[en] Since 2003, the radiation source ELBE at the Research Centre Dresden-Rossendorf delivers infrared light, X-rays and Bremsstrahlung of high intensity for fundamental research. The experimental proposals are associated with the structure of matter, life sciences as well as environment and safety related topics and come from the institute itself, as well as from in-ternational guests. The design and the technical implementation of the 40 MeV superconducting electron beam linear accelerator are explained with regard to the generation of the different types of secon-dary radiation. The article also highlights beam diagnostics and optimization of the beam quality and availability with respect to the different demands on its main properties (energy, bunch charge, emittance, time structure) and the ongoing installation of facility parts

[en] The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) will operate two InfraRed Free Electron Lasers (IR-FEL) covering the range of 3–250 μm. The facility will consist of an injector fed by a thermionic triode gun with two-stage RF bunch compression, two superconducting accelerating ELBE modules operating at continuous wave (CW) mode and two independent optical resonator systems with different undulator period lengths. The electron beam will also be used to generate Bremsstrahlung radiation. In this study, we present the electron beam transport including beam matching to the undulators and the shaping of the longitudinal phase space using magnetic dispersive sections

[en] Dielectrically lined rectangular waveguides provide the possibility to passively reduce the energy spread of particle beams via the interaction of the beam and its own wakefield. Such a device is commonly referred to as a dechirper, and is currently used as a prototype for perspective studies at the Helmholtz-Zentrum Dresden-Rossendorf. During the beam time in the second half of the year 2016, an 80 cm long structure was inserted into the beam line and tested regarding its dechirping effect on the beam. In this work, we present the geometry of the dechirper and report on the status of the prototype and the first measurements made with it.

[en] Dielectrically lined waveguides are planned to be used as a passive wakefield dechirper for the electron beam at the ELBE facility of the Helmholtz-Zentrum Dresden Rossendorf. In this work we introduce the design of such a passive wakefield dechirper based on the analysis of dielectrically lined rectangular waveguides with a semi-analytical model developed at the University of Rostock. The generality of this model allows for a quick calculation of the wakefields of numerous different beam types via the Green's function method. In this work, we present the dechirped phase-spaces of a variety of beam distributions, as well as the theoretically possible dechirping for the ELBE beam. Furthermore, we present an experimental structure planned at the ELBE facility to verify the calculated dechirping effect.

[en] The continuous wave electron accelerator ELBE is upgraded to generate short and highly charged electron bunches (200 fs duration, up to 1 nC) with an energy of up to 40 MeV. In the last years a prototype of an optical synchronization system using a mode locked fiber laser has been build up which is now in commissioning phase. The stabilized pulse train can be used for new methods of electron bunch diagnostics like bunch arrival time measurement with the resolution down to a few femtoseconds. At ELBE a bunch arrival time monitor (BAM) has been designed and tested at the accelerator. The contribution shows the concept of the femtosecond synchronization system, the design of the BAM and first measurement results.

[en] Highlights: • Eigenmodes of dechirpers with dielectric slabs possess analytical expressions. • The wake function in a rectangular dechirper is computed by an eigenmode expansion. • The wake function has an analytical expression. • The wake function can be effectively computed by a Python-based code. • The computation algorithm is independent of spatial discretisation. In this work, a semi-analytical method for determining wakefields in dielectrically lined rectangular waveguides is presented. This approach is based on a Rayleigh–Ritz method to analytically identify the eigenmodes of the structure, which is currently studied for the application as a so-called ‘wakefield dechirper’. The electric field is subsequently determined through an eigenmode expansion, and the wakefield is calculated from the electric field. By virtue of using an analytic ansatz throughout the wakefield determination, an expression for the Green's function wakefield is found. The semi-analytical method is then benchmarked against simulations using purely numerical approaches. Compared to numerical approaches, the advantages of the presented method are the independence from any need of discretisation, the computational efficiency of the method's presented Python-based implementation and finally the opportunity to calculate a true Green's function wakefield. From this Green's function, the wake potentials of different bunch shapes can be obtained via convolution.

[en] It has been shown recently that relativistic electron bunches can be utilized for the generation of super-radiant coherent THz radiation by one single pass through an undulator, bending magnet, or CDR/CTR screens. However, the high THz fields have all been achieved at large accelerators that allow for high electron beam energies. A crucially important research topic for the next years at the HZDR is therefore to investigate whether an equally fine control over highly charged electron bunch form can be routinely achieved in a low electron beam energy accelerator like ELBE. If successful this development would allow the generation of high field THz fields by linear accelerators at considerably reduced cost. Given stable operation can be provided, TELBE, could also become a world-wide unique research facility for high field THz science. The current status and an outlook on future developments are presented.

[en] After successful tests of a SRF gun with a superconducting half-cell cavity a new SRF photoinjector for cw operation at the ELBE linac is under development. The paper discuss the design of the injector, the technological challenges of different components, the status of manufacturing and the expected parameters