ALFA, Feasibility Study of an Electron Pulse Stretcher to Increase the Duty Factor of the Frascati Linac

The present duty-factor of the 400 MeV Frascati National Laboratories Linac (8x10-4) can be made to approach unity by using an electron storage ring as a pulse stretcher: resonant extraction near an m/3 resonance by means of sextupolar nonlinearities in the ring allows slow extraction of the stored current with small energy spread. The feasibility of a machi ne, capable of 100¿A average current and 10-3 energy spread between 200 and 500 MeV is investigated. The optical structu re of a ring, 120 m long with a 5 m bending radius, is presen ted. The necessary modifications to the Linac are indicated. Expected parameters of the extracted beam are presented.