PLASMA ACCELERATION EXPERIMENT AT SPARC LAB WITH EXTERNAL INJECTION

Abstract

At the SPARC LAB facility of INFN-LNF we are installing two transport lines for ultra-short electron bunches and an ultra-intense laser pulses, generated by the SPARC photo-injector and by the FLAME laser in a synchronized fashion at the tens of fs level, to co-propagate inside a hydrogen filled glass capillary, in order to perform acceleration of the electron bunch by a plasma wave driven by the laser pulse. The main aim of this experiment is to demonstrate that a high brightness electron beam can be accelerated by a plasma wave without any significant degradation of its quality. A 10 pC electron bunch, 10 fs long is produced by SPARC and transported to injection into the capillary, which is 100 micron wide, at a gas density around 1017cm−3. The laser pulse, 25 fs long, focused down to 65 microns into the capillary is injected ahead of the bunch, drives a weakly non-linear plasma wave with wavelength of about 130 microns. A proper phasing of the two pulses allows acceleration of electrons from the injection energy of 150 MeV up to about 570 MeV for a 8 cm long capillary. Installation of the beam lines is foreseen by the end of 2012 and first tests starting in mid 201