Velocity Bunching Experiment at the Neptune Laboratory

Femtosecond Beam Generation

“…The first experiment to verify the velocity bunching concept was performed at the University of Califonia, Los Angeles, Particle Beam Physics Lab (UCLA-PBPL) [Musumeci (2002)l. Unfortunately, this was performed in a photoinjector layout not optimized to perform RF compression.…”

“…However, they measured a 0.39-ps bunch length after the linac by using a special filter model analysis of the autocorrelator signal, and they reconstructed by simulations the beam dynamics to show that the bunching was still a mixed one, i.e. velocity bunching in the P W T linac and ballistic in the following drift [Musumeci (2002)]. …”

“…This technique has been extensively explored by numerical simulation studies of the whole photoinjector system which generates ultrashort electron bunches up to 150 MeV ; Boscolo et al (2002)l. However, recently the first experimental confirmations of simulations and theoretical predictions have been observed at a number of laboratories [Piot et al (2002); Musumeci (2002); Musumeci and Rosenzweig (2003)l. Other experiments in the past showed some evidence of this process l. The promise is to attain 10-100-fs long bunches with charges ranging from 10 pC up to a few nC.…”

High Energy Gain of Trapped Electrons in a Tapered, Diffraction-Dominated Inverse-Free-Electron Laser

“…It has a very strong variation of the wiggling period and magnetic field amplitude along the axis (see Table I), carefully tailored to maintain the resonance condition of the IFEL interaction between the CO 2 photons and the quickly accelerating electrons. Because the Rayleigh range is much shorter than the undulator length, the driving field along the undulator varies rapidly, and it becomes important to properly consider the Guoy phase shift experienced by the laser near the focal point [14]. In order to maintain synchronism through the focal region, two undulator sections were built with the field in the central region adjusted using a corrector Vanadium-Permandur plate.…”

“…In order to maintain synchronism through the focal region, two undulator sections were built with the field in the central region adjusted using a corrector Vanadium-Permandur plate. The undulator period and field strength were specified using simulation results [11] obtained with the three-dimensional code TREDI [14].…”