Radboud University, Nijmegen
RI Research Instruments GmbH, Bergisch Gladbach
FZD, Dresden
FOM Rijnhuizen, Nieuwegein
The Radboud University in Nijmegen received funding to realize a narrow-band THz laser system and a 45 T hybrid magnet system. Based on results of predesign studies [1], all review committees agreed to continue the project and enter the realization phase. In this paper we present the technical solutions for realization of the main system components. We present the details of the RI Research Instruments GmbH (a former ACCEL Instruments GmbH activity) LINAC system. Operation of the full system (including the electron source) at 3 GHz is desirable and deemed feasible after first experimental studies. As the Nijmegen FEL will operate at wavelength up to 1.5 mm, the cavity will be fully waveguided, complicating the incorporation of an intra-cavity Fox-Smith interferometer required to induce coherence between micropulses and a Michelson interferometer as most ideal outcoupler. The optical distribution system comprises 150 m of vacuum tubing with 25 cm effective diameter (planar and refocusing) mirrors. A robust yet cost efficient realization taking boundary conditions on optical beam parameters at diagnostics station and user stations into account is foreseen.
[1] Design of the Nijmegen high-resolution THz-FEL, R.T. Jongma, et al. Proc. FEL-08.
FZD, Dresden
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Elektronen-Speicherring BESSY II, Berlin
MBI, Berlin
More and more electron accelerator projects for FELs, ERLs or 4th generation light sources require “super” electron beam with high brightness, low emittance, and high average current. Under this background, much attention is paid on the research and development of new electron sources. Superconducting RF photoinjector was designed within a collaboration of BESSY, DESY, FZD, and MBI to improve the beam quality for ELBE IR-FEL users, and at the same time to test this kind of promising injector concept. The main design parameters of this gun are the final electron energy of 9.5 MeV, 1 mA average current, and transverse normalized emittances (rms) of 1 mm mrad at 77 pC and 2.5 mm mrad at 1 nC bunch charge. In this paper the results of the RF and beam parameter measurements with Cs2Te photo cathodes will be presented, and the experience for the gun running gained at the first experiments will be concluded, including the life time and compatibility of the normal conducting photocathode in SC cavity, the coupling of high average power into the gun, and the excitation of higher-order modes in the cavity.
