ABSTRACT
A superconducting radio frequency (SRF) photoelectron injector is currently under construction by a collaboration of BESSY, DESY, FZD, and MBI. The project aims at the design and setup of a continuous-wave SRF injector including a diagnostics beamline for the ELBE free electron laser (FEL) and to address R&D issues on low emittance injectors for future light sources such as the BESSY FEL. Of critical importance for the injector performance is the control of the electron beam parameters. For this reason a compact diagnostics beamline is under development, serving a multitude of operation settings. In this paper the layout and the rationale of the diagnostics beamline are described. Furthermore detailed information on specific components is given, together with results from laboratory tests and data taking.
ABSTRACT
This paper deals with the pulse-shaping properties of birefringent filters that feature an optical layout similar to a Solc fan filter. A simple computational model is given that explains the pulse-shaping process in the fan filter in two steps: First, the input pulse is split into several mutually delayed replicas due to the birefringence of the crystals. Second, these replicas interfere at the output polarizer of the filter and form the shaped output pulse. Fine-tuning of the phases of the replicas of the input pulse is permitted by tuning the temperature of the crystals. A birefringent pulse shaper containing ten birefringent crystals was investigated experimentally. The shape of the output pulses was measured by means of a special cross-correlation technique. Although a variety of pulse shapes can be generated with the described filter, it is particularly well suited for generation of flattop pulses featuring a 20-ps-long plateau and rising and falling edges shorter than 2 ps.
Subject(s)
Computer-Aided Design , Fiber Optic Technology/instrumentation , Filtration/instrumentation , Lasers , Models, Theoretical , Signal Processing, Computer-Assisted/instrumentation , Birefringence , Computer Simulation , Equipment Design , Equipment Failure AnalysisABSTRACT
Compensation of thermally induced birefringence directed toward compensation of depolarization and bifocusing in laser rods is treated with simple beam transfer matrices. When we apply a 90-deg polarization-rotating element to a resonator, the radial and the tangential eigensolutions of the resonator change significantly. The effect of this alteration on the resonator's stability is investigated in detail. The outcome is used to design a single- and double-rod resonator resulting in 53 W with an M2 approximately 1.5 and 182 W of output power with an M2 approximately 1.2, respectively.
