“…It is worth mentioning that the multi-THz frequency content predicted in Figs 3b and 4b reflects typical spectral measurements collected during TeraFERMI operation, see for example Supplementary Information and Fig. 3 in 44 . Figure 3 ( a ) Simulated electron bunch current profiles at the Al target for two optics settings of the dump line (OS1-red and OS2-green).…”
Section: Theoretical and Experimental Resultssupporting
confidence: 54%
“…1 . Since the electron beam manipulation for CTR emission occurs after lasing, the scheme allows the TeraFERMI photon beamline 43 , 44 to run in parasitic mode to the FEL. The THz pulse is self-synchronized to the FEL emission thus opening, in principle, a wide range of scientific applications in pump-probe configurations.…”
We demonstrate that emission of coherent transition radiation by a ∼1 GeV energy-electron beam passing through an Al foil is enhanced in intensity and extended in frequency spectral range, by the energy correlation established along the beam by coherent synchrotron radiation wakefield, in the presence of a proper electron optics in the beam delivery system. Analytical and numerical models, based on experimental electron beam parameters collected at the FERMI free electron laser (FEL), predict transition radiation with two intensity peaks at ∼0.3 THz and ∼1.5 THz, and extending up to 8.5 THz with intensity above 20 dB w.r.t. the main peak. Up to 80-µJ pulse energy integrated over the full bandwidth is expected at the source, and in agreement with experimental pulse energy measurements. By virtue of its implementation in an FEL beam dump line, this work promises dissemination of user-oriented multi-THz beamlines parasitic and self-synchronized to EUV and x-ray FELs.
“…It is worth mentioning that the multi-THz frequency content predicted in Figs 3b and 4b reflects typical spectral measurements collected during TeraFERMI operation, see for example Supplementary Information and Fig. 3 in 44 . Figure 3 ( a ) Simulated electron bunch current profiles at the Al target for two optics settings of the dump line (OS1-red and OS2-green).…”
Section: Theoretical and Experimental Resultssupporting
confidence: 54%
“…1 . Since the electron beam manipulation for CTR emission occurs after lasing, the scheme allows the TeraFERMI photon beamline 43 , 44 to run in parasitic mode to the FEL. The THz pulse is self-synchronized to the FEL emission thus opening, in principle, a wide range of scientific applications in pump-probe configurations.…”
We demonstrate that emission of coherent transition radiation by a ∼1 GeV energy-electron beam passing through an Al foil is enhanced in intensity and extended in frequency spectral range, by the energy correlation established along the beam by coherent synchrotron radiation wakefield, in the presence of a proper electron optics in the beam delivery system. Analytical and numerical models, based on experimental electron beam parameters collected at the FERMI free electron laser (FEL), predict transition radiation with two intensity peaks at ∼0.3 THz and ∼1.5 THz, and extending up to 8.5 THz with intensity above 20 dB w.r.t. the main peak. Up to 80-µJ pulse energy integrated over the full bandwidth is expected at the source, and in agreement with experimental pulse energy measurements. By virtue of its implementation in an FEL beam dump line, this work promises dissemination of user-oriented multi-THz beamlines parasitic and self-synchronized to EUV and x-ray FELs.
“…The overall TeraFERMI performances, were are already summarized in Reference [17]. During standard user operation conditions the beamline produces THz pulses whose energy ranges from 15 to 60 µJ per pulse, with a bunch charge of ∼700 pC and a bunch length of about 1 ps, as measured at the end of the LINAC.…”
Section: Beamline Performancementioning
confidence: 99%
“…The optical spectrum, as measured by a Michelson interferometer, extends up to 4 THz. However, upon optimization of the electron beam compression specific for TeraFERMI, energies at source up to 100 µJ and a spectral extent up to 12 THz were measured [17]. Two characteristic spectra illustrating the performances under standard and THz beamline-dedicated machine conditions are shown in Figure 3.…”
TeraFERMI is the THz beamline at the FERMI free-electron-laser facility in Trieste (Italy). It uses superradiant Coherent Transition Radiation emission to produce THz pulses of 10 to 100 μ J intensity over a spectral range which can extend up to 12 THz. TeraFERMI can be used to perform non-linear, fluence-dependent THz spectroscopy and THz-pump/IR-probe measurements. We describe in this paper the optical set-up based on electro-optic-sampling, which is presently in use in our facility and discuss the properties of a representative THz electric field profile measured from our source. The measured electric field profile can be understood as the superimposed emission from two electron bunches of different length, as predicted by electron beam dynamics simulations.
“…The first exploits current effects, i.e., the fact that a time-varying charge current can act as a radiation source [27]. This basic concept holds for antennas [28][29][30][31][32][33], which are widely used in conjunction with non-amplified pulsed lasers to perform terahertz time-domain spectroscopy, and for particle accelerators, where relativistic electron beams are deflected by magnets and thereby emit radiation of tunable wavelength [34][35][36] that can cover the THz range [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. While accelerators can cover a large frequency range, these complex machines are often optimized for a certain range because optical elements have limited bandwidths [53].…”
Water is the most prominent solvent. The unique properties of water are rooted in the dynamical hydrogen-bonded network. While TeraHertz (THz) radiation can probe directly the collective molecular network, several open issues remain about the interpretation of these highly anharmonic, coupled bands. In order to address this problem, we need intense THz radiation able to drive the liquid into the nonlinear response regime. Firstly, in this study, we summarize the available brilliant THz sources and compare their emission properties. Secondly, we characterize the THz emission by Gallium Phosphide (GaP), 2–{3–(4–hydroxystyryl)–5,5–dimethylcyclohex–2–enylidene}malononitrile (OH1), and 4–N,N–dimethylamino–4′–N′–methyl–stilbazolium 2,4,6–trimethylbenzenesulfonate (DSTMS) crystals pumped by an amplified near-infrared (NIR) laser with tunable wavelength. We found that both OH1 as well as DSTMS could convert NIR laser radiation between 1200 and 2500 nm into THz radiation with high efficiency (> 2 × 10−4), resulting in THz peak fields exceeding 0.1 MV/cm for modest pump excitation (~ mJ/cm2). DSTMS emits the broadest spectrum, covering the entire bandwidth of our detector from ca. 0.5 to ~7 THz, also at a laser wavelength of 2100 nm. Future improvements will require handling the photothermal damage of these delicate organic crystals, and increasing the THz frequency.
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