TUOC :: FEL Technology II: Undulators

Date/Time: 23-Aug-05 :: 15:45—17:30
Chair: J.-S. Oh, PAL, Pohang, Kyungbuk

Paper Title Page
TUOC001 In-Vacuum Undulators 370
 
  • T. Tanaka
    RIKEN Spring-8, Hyogo
  • T. Bizen, D. Iwaki, X. Marechal, T. Seike, R. Tsuru
    JASRI/SPring-8, Hyogo
  • T. Hara, H. Kitamura
    RIKEN Spring-8 Harima, Hyogo
 
 

In-vacuum undulators are now widely used in lots of SR facilities to provide highly-brilliant hard x-rays not only in large-scale facilities such as SPring-8, ESRF and APS, but also in medium-scale facilities with an electron energy up to 3 GeV. In addition, the SCSS (SPring-8 Compact SASE Source) project is going to adopt the in-vacuum undulator not only for reducing the electron energy to achieve angstrom X-ray FEL but also for commissioning and alignment of components in the undulator line that takes advantage of variable vacuum gap (physical aperture for the electron beam). In this talk, overview of technologies required for development of the in-vacuum undulator will be presented together with practical examples. In addition, ongoing R&Ds at SPring-8 (cryogenic undulator, in-situ field measurement system) will be described in brief.

 
   
TUOC002 Undulator Systems and Photon Dignostic Plans for the European XFEL Project 378
 
  • J. Pflueger
    DESY, Hamburg
 
 

The undulator systems for the European XFEL project will produce 0.1nm radiation. Their length will exceed 200m. they will be segmented into 40-50 segments. There will be very demanding requirements on the performance of the undulator segments. The concept for building these systems will be explained in detail. This includes drive systems, magnet structures, control systems, phase shifter and othe components in the intersections as well. An important role plays the photon diagnostic station which is foreseen for each SASE FEL beam line. It can be used for steering the beam through the undulator line, for precision gap tuning of individual undulator segments and for precise phase matching of neighbouring devices. An important role plays the interaction with the undulator control system.

 
   
TUOC003 Magnetic Properties of Undulator Vacuum Chamber Materials for the Linac Coherent Light Source 383
 
  • S.-H. Lee, S. Sasaki, I. Vasserman, D.R. Walters
    ANL, Argonne, Illinois
  • D.E. Kim
    PAL, Pohang, Kyungbuk
 
 

Funding: Work supported by DOE under contract no. W-31-109-Eng-38.

A prototype vacuum chamber is being designed for use in the Linac Coherent Light Source at Stanford Linear Accelerator Center under development at the Advanced Photon Source. The chamber will be fabricated from the austenite stainless steels. In general, the magnetic properties of austenite stainless steels are affected by their compositions, processing methods and physical conditions. Austenite stainless steels are generally regarded as non-magnetic in the annealed condition and not attracted significantly by a magnet. However, cold working or welding will change their magnetic properties. This paper presents measurements use to choose a proper chamber material for LCLS undulator, to examine the fabrication processes, and to investigate the relative magnetic permeabilities of the stainless steels such as 316LN, 20Cb-3, Nitronic 33, Nitronic 40 and 310S. This paper presents the results of fabricating of 3"-long vacuum chambers along with their permeability measurements. In addition, the magnetic field variations with/without vacuum chamber under APS undulator A and numerical studies of magnetic field to the permeability of the flat/cylindrical chambers are presented.

 
   
TUOC004 Peak Fields of Nb3Sn Superconducting Undulators and a Scaling Law 387
 
  • S.H. Kim
    ANL, Argonne, Illinois
 
 

Funding: Work supported by the U.S. Department of Energy under Contract No. W-31-109-ENG-38.

The peak fields on the beam axis and the maximum fields in the conductor of Nb3Sn superconducting undulators (SCUs) were calculated for an undulator period length of 16 mm. Using a simple scaling law for SCUs [1], the peak fields, as well as the conductor maximum fields and the current densities, were calculated for a period range of 8 to 32 mm. The critical current densities of commercially available Nb3Sn superconducting strands were used for the calculations. The achievable peak fields are limited mainly by the flux-jump instabilities at low fields. The possible or feasible peak field will also be compared with that achieved in prototype development of SCUs.

[1] S. H. Kim, Nucl. Instrum. Methods A, accepted for publication.