Recent progress in emittance control of the photoelectron beam using transverse laser shape modulation and tomography technique

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 multidimensional 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. A relatively measurement time (approximately 30 minutes) was improved by installing Hall probes into each quadrupole magnet. This eliminated the necessity to degauss all quadrupoles between each measurement point. Additional phase control of the RF system and driving laser should also improve confidence in 5 dimensional phase space reconstruction