NOVEL SCHEMES FOR THE NARROW BAND SPARC THZ SOURCE USING A COMB LIKE E-BEAM

The development of radiation sources in the THz spectral region has become more and more interesting because of the peculiar characteristics of this radiation: it is non ionizing, it penetrates dielectrics, it is highly absorbed by polar liquids, highly reflected by metals and reveals specific "fingerprint" absorption spectra arising from fundamentals physical processes. The THz source at SPARC is an accelerator based source for research investigations (e.g. material science, biology fields). By means of e-beam manipulation technique, a longitudinal modulated beam, the so-called comb beam, can be produced at SPARC. In terms of THz sources, such e-beam distribution allows to produce high intensitiy narrow band THz radiation, whose spectrum strongly depends on the charge distribution inside the e-beam. In this paper different linac schemes are compared. In particular, spectra obtained using the comb beam compression through velocity bunching including a IV harmonic RF section is showed.