| 题名 | 超强超短激光驱动的尾波场电子加速及新型辐射源研究 |
| 作者 | 余昌海 |
| 文献子类 | 博士 |
| 导师 | 刘建胜 |
| 关键词 | 超强超短激光 ultra-intense ultra-short laser pulse 激光级联尾波场加速 laser cascaded wakefield acceleration 能量啁啾控制 energy chirp control 高品质电子束 high-quality electron beam Compton散射 Compton scattering 等离子体摇摆器 plasma wiggler betatron辐射 betatron radiation 等离子体通道 plasma channel 打洞效应 hole boring |
| 其他题名 | Study of Wakefield Electron Acceleration and Novel Radiation Sources based on Ultra-intense Ultra-short Laser |
| 英文摘要 | 超强超短激光的迅猛发展，为人类提供了前所未有的全新实验手段和极端物理条件。超强超短激光可将物质迅速电离成等离子体，光与物质的相互作用进入了相对论非线性光学的全新范畴。超强超短脉冲激光驱动的等离子体尾波内可维持的加速电场达100GV/m量级，比传统的电子加速器提高三个数量级以上，可在厘米量级的加速长度内得到GeV量级的高能电子束输出，从而极大地降低加速器的规模和成本。近年来激光粒子加速器得到长足的进步和发展，在驱动新型辐射源方面具有广泛应用前景和巨大潜力，可为高能粒子物理学、核光子学、材料科学、生物医学等前沿交叉基础研究提供新手段和新机遇。因此，基于超强超短激光等离子体相互作用驱动的激光粒子加速器和新型辐射源等方面的研究，不仅对等离子体物理与强场光学物理领域的重要基础物理研究有重大的科学意义，而且具有巨大的实际应用前景。 本论文开展了超强超短激光驱动的激光级联尾波场加速高品质电子束、新型辐射源以及激光在不同密度等离子体中传输特性和通道产生的研究，并在激光尾波场加速高品质电子束、自同步康普顿散射产生超高亮度伽玛射线源、激光尾波场中操控低能散电子束增强betatron辐射、强激光在不同等离子体中的传输特性、通道产生、打洞效应等方面取得了如下创新成果： 1.参与搭建了百TW超强超短激光驱动级联尾波场电子加速产生高品质电子束及波荡器辐射出光的实验研究平台。通过构造特殊结构的气体密度分布，控制种子电子束注入、能量啁啾能量控制、电子能散压缩，在实验上成功获得了峰值能量在200～600 MeV范围，能散0.4-1.2%，电量10-80 pC，发散角0.1-0.3 mrad的高品质单能电子束。电子束最高的六维相空间亮度达到6.5x10^15A/m^2/0.1%，远高于目前国际上报道的同类研究结果。 2.搭建了利用超强超短激光驱动的全光自同步逆康普顿散射方案产生超高亮度伽玛射线源的实验研究系统。基于新型级联尾波场加速方案，获得了峰值能量在150~500 MeV范围，rms能散~1%，电量~50pC，发散角<0.4 mrad，脉宽~10fs的高品质电子束；然后利用等离子体中出来的激光快速离化20μm钛膜形成的等离子体镜来反射驱动激光，与电子束实现自同步精确对撞，产生了峰值能量在0.3-2MeV范围可调谐的准单色伽玛射线源，其峰值亮度高达3×10^22photons s^-1 mm^-2 mrad^-2 0.1%BW，比国际上报道的同类伽玛射线源亮度相比高出一个量级以上。同时单发伽马光子数达到5×10^7光子，可与目前国际上几类大型传统伽马射线源光子通量相媲美。结合相关的模拟，详尽分析了这种自同步康普顿散射过程中电子束的演化和其他辐射的影响以及伽玛射线能谱特性等相关物理问题。 3.提出了基于超强超短激光驱动的等离子体摇摆器中操控电子束横向振动获得高亮度高能x射线辐射源的新方案。通过引入一特定结构的等离子体密度分布，实现了低能散度电子束的产生和横向振动的独立控制。在不破坏电子束能散度的条件下，显著增强了betatron辐射的光子产额和能量。PIC模拟结果验证了相关的物理图像：由于驱动激光的折射引起电子束在尾波场中横向振动振幅的增强，并能在扭摆器中周期地辐射高能x射线，同时实现了将高品质电子束的产生、电子束横向振动的操控以及扭摆器辐射三个过程融为一个整体。 4.开展了超强超短激光在低密度或近临界等离子体中自聚焦产生等离子体通道的实验研究，通过选取合适的等离子体密度以及优化激光导引，产生了长距离、宽横向宽度、边沿极陡峭分布(~10^23 cm^-4)的等离子体通道。通过密度干涉诊断对等离子体密度分布特性和演化过程进行测量，获得了通道产生的时间和空间信息。结合PIC模拟，对该机制下激光传输，电子、离子运动特性以及通道产生等进行了详细的分析和验证。 5.提出了一种利用双色超强超短激光在稠密等离子体中增强打洞效应以及提高激光传输和能量转换效率的新方案。通过引入短波长极紫外超强超短激光预先在稠密等离子中打洞并形成锥形分布的的预先中空通道，然后再将长波长的主驱动脉冲激光引入到中空通道中进行更长距离的传输和能量输运。结合PIC模拟和理论分析讨论了双色激光打洞机制下的电子、离子动力学特性和激光能量转换效率等相关物理问题。; The rapid development of the ultra-intense and ultra-short laser provides an unprecedented new experimental means and extreme physical conditions as never before. Ultra-intense ultra-short laser pules can quickly ionize the materials into plasma, leading the laser-mater interaction to the highly relativistic nonlinear optical regime. The plasma wakefield driven by an ultra-intense ultra-short laser pulse can maintain a high accelerating gradient on the order of 100Gv/m, three orders of magnitude greater than conventional accelerators. It can produce the GeV-class high-quality electron beams over a distance of centimeter-scale, which will greatly reduce the size and cost of the accelerators. As laser-based particle accelerator has made great progress and development in these recent years, it holds a wide range of prospects and great potential in driving novel radiation sources, which both provide new means and opportunities for high-energy particle physics, nuclear photonics, materials science, biomedicine and other frontier basic research. Therefore, the study of laser-based particle accelerator and new radiation source based on the ultra-intense ultra-short laser-plasma interaction not only has great scientific significance for the basic phycial research of the plasma physics and strong field of optical physics, but also holds a huge practical application prospect. In this thesis, high-quality electron beams generation from the laser-wakefield accelerators, ultrahigh brilliant gamma-ray source from the self-synchronized Compton scattering, enhanced betatron radiation by steering a low-energy-spread electron beam in a laser-driven plasma wiggler, intense laser propagating features in different plasmas, laser channeling and hole boring have been studied. Some original results have been achieved, which are listed as below: 1.As a main contributor, an experimental platform for investigating high-quality electron beams acceleration from the cascaded wakefield and undulator radiation has been built up based on a hundred-terawatts (TW) ultra-intense ultra-short laser system. By constructing a special structure of the gas density distribution, the seed electron beam injection, energy chirp energy control and energy spread compression have been realized. In the experiments, high-quality electron beams with peak energies tunable from 200 to 600MeV has been obtained successfully, which possessed rms energy spread of ~1%, interated charges of 10~80pC, rms divergence angle of 0.1~0.3mrad. The maximum six-dimensional brightness is estimated as 6.5x10^15A/m^2/0.1% and much higher than the similar results reported in the world. 