New Helmholtz-Russia Joint Research Group at PITZ approved
Best injectors for modern X-ray sources: recently approved by the Helmholtz Association, the Helmholtz-Russia Joint Research Group headed by Mikhail Krasilnikov from DESY and Efim Khazanov from Institute for Applied Physics in Nizhny Novgorodand will optimise the generation of high charge electron bunches at PITZ (Photo Injector Test facility in Zeuthen), with the aim to further improve the properties of free-electron lasers. The Helmholtz Association will fund the group over a period of three years with a total of 390 000 euros, another 3.6 million rouble coming from Russia. The German-Russian research cooperation continues a long-term project funded by the German ministry of research in 2010, with the intention to develop the ideal electron sources for the research light sources of the future at DESY.
With their bright and ultra-short X-ray flashes, free-electron lasers like FLASH or the European XFEL currently under construction promise to provide ideal possibilities for a number of research disciplines. However, the electron bunches injected into the superconducting accelerators of these facilities are an essential criterion for optimal X-ray laser flashes. They must consist of a large number of electrons to be guided into the accelerator in the highest possible order and extremely bundled. These bunches are produced with the help of a so-called photo injector in which an intensive laser flash releases a dense electron cloud from a photo cathode. In 1999, construction of the PITZ facility was started with the purpose to test this important X-ray laser component; moreover, many technologies and methods for photo injectors were improved.
Already now, the scientists have demonstrated that with a photocathode laser system developed by the Max Born Institute they can provide both the world’s best emittance – a measure for parallelism and bundling of the flying electrons – and a very high stability. However, computer-generated simulations promise additional improvements of the electron bunch properties when the releasing laser pulses do not have a uniform intensity over the whole pulse duration (a so-called beer can profile) but have an egg-shaped profile in space and time. The simulations suggest an emittance improvement of up to 30 per cent. Based on the previous developments, the new project will test at PITZ if this further improvement of free-electron lasers is possible. If this technology proves to be successful, it would allow higher tolerances in the operating parameters of free-electron lasers, thus increasing the flexibility of these FEL’s. At the same time, the scientists want to test the possibility of producing ultra-short electron bunches with this injector technology that would allow even shorter X-ray laser flashes.