Study on the Effect of Solenoid Magnetic Field on Beam Quality in Velocity Bunching

• Main Authors: Wen, Yung-Hsiang, 溫詠翔
• Other Authors: Lau, Wai-Keung
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/32w5g4

碩士 === 國立清華大學 === 先進光源科技學位學程 === 106 === Space-charge effect is not negligible during the early stage of beam acceleration in a photoinjector rf linac that is operated for generation of short electron pulses by velocity bunching. A solenoid with iron shield can be used to provide the required axis-symmetric magnetic field to balance the radial space-charge force. However, the iron shield cannot be perfectly symmetric because openings are reserved for feeding water pipes and electrical cables to the coils. In addition, alignment errors of the solenoid may also spoil the symmetry of the system. In this study, simulation are carried out to optimize electron beam quality at linac exit and investigate how does the non-axisymmetric solenoid field of different origins influence beam properties, such as beam size, transverse emittance during the rf bunch compression. Beam size and transverse emittance are measured to check the adequacy of the linac solenoid magnet design.