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chi20191128上海光机所沈百飞557643Since Maiman invented the first laser in the world in 1960, laser has made remarkable progress. The Chirped pulse Amplification (CPA) technique has revolutionized the enhancement of laser intensity. In 2006, Shanghai Ultra-intense and Ultra-short Laser Experimental Facility (SULF) has achieved an unprecedented 5.3 patawatt (PW) of laser power output, where its pulse duration is less than one trillionth of a second. In 2019, SULF has reached 10 PW scale of peak power, which is 1,000 times the total power of the global power grid. The emergence of ultra-short and ultra-intense lasers has provided unprecedented extreme physical conditions and new experimental approaches for mankind. With the continuous improvement of laser intensity, it is possible to realize a series of extreme physics such as ultra-strong electric and magnetic fields, ultra-high acceleration gradient and energy density in the laboratory. In the process of intense laser-matter interaction, the matter is ionized, where the parameters of plasma pressure, temperature and density are similar to those of plasma in astrophysics. Theses parameters are appropriate to simulate the physical conditions of the formation of jet, magnetic reconnection and nuclear state change in astrophysics. Meanwhile, Allen et al. firstly proposed the vortex light with orbital angular momentum (OAM), which has one degree of freedom compared with ordinary lasers. This OAM broadens the application of laser in optical tweezers, optical manipulation, optical communication, cold atomic physics, astrophysics and so on. Based on the above background, this thesis focuses on the following work, 1. Under the applied electrostatic field (10^4~10^12 V/m) and magnetostatic field (11 T), collimated electron jets are generated from the cylindrical plasma. Through 3D PIC(Particle in Cell) simulation, it is found that the applied magnetostatic field contributes significantly to the jet collimation, whereas the applied electrostatic field plays a vital role in the jet formation. Compared with the intense magnetic field conditions in celestial bodies produced by the intense laser-plasma interaction, the self-evolution conditions of the electrostatic and magnetrostatic fields applied here are closer to the physical conditions of celestial bodies, which can further provide the reference for the mechanism of celestial jet. When a 2 ps delay of the magnetostatic field is set with respect to the applied electrostatic field Emax=3*10^9 V/m, the longitudinal electron momentum Px could reach 0.7 mec, and the total charge of the ejected electrons (with energy above 10 keV) could be 3.2*10^(-9). 