Author: Yamashita, H.
Paper Title Page
Image Charge Effect on Emittance Reduction Phenomenon in Electron Gun  
  • T. Nogi
    Kyoto Univeristy, Kyoto, Japan
  • T. Katsurayama, T. Kii, K. Masuda, K. Morita, T. Murata, K. Nagasaki, H. Ohgaki, S. Suphakul, K. Torgasin, H. Yamashita, H. Zen
    Kyoto University, Kyoto, Japan
  Development of next generation light sources requires reduction of beam emittance. The emittance can be influenced in the vicinity of a cathode, where electron energy is low and the beam dynamics is dominated by space charge and image charge effect. Recently it was discovered that for ideal DC acceleration emittance rises near cathode and subsequently decreases due to self-linearization force caused by space charge effect [*]. This phenomenon occurs for accelerating field, which is lower than usually applied at conventional electron guns. It is an issue that this concept is feasible for electron gun configuration of real injectors. In this research we numerically investigate the transverse emittance and its dependence on parameters such as current density, accelerating field and the distance from the cathode. As a result, the position of minimal emittance was found to be correlated to perveance. This position can be varied by proper settings of parameters. In this conference, we will present these phenomena seen numerically in the SCSS thermionic gun geometry.
* A. Mizuno, et al., Nucl. Instr. Meth. Phys. Res. A 774 (2015) 51-59.
slides icon Slides TUC04 [1.604 MB]  
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