UCLA, Los Angeles, California
INFN/LNF, Frascati (Roma)
Rome University La Sapienza, Roma
A unique SW/TW hybrid photoinjector are being developed under the collaboration of UCLA, LNF/INFN, and University of Rome. It can produce 240-fs (rms) bunch with 500 pC at 21 MeV. The bunch distribution has a strong spike (54 fs FWHM) and the peak current is over 2kA. As the bunch form factor at 1 THz is 0.43, it can produce coherent radiation at 1 THz. We are considering three types of way to generate it; coherent Cherenkov radiation (CCR), superradiant FEL, and coherent transition/edge radiation (CTR/CER). CCR used hollow dielectric with the outer surface metallic-coated. OOPIC simulation showed 21 MW of the peak power (5 mJ) at 1 THz. For FEL and CTR/CER simulation, QUINDI, which was written at UCLA to solve the Lienard-Wiechert potential, was used to calculate the radiation properties. In the contrast to CCR, their spectra were broad and their pulse lengths were short. They will be useful for fast pumping.
INFN/LNF, Frascati (Roma)
Istituto Nazionale di Fisica Nucleare, Milano
Università di Roma I La Sapienza, Roma
INFN-Roma II, Roma
Università di Roma II Tor Vergata, Roma
University of Rome La Sapienza, Rome
Rome University La Sapienza, Roma
ENEA C.R. Frascati, Frascati (Roma)
The region of the spectrum from 0.3 to 5 THz is of great interest for several experiments in different areas of research. A THz radiation source can be produced at SPARC as coherent transition radiation emitted by either a compressed or longitudinally modulated beam intercepting a metal foil placed at 45° with respect to the beam propagation. Results on the characterization of the THz source at SPARC are described in the paper.
INFN/LNF, Frascati (Roma)
Istituto Nazionale di Fisica Nucleare, Milano
INFN-Roma II, Roma
ENEA C.R. Frascati, Frascati (Roma)
University of Rome La Sapienza, Rome
INFN-Roma, Roma
UCLA, Los Angeles, California
JASRI/SPring-8, Hyogo-ken
PSI, Villigen
The primary goal of the SPARC project is the commissioning of the SASE FEL operating at 500 nm driven by a 150-200 MeV high brightness photoinjector. Additional experiments are foreseen also in the HHG Seeded configuration at 266, 160 and 114 nm. A second beam line hosting a THz source has been recently commissioned. The recent successful operation of the SPARC injector in the Velocity Bunching (VB) mode has opened new perspectives to conduct advanced beam dynamics experiments with ultra-short electron pulses able to extend the THz spectrum and to drive the FEL in the SASE Single Spike mode. Moreover a new technique called Laser Comb, able to generate a train of short pulses with high repetition rate, as the one required to drive coherent plasma wake field excitation, has been tested in the VB configuration. The energy/density modulation produced by an infrared laser pulse interacting with the electron beam near the cathode has been also investigated. In this paper we report the experimental results obtained so far and the comparison with simulations.
INFN/LNF, Frascati (Roma)
Istituto Nazionale di Fisica Nucleare, Milano
Rome University La Sapienza, Roma
ENEA C.R. Frascati, Frascati (Roma)
In the frame of the SPARC-X project, the energy of the Photo-Injector SPARC, in operation at INFN-LNF, will be upgraded from 180 to 250 MeV by replacing a low gradient S-band traveling wave accelerating section with two C-band units, designed and developed at LNF. The new system will consist of a 50 MW klystron, supplied by a pulsed modulator, to feed the high gradient C-band structures through a RF pulse compressor. This paper deals with the design of the full system, the C-band R&D activity and study of the related beam dynamics.