RECENT RESULTS FROM AND FUTURE PLANS FOR THE VISA II SASE FEL

The VISA II (Visible to Infrared SASE Amplifier) project, a consequent experiment to the succesful VISA enterprise, entails the use of a chirped electron beam to drive a high gain SASE FEL. The resulting ultra-short pulses will be characterized using an advanced FROG (Fre-quency Resolved Optical Gating) technique, as well as a double differential spectrum (angle/wavelength) diagnos-tic. Implementation of sextupole corrections to the longitu-dinal aberrations affecting the high energy-spread chirped beam during transport to the VISA undulator is studied. Start-end simulations, including radiation diagnostics, are discussed. Initial experimental results involving a highly chirped beam transported without sextupole corrections, the resulting high gain lasing, and computational analysis are briefly reported