靶的密度分布对激光等离子体质子加速的影响研究

发布时间：2018-04-06 23:13

本文选题：超强超短激光脉冲　切入点：等离子体　出处：《东北石油大学》2015年硕士论文

【摘要】：近年来,高能的离子束,尤其的高能质子束在质子快速成像、癌症的治疗方面以及质子加热等领域发挥了重要的作用。因此获得高品质的离子束成为专家学者所不断追求的目标。因此在过去的几十年里,物理学家们一直致力于在寻找更短距离加速粒子方案,期望能在较小的范围内收获更高的粒子能量。伴随科技的进步,CPA技术的迅速发展,在现有的激光器上已经可以获得飞秒量级的超强超短激光脉冲,这样的激光所形成的激光场强远远超过了原子内部的场强。强激光、等离子体二者的相互作用时,往往伴随着高达GV/m~TV/m量级的强纵向静电场,科研工作者就可以用这些电场可以来加速电子、质子或离子,并采用这种方法开发小型化的粒子加速器。目前,激光等离子体加速产生质子在实验上已取得一些成果,但在由于相对论效应、群体效应、湍流等因素的影响,加速处的质子束流品质不高,所以仍有需要研究工作需要完成。本文基于一维的粒子云网格(Particle-In-Cell,PIC)计算机模拟,通过改变靶的密度,研究靶密度分布对激光等离子体质子加速的影响,在本模拟中采用ROOT软件对所产生的超大数据进行处理并产生加速粒子速度分布,更清晰准确的了解到靶密度分布对结果的影响。在本文中经过激光参数,靶参数的初步筛选,而后对靶形状进行初步的选择,确定在一维情况下表现较为出色的密度梯度靶型。在对三种激光脉冲形状筛选后发现sin2型的激光同靶相互作用时所产生的质子速度较高,而在三种靶中又以凸型密度梯度靶所产生的质子束品质最好。因此在研究中着重的对sin2型激光与凸型密度梯度靶相互作用进行了研究,在改变靶密度的过程中发现了一种凸型密度靶与sin2型右旋圆偏振激光相互作用所产生的质子束流能量达到316.92 MeV,通过一维PIC模拟,找到了有利于质子加速的靶密度分布,从而为激光等离子体质子加速实验研究提供了一定的理论指引。
[Abstract]:In recent years, high energy ion beam, especially the high-energy proton beam in fast imaging and proton proton treatment, heating and other fields of cancer has played an important role. So the ion beam to obtain high-quality experts and scholars have become the pursuit of the goal. So in the past few decades, physicists have been looking for a shorter the distance is expected to accelerate particles, higher energy particles results in a smaller range. With the progress of science and technology, the rapid development of CPA technology, ultrashort laser pulse in the existing laser can obtain femtosecond laser intensity, the formation of such laser is far more than the field inside the atom laser. Two, the interaction of plasma, often accompanied by strong vertical electrostatic field up to the magnitude of GV/m~TV/m, researchers can use the electric field can be accelerated The electron, proton or ion, and using this method to develop miniaturized particle accelerators. Currently, laser plasma acceleration of protons produced some achievements have been obtained in the experiment, but due to relativistic effects, group effect, effect of turbulence and other factors, accelerate the proton beam quality is not high, so there is still a need to work needs to be done. In this paper, based on one-dimensional particle cloud grid (Particle-In-Cell, PIC) computer simulation, by changing the density of the target, study on the effect of target density distribution of laser plasma acceleration of protons in the simulation by ROOT software on large data generated by the processing and accelerate the particle velocity distribution more clearly and accurately understand the target density distribution of the results. In this paper through the preliminary screening of the laser parameters, target parameters, and then carry out the preliminary selection of target shape, identified in the one-dimensional case The density gradient target more outstanding performance. In three to find the laser interaction with the target of the sin2 type proton high speed laser pulse shape screening, proton beam quality in the three target in the convex density gradient generated by the best target. Therefore in the study of a heavy sin2 laser interaction with convex target density gradient were studied in the process of changing the target density was found in a proton density target and convex type sin2 right circularly polarized laser caused by the interaction of beam energy of 316.92 MeV, the one-dimensional PIC simulation, find the target for proton density distribution the speed, in order to provide theoretical guidance for the experimental study of laser plasma proton acceleration.

【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN24

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