The OK-5/Duke Storage Ring VUV FEL with Variable Polarization

(TH-2-02) Presenting Author: Nikolai Vinokurov (Invited)

V.N. Litvinenko, S.F. Mikhailov (1); N.A. Vinokurov, N.G. Gavrilov, D.A. Kairan, G.N. Kulipanov, O.A. Shevchenko, T.V. Shaftan, P.D. Vobly (2); Y. Wu (3)  

(1) FEL Laboratory, Department of Physics, Duke University, Durham, NC, USA``; (2) Budker Institute of Nuclear Physics,Novosibirsk, Russia; (3) ALS, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

This talk gives overview of the OK-5/Duke storage ring FEL project which was started in 1998. The 24.2-meter long magnetic system of the OK-5 comprises of four electromagnetic wigglers with controllable polarization and three matching sections between them. Each 2.7-m long matching section has a buncher, a triplet of qudrupoles and a collision point for generation of gamma-ray beams via intracavity Compton backscattering. The lattice of matching sections is rather flexible to provide optimal conditions for variety of operation modes. In this talk we discuss the design and expected performance of the VUV OK-5/Duke storage ring FEL.

Each of four 4-meter long OK-5 wigglers comprised of vertical and horizontal electromagnetic arrays shifted for a quarter of the period. Horizontal and vertical fields are controlled independently to tune both the wavelength and polarization of radiation. Presently all four wigglers are assembled and undergoing magnetic tests. Magnetic measurements show good agreement with simulations of magnetic fieldusing 3D-program Mermaid [1]. We present details of numerical analysis of 3D-magnetic field in the OK-5 wigglers with emphasis on the quality of the field and its influence of the electron beam dynamics. Because of its length and strong non-linear focusing, the OK-5 FEL has a significant impact on the electron beam dynamics. Particle tracking simulation is carried out to study the detailed influence of the OK-5 FEL system. We present the dynamic aperture simulation results for the OK-5 FEL.

The OK-5 FEL is a first distributed optical klystron. In this paper we present calculation of the main parameters of the OK-5 VUV FEL such as its tuning range, gain and lasing power. Based on our calculations for the OK-5 FEL we present the predictions for the OK-5 gamma-ray source. We also briefly discuss the mode in which one of the wigglers is fed tuned on a harmonic of the OK-5 FEL to provide optimal conditions for harmonic generation in VUV and soft-X-ray ranges.

[1] A. Dubrovin, Novosibirsk, Russia