Two-Bunch Operation at the FERMI FEL Facility

Giuseppe Penco , Enrico Allaria , Silvano Bassanese , Paolo Cinquegrana , Stefano Cleva , Miltcho Danailov , Alexander Demidovich , Simone Di Mitri , Mario Ferianis , Giulio Gaio , David Gauthier , Luca Giannessi , Mauro Predonzani , Fabio Rossi , Eléonore Roussel (1) , Simone Spampinati , Mauro Trovò

1 PhLAM - Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523

FERMI is a linac-driven free electron laser (FEL) based upon the High Gain Harmonic Generation (HGHG) scheme. In standard conditions a bunch of 700 pC of charge with sub mm-mrad emittances is accelerated to 1.2-1.5GeV in a normal conducting S-band linac and drives FEL-1 or FEL-2 undula-tor line, which lase respectively in the range 100-20nm or 20-4nm. A number of two-color schemes have been implemented at FERMI for pump/probe experiments, all consisting in making two portions of the same electron bunch lase at two different wavelengths, with a time-separation from 0 to few hundreds of fs. In order to increase the time separation to ns and tens of ns we have explored the acceleration of two inde-pendent electron bunches separated by multiple of the linac main radio-frequency period, i.e. 333ps. Measure-ments and characterization of this two-bunch mode oper-ation are presented, including trajectory control, impact of longitudinal and transverse wakefields on the trailing bunch and manipulation of the longitudinal phase space.

Mots clés: linac; wakefield; laser; FEL; electron

Domaines: Physique des accélérateurs [physics.acc-ph]

Giuseppe Penco, Enrico Allaria, Silvano Bassanese, Paolo Cinquegrana, Stefano Cleva, et al.. Two-Bunch Operation at the FERMI FEL Facility. 8th International Particle Accelerator Conference, May 2017, Copenhagen, Denmark. pp.WEPAB037, ⟨10.18429/JACoW-IPAC2017-WEPAB037⟩. ⟨hal-01645996⟩