2. Orbital angular momentum (OAM) originates from the helical phase factor of laserexp(il*phi), and its direction is generally parallel to the propagation direction of laser. High-order vortex harmonics carrying OAM, with the direction unparallel to propagation direction of the vortex harmonics, are generated by the intense vortex laser-plasma grating interaction. The numerical relationship among the transverse average OAM, the harmonic order and the diffraction angle is studied and ascertained. By changing the grating period, the transverse OAM of the vortex harmonic can be adjusted. Carrying tilted total OAM with respect to the propagation direction, the high-order vortex harmonics could enlarge the existing application area. For example, the transverse OAM would open new avenues in optical trapping and particle manipulation. As the transverse OAM of the beam could be transferred to a trapped particle, the transverse rotation would provide additional rotational degrees of freedom in optical tweezers. 3. The OAM and spin angular momentum (SAM) of high-order harmonics generated by intense elliptically polarized vortex laser interacting with a planar target are studied. Based on PIC simulation, the angular momentum of vortex harmonics is calculated. Combined with the characteristics of electric field distribution of vortex harmonics, we try to find out the relationship among OAM, SAM and ellipticity.2020atalunwen2217223431712Electromagnetostatic Field; electron jets; intense vortex laser; plasma grating; transverse orbital angular momentumResearch on the Electron Jets and Transverse Orbit Angle Momentum of Intense Vortex Laser电子喷流以及强涡旋激光的横向轨道角动量研究自1960年梅曼成功研制出世界上第一台激光器以来,激光得到了显著的发展,特别是啁啾脉冲放大(CPA) 技术革命性地推动了激光强度的提升。2016年上海超强超短激光实验装置(SULF)获得了史无前例的5.3拍瓦激光功率输出,其脉宽持续时间小于万亿分之一秒。2019年又实现了10拍瓦级峰值功率,这一数值相当于全世界电网功率总和的1000倍。超短超强激光的出现,为人类提供了前所未有的极端物理条件与全新实验手段;激光强度的不断提高,使实验室实现瞬态的超强电场、超强磁场、超高加速梯度、超高等离子体能量密度等一系列极端物理成为可能。强激光与物质的相互作用过程中物质被电离,其产生的等离子体压强、温度、密度等参数与一些天体物理中的等离子体参数相近,可以很好的模拟天体物理中喷流、磁重联、星体内核物态变化产生的物理条件。同时Allen等人首次提出了携带轨道角动量(OAM)的涡旋光,相对于一般的激光多了一个自由度,拓宽了激光在光镊、光学操控、光通信、冷原子物理、天体物理等方面的应用。 基于以上背景,本论文主要做了以下工作: 1. 在外加静电场(10^4~10^12 V/m)和静磁场(11 T)的条件下,圆柱等离子体产生准直的电子喷流。通过3D PIC (Particle in Cell)模拟,发现外加径向静电场在喷流形成过程中起着重要的作用,外加轴向静磁场有助于喷流的准直。相对于强激光与等离子体相互作用产生天体中类似的强磁场条件,此工作中利用的外加静电磁场的自演化条件更接近于天体中的物理条件,能进一步为天体喷流的产生机制提供参考。基于静电场、静磁场在喷流形成过程中的作用,将外加静磁场延迟2 ps(相对于外加静电场Emax=3*10^9 V/m)作用到等离子体上,可以产生纵向动量达到0.7 mec、总电荷量达到3.2*10^(-9)(能量高于10 keV的喷出电子)的高能高电荷量的准直的电子喷流。 2. 轨道角动量(OAM)来源于激光螺旋相位因子exp(il*phi), 其方向一般与激光的传播方向平行。利用强涡旋激光与等离子体光栅相互作用,产生带有不平行于谐波的传播方向的OAM的高次涡旋谐波。研究并确定了横向 的平均OAM与谐波阶次、衍射角之间的数值关系。通过调节光栅常数, 可以调节产生的涡旋谐波的横向OAM。携带倾斜OAM的高阶涡旋谐波,可以拓宽强涡旋激光现有的应用领域并产生新的应用。例如,横向OAM可以在光学捕获以及粒子操控方面另辟蹊径,因为横向OAM作为光束新增的自由度传递给被捕获的粒子,这样在光镊中可以提供额外的旋转自由度。 3. 研究强椭圆偏振涡旋激光与平面靶相互作用中,产生的高次谐波所携带的OAM和自旋角动量(SAM)。通过PIC模拟数据计算产生涡旋谐波的角动量,结合涡旋谐波的电场分布特点,试图找出OAM、SAM以及椭圆偏振率之间的关系。静电磁场;电子喷流;强涡旋激光;等离子体光栅;横向轨道角动量中国科学院上海光学精密机械研究所邱晶等离子体物理博士
中文题目: 电子喷流以及强涡旋激光的横向轨道角动量研究
外文题目: Research on the Electron Jets and Transverse Orbit Angle Momentum of Intense Vortex Laser
作者: 邱晶
导师姓名: 沈百飞
学位授予机构: 中国科学院上海光学精密机械研究所
答辩时间: 20191128
中文关键词:
静电磁场;电子喷流;强涡旋激光;等离子体光栅;横向轨道角动量
英文关键词:
Electromagnetostatic Field; electron jets; intense vortex laser; plasma grating; transverse orbital angular momentum
中文摘要:
英文摘要:
文献类型:学位论文
学位级别: 博士
正文语种: chi
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