First experimental results of the Betatron project at ELI Beamlines

In January/February 2016, a two-phase experiment was performed at the Ti-sapphire laboratory at PALS, Prague. During the first part, which will be presented by Karel Boháček (RP2), a stable source of laser wakefield accelerated (LWFA) electrons was built using a new approach employing compressed air gas jet as a target. The betatron radiation in the keV range was subsequently produced by the relativistic electrons. This x-ray source will be a crucial tool in several applications at ELI, such as phase contrast imaging and X-ray absorption spectroscopy for various types of materials and samples. In the second part, presented by Michal Šmíd (RP5), a slight modification of the setup allowed converting the betatron into a low-energy (~1 MeV) electron accelerator employing the novel downramp LWFA scheme. This range of electrons will be used as a backlighter for electron diffraction and scattering for solid density samples and warm dense matter at E3. During this experiment, the first electron radiography of metalic samples was demonstrated. Both experiments were succesful and provided the first solid steps towards completing the betatron project, which will be one of the important secondary sources at ELI Beamlines.