Speaker
Description
The FHI Free-Electron Laser (FHI FEL) provides intense, pulsed mid-infrared (MIR) radiation continuously tunable from <3 µm to >50 µm. Since user operation started in 2013, the FHI FEL has enabled in-house user groups and their collaborators to run experiments in diverse fields ranging from spectroscopy of clusters, nanoparticles, and bio-molecules in the gas phase to nonlinear solid-state spectroscopy and surface science. This has resulted in some 85 peer-reviewed publications so far. A 2-color upgrade of the FHI FEL was funded by the Max Planck Society in 2018. Installation of the upgrade has been completed; commissioning is scheduled for fall of 2022.
The FHI FEL Upgrade essentially includes the addition of a second short-Rayleigh-range undulator FEL beamline as outlined in Fig. 1. The second FEL branch will permit lasing in the far-infrared (FIR) regime from <5 µm to >160 µm. In addition, a 500 MHz kicker cavity has been inserted downstream of the electron accelerator. It is powered by a 65-kW, 500-MHz solid-state amplifier and operates in a dipole mode using the strong electric field between two vanes to deflect electron bunches up to 50 MeV energy alternatingly left and right by an angle of ±2°. The kicker cavity makes simultaneous operation of both FEL beamlines possible by deflecting every second electron bunch of the 1 GHz bunch train from the accelerator to the MIR branch and every other second bunch to the FIR branch. In this 2-color mode both FEL’s run in parallel each generating infrared pulses at independently tunable wavelengths each at 500 MHz repetition rate. In addition, 2-color operation at reduced repetition rates (e.g. 55.5 MHz of both MIR and FIR pulses), as needed for some applications, will also be available. Furthermore, two additional small dipole magnets upfront and behind the kicker cavity permit conventional single-color operation of either the MIR or the FIR FEL when the 500 MHz field is off.
$\rm \Tiny Figure\ 1\!: Layout\ of\ the\ FHI\ FEL\ 2-color\ upgrade.\ The\ kicker\ cavity\ as\ well\ as\ the\ undulator,\ optical\ cavity,\\ \Tiny and\ electron\ beamline\ of\ the\ new\ FIR\ branch\ have\ been\ installed.\ Commissioning\ is\ planned\ for\ fall\ of\ 2022.$
*Consultants to the Fritz Haber Institute
| Abstract Number (department-wise) | MP 22 |
|---|---|
| Department | MP (Meijer) |