2.Ultrahigh brilliance quasi-monochromatic MeV gamma-rays based on self-synchronized all-optical Compton scattering has been demonstrated. Using the new cascaded wakefeild acceleration scheme, we have firstly generated the high-quliaty electron beams with peak energies tunable from 150 to 500 MeV, which possessed rms energy spread of ~1%, average interated charges of ~50 pC at the peak energy, rms divergence angle of <0.4 mrad and the duration of ~10 fs. Then the driving laser can rapidly ionize the 20-μm-thick Ti film to form a plasma mirror to reflect itself, and collide self-synchronously with the following electrons precisely. In the experiments, we have produced tunable (peak energy at 0.2~3MeV) quasi-monochromatic MeV gamma-rays with a peak brilliance of ~3×10^22photons s^-1 mm^-2 mrad^-2 0.1%BW. To the best of our knowledge, it is one order of magnitude higher than ever reported value of its kinds in the MeV regime. And the photon flux was as high as 5×10^7 photons/per shot, comparable to the state-of-the-art Compton scattering sources based on the conventional accelerators in the world. Backed by the exhaustive simulations and theoretical analysis, the physical pictures on the evolution of the electron beam, the influence of irrelevant emission during the self-synchronized Compton scattering process and the characteristics of gamma-ray spectra have been analyzed in detial. 3.A new scheme to enhance the betatron radiation by manipulating transverse oscillation of the electron beam in a ultra-intense ultra-short laser-driven plasma wiggler has been proposed. By producing a specific structure of the plasma density, the generation of electron beam and transverse oscillation can be controlled independently. We have successfully steer the transverse oscillation of the low-energy-spread electron beam to increase the betatron radiation photon yield and energy without deteriorating the energy spread of electron beam. The PIC simulation results have validated the related physical pictures: the accelerated electron beam can acquire a much larger transverse oscillation amplitude due to the refraction at the boundaries of the slanted plasma slab, high energy x-rays can be emitted by wiggling the electrons in a plasma wiggler regime. In this scheme, the high-quality electron beam generation, the manipulation of the e-beam transverse oscillation and the radiation in the wiggler have been realized as a whole. 4.The experimental study on the plasma channel due to the ultra-intense ultra-short laser self-focusing were investigated in the gas density or near-critical density plasmas. By appropriately selecting the plasma density and optimizing the laser pulse guiding, a clear plasma density channel longer than 300μm and wider than 25μm has been achieved, with a radial electron density gradient of ~10^23 cm^-4 at the channel walls. With the measurement of the density discribution and laser-plasma evolution from a pump-probe interferometry, the detailed time- and space-resolved information on the plasma channel has been obtained. Combined with the PIC simulations, nonlinear laser propagation, kinetic motion of electrons and ions, as well as the plasma channel formation, have been analyzed and verified in detail. 5.A new scheme of using two-color ultra-intense ultra-short laser pulses for enhanced hole boring into overdense plasma, as well as laser propagation and energy transferring efficiency, has been proposed. By presenting an ultra-intense ultra-short hole-boring laser pulse with a short central wavelength in extreme ultraviolet range to form the preformed hollow channel, the main infrared driving laser pulse can then be guided in the hollow channel for a longer-distance propagation and energy transport. In this scheme, the related issues such as the kinetic dynamics of the electron and ion, laser energy conversion efficiency are also discussed based on the PIC simulations and theoretical analysis. |
| 学科主题 | 光学 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/30938]  |
| 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 | 余昌海. 超强超短激光驱动的尾波场电子加速及新型辐射源研究[D]. |
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