Courant-Snyder invariant density screening method for emittance analysis

• Published in: Chinese physics C Vol. 35; no. 11; pp. 1059 - 1065
• Main Author: 孙纪磊 唐靖宇 敬罕涛
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.11.2011
• Subjects: Boundaries; Density; Emittance; Invariants; Mathematical analysis; Mathematical models; Particle beams; Screening; 光束参数; 发射率; 变密度; 均方根发射度; 带电粒子束; 应用程序代码; 特征描述; 筛选方法
• ISSN: 1674-1137; 0254-3052; 2058-6132
• DOI: 10.1088/1674-1137/35/11/015

Emittance is an important characteristic of describing charged particle beams. In hadron accelerators, we often meet irregular beam distributions that are not appropriately described by a single rms emittance or 95% emittance or total emittance. In this paper, it is pointed out that in many cases a beam halo should be described with very different Courant-Snyder parameters from the ones used for the beam core. A new method - the Courant-Snyder invariant density screening method - is introduced for analyzing emittance data clearly and accurately. The method treats the emittance data from both measurements and numerical simulations. The method uses the statistical distribution of the beam around each particle in phase space to mark its local density parameter, and then uses the density distribution to calculate the beam parameters such as the Courant-Snyder parameters and emittance for different beam boundary definitions. The method has been used in the calculations for beams from different sources, and shows its advantages over other methods. An application code based on the method including the graphic interface has also been designed.