散会得到大幅改善，也就是说一级级联加速可以将质子束的能量提高 4 GeV。二维模拟结果再次验证了这 种级联加速的方式的有效性。这种机制提供了一种在GeV 量级上使质子束能量随激光能量线性提高的方法，这是一种很有希望得到数十GeV 的质子束的方法。 2. 将强电磁波与过临界冷等离子体的解析理论推广到准稳态情况。通过参量变换并 考虑边界条件，得到了打孔 (hole-boring) 过程的准稳态解。由理论分析得到了过程中对应的电场以及粒子密度分布，相比与动力学描述方法，准稳态理论给出了更多的细节信息。一维 PIC(particle-in-cell) 模拟结果与理论结果的精确吻合证实了这一理论的有效性。这一准稳态流体理论或许可以为理解光压加速离子的基础 机制提供帮助。 3. 使用Geant4 蒙特卡洛模拟软件配合 PIC 模拟对激光驱动离子束轰击金属靶产生反质子的过程进行数值模拟。探讨了激光驱动的离子源用于产生反质子的可行性。; High-quality ion source has important applications in many fields, and ion source driven by ultra-strong laser has excellent characteristics of ultra-short,ultra-fast,high brightness and low emissivity. In recent years,advances in laser technology have led to exciting progress of laser plasma driven ion beam in both experimental and theoretical aspects.In order to improve the quality of accelerated ions, the researchers have carried out in-depth theoretical research on the physical process of ultra-strong laser interaction with plasma. Various accelerating mecha- nisms have been proposed,including the target normal sheath acceleration(TNSA),collisionless electrostatic shock acceleration mechanism(CSA), Radiation pressure acceleration(RPA) and so on. Although aome of the accelerating mechanisms already have a relatively complete theo- retical model, and enven have experimentally verified,currently limited by the laser technology and the restriction of theoretical model,there is still a condiderable gap between laser ion accel- eration and the traditional accelerator. In wiew of the fact that the radiation pressure accleration mechanism is more likley to break though the current energy limit,this thesis carries out a in- depth theoretical study of the radiation pressure acceleration mechanism. The last parti of the thesis is some preliminary simulation work of the laser-driven ion beam been applied to the antiproton production. This thesis mainly does the following work: 1.A cascaded radiation-pressure acceleration scheme is proposed. When an energetic proton beam is injected into an electrostatic field moving at light speed in a foil accelerated by light pressure, protons can be re-accelerated to much higher energy. An initial 3-GeV proton beam can be reaccelerated to 7 GeV while its energy spread is narrowed significantly, indicating a 4-GeV energy gain for one acceleration stage, as shown in one-dimensional simulations and analytical results. The validity of the method is further confirmed by two-dimensional simulations. This scheme provides a way to scale proton energy at the GeV level linearly with laser energy and is promising to obtain proton bunches at tens of gigaelectron-volts. 2.We present a quasi-stationary fluid theory to precisely describe the hole-boring process. The corresponding distributions of the electrostatic field and the particle density are theoretically obtained, which give more details than the previous stationary theory. The theoretical result is confirmed by one-dimensional particle-in-cell simulations. Such quasi-stationary fluid theory may help in understanding the basic mechanisms of ion acceleration in the radiation pressure acceleration. 3.The process of laser driven ion beam interacting with metal target and producing antipro- tons is simulated using the Geant4 Monte Carlo simulation software with PIC simulation method. The feasibility of the laser driven ion source for the generation of antiproton is discussed. |
| 学科主题 | 光学 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31012]  |
| 专题 | 中国科学院上海光学精密机械研究所 |
| 作者单位 | 中国科学院上海光学精密机械研究所 |
| 推荐引用方式 GB/T 7714 | 裴之坤. 超短超强激光驱动的离子加速相关问题研究[D]. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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