HF-6 is located in our radiation-shielding "bunker" and dedicated to the generation of ultrashort-pulsed (few-fs to sub-fs) moderate-energy (1-100MeV) electron beams with low-emittance and medium charge (1-10-pc and beyond) by means of self-injection in laser wakefield acceleration in the broken-wave (bubble) regime in gas jets and externally controlled (shock-front) injection. The beamline is being seeded with LWS-20. It currently consists of two chambers accommodating optical components for tight as well as loose focusing, the target assembly, plasma diagnostics and for characterizing the generated electron beam. At present, few-fs electron bunches are generated in a several-100-µm thick supersonic helium gas jet and produce mono-energetic, background-free electron beams in the 10-100 MeV energy range, carrying 1-10 pC charge/bunch and exhibiting a divergence of 5-10 mrad. The spectral characterization is performed with permanent-magnet spectrometers optimized for the 1-20 MeV and 2-500 MeV ranges. The transverse profile and the beam pointing are determined by scintillating screens. The charge is measured by an integrating current transformer and by absolutely calibrated scintillating screens. A probe beam is implemented for shadowgraphy and interferometric plasma density characterization. The beamline will be extended with further assemblies for temporal characterization and manipulation of the electron bunch via the inverse free-electron laser mechanism. Once available and fully characterized, the few-fs/sub-fs relativistic electron bunches will be used for time-resolved electron diffraction and brilliant X-ray pulse generation. The simple setup to measure the electron beam is also transverse emittance of the included in the setup.

contact: L.Veisz