论文标题
针对平面发射增长问题的确切解决方案
Exact solutions to planar emittance growth problems
论文作者
论文摘要
本文是基于简单统计推理的发言性动力学理论的系列中的第一个。发射量是用于表征电子显微镜，光子源和颗粒梁的质量的中心量。高强度带电颗粒梁中的发射率生长是一个特别具有挑战性的非平衡统计物理问题，其中诸如无序诱导的加热和电荷重组之类的影响会导致发射和光束质量的迅速降解。自由能和熵的概念已被用来提高对发射动力学的概念理解。在这里，我们基于粒子分布的二阶累积理论开发理论，并使用此公式来精确解决几个维度问题。这些溶液是超快电子显微镜中使用的煎饼束的自由膨胀动力学现有结果的重要扩展，该动力学在短时间内随时间膨胀而膨胀[1-3]。在这里，我们表明，随着时间的二次多项式，严格平面扩展的平方发射量增加。我们将基于单个粒子轨迹的理论与基于分布的理论进行比较，并根据各个粒子轨迹扩展理论的基础，我们称之为“样本图片”。我们后来的工作使用此公式来得出广义的包膜方程，这些方程捕获了两个维度和三维系统中的发射剂增长效应。 1。B.J. Siwick，J。R。Dwyer，R。E。Jordan和R. J. Dwayne Miller，《应用物理学杂志》 92，1643（2002）。 2. B. W. Reed，《应用物理学杂志》 100，034916（2006）。 3。B.Zerbe，X。Xiang，C.-Y. Ruan，S。Lund和P. Duxbury，《物理审查加速器和光束》 21，064201（2018）。
This paper is the first in a series which develops the theory of emittance dynamics based on simple statistical reasoning. Emittance is a central quantity used to characterize the quality of electron microscopes, photon sources and particle beams. Emittance growth in high intensity charged particle beams is a particularly challenging non-equilibrium statistical physics problem in which effects such as disordered-induced heating and charge reorganization can lead to very rapid degradation of emittance and beam quality. The concepts of free energy and entropy have been utilized to improve conceptual understanding of emittance dynamics. Here we develop a theory based on the second order cumulant of particle distributions and use this formulation to exactly solve several one dimensional problems. These solutions are important extensions of the existing results for the free expansion dynamics of pancake bunches used in ultrafast electron microscopy, which at short times are known to expand quadratically with time[1-3]. Here we show that the squared emittance of a strictly planar expanding bunch increases as a quadratic polynomial of time. We compare theories based on individual particle trajectories with theories based on distributions and expand the foundations of theories based on individual particle trajectories, which we call the "sample picture". Our later work uses this formulation to derive generalized envelope equations which capture emittance growth effects in two and three dimensional systems. 1. B. J. Siwick, J. R. Dwyer, R. E. Jordan, and R. J. Dwayne Miller, Journal of Applied Physics 92, 1643 (2002). 2. B. W. Reed, Journal of Applied Physics 100, 034916 (2006). 3. B. Zerbe, X. Xiang, C.-Y. Ruan, S. Lund, and P. Duxbury, Physical Review Accelerators and Beams 21, 064201 (2018).
