DESY, Hamburg
With bright electron beams the full length of gap-tunable X-ray FEL undulators can be efficiently used to generate multiple x-ray beams with different independent wavelengths for simultaneous multi-user operation. We propose a betatron switcher and show that one only needs to install a compact fast kicker in front of an undulator without any modifications of the undulator itself. Different groups of bunches get different angular kicks, and for every group a kick is compensated statically (by corrections coils or moving quadrupoles) in a part of the undulator, tuned to the wavelength designated to the given group. As a generalization of the method of the betatron switcher, we briefly describe a scheme for pump-probe experiments.
DESY Zeuthen, Zeuthen
ThEP Center, Commission on Higher Education, Bangkok
Chiang Mai University, Chiang Mai
The Photo-Injector Test Facility at DESY, Zeuthen site (PITZ) aims to optimize high brightness electron sources for linac-based FELs. Since the performance of an FEL strongly depends on the transverse electron beam emittance, the electron source is studied in details at PITZ by measuring the emittance with the help of the Emittance Measurement Systems (EMSYs). The EMSY employs the slit scan technique which is optimized for 1nC bunch charge and, therefore, it might not be an optimal choice for low charge bunches. To extend the ability of the facility for transverse phase space measurements, a module for phase-space tomography diagnostics and its matching section are installed in 2010. The basic components of the module are four screens separated by FODO cells. It is designed for operation with high charge and low energy beams*. This work studies the performance of the tomography module when it is operated with low charge beams. The influence of different beam parameters is evaluated according to the requirement to match the envelope to the optics of the FODO lattice. Simulation results and phase space reconstructions are presented.
G. Asova et al., ‘Design considerations for phase space tomography diagnostics at the PITZ facility', proceedings of DIPAC 2007, Mestre, Italy.
ELETTRA, Basovizza
The optics design of the first bunch compressor area in the FERMI@elettra linac is presented. Several constraints on the Twiss parameters are set by the preservation of beam quality in the first magnetic compressor, the optimization of diagnostics performance, the collimation process and the beam matching to the downstream lattice. A compact multi-purpose arrangement of magnetic and diagnostic elements is presented that, in principle, satisfies several different needs over a total length of 14m.
DESY Zeuthen, Zeuthen
DESY, Hamburg
UCLA, Los Angeles, California
HZB, Berlin
The major objectives of the Photo-Injector Test Facility at DESY in Zeuthen, PITZ, are research and development of high brightness electron sources suitable to drive FELs like FLASH and the European XFEL. In the 2008/2009 run period the facility has been operated with a new photo-cathode laser system and a dry-ice cleaned RF gun cavity. Characterization of the transverse phase space of the electron source has been performed in details using a single slit scan technique with a dedicated Emittance Measurement System. In preparation for the forthcoming run, a number of quadrupole magnets have been installed and tomography reconstruction with data from quadrupole scans with two magnets has been carried out in semi-parallel manner to the slit scans. This contribution summarizes the experience from the phase-space tomography reconstruction with nominal beam conditions. Advantages and drawbacks of the measurement procedure and the analysis are superimposed and results are compared to ones obtained with the slit scans.
ELETTRA, Basovizza
LBNL, Berkeley, California
Simulations of the microbunching instability through the FERMI@elettra lattice have been carried out with elegant particle tracking code. This paper focuses on the emittance growth induced by the microbunching instability in the high energy transfer line that guides the electron beam from the linac to the undulator chain. The perturbation to the transverse emittance induced by coherent synchrotron radiation and longitudinal space charge as function of the R56 transport matrix element in the transfer line have been investigated separately and in the presence of their mutual interaction. Simulation results show that the betatron phase mismatch may have a detrimental impact on the final beam emittance.
KYMA, Trieste
ELETTRA, Basovizza
Euromisure srl, Pieve S. Giacomo (CREMONA)
During 2009 and the first months of 2010, Kyma Srl, the spin-off company set-up by Sincrotrone Trieste, designed and realized all the insertion devices for the undulator chain at the FERMI@Elettra free-electron laser. The insertion devices manufactured and characterized so far are the following: The Laser Heater Undulator, a short, linearly polarized device, already installed in the FERMI linac. The Modulator, a 3.2 m long, linearly polarized undulator. The Radiator, comprising of six APPLE-II variable polarization undulators, each 2.4 m long. All the above devices have been characterized, both from the mechanical and the magnetic point of view. The measured parameters are in good agreement with the design values. This paper presents the most relevant results of the magnetic measurements carried out on all the above undulators, and describes the characteristics and the performance of the dedicated equipment set-up and used for this measurements.
MSL, Stockholm
DESY, Hamburg
European XFEL GmbH, Hamburg
The Manne Siegbahn Laboratory at Stockholm University is currently involved in two separate projects at the European XFEL. The first concerns the fiducialization and characterization of the quadrupole magnets in the undulator sections. A recently upgraded rotating coil system measures the magnetic centre stability during magnet excitation, magnet gradient and field error components. In connection, a coordinate measuring machine is used to fiducialize the quadrupole magnetic centre to better than 0.050 mm. The second project concerns high precision measurements of the undulator temperature. The SASE radiation intensity depends strongly on the undulator period and the magnetic field strength, which are both sensitive to temperature. Instead of keeping the temperature within 0.1 degrees along the undulator tunnel, a temperature compensation scheme can be applied. Here, a change in temperature initiates adjustment of the undulator gap to compensate for changes in magnetic field. A system for undulator segment temperature measurement, with resolution of 0.03 degrees, necessary for the compensation scheme, is presented together with a brief overview of the upgraded rotating coil system.