Recent Progress in Emittance Control of the Photoelectron Beam Using Transverse Laser Shape Modulation and Tomography Technique

摘要

A low emittance beam is very important for many applications, such as short-wavelength Free-Electron Lasers. A diagnostic that provides detailed information on the density distribution of the electron bunch in multi-dimensional phase-space is an essential tool for obtaining small emittance at a reasonable charge. Accurate phase space reconstruction and an analysis using a transport line with nine focusing magnets and techniques to control the optical functions and phases was demonstrated in previous publication. Relatively long time of measurements (approx. 30 minutes) was improved by installing Hall probes into each quadrupole magnet. This eliminated necessity to degauss all quadruples between each measurement points. Additional phase control of RF system and driving laser should also improve confidence in 5 dimensional phase space reconstruction.