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microtron

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MOPP049 Injection System for Microtron-Based Terahertz FEL cathode, electron, fel, injection 164
 
  • G.M. Kazakevich
    Fermilab, Batavia, Illinois
  • Y.U. Jeong, B.C. Lee, S.-H. Park
    KAERI, Daejon
  • G.I. Kuznetsov
    BINP SB RAS, Novosibirsk
  • V. M. Pavlov
    Strathclyde University, Glasgow
  
 

Funding: Budker Institute of Nuclear Physics RAS, Academician Lavrentyev 11, Novosibirsk, 630090, Russia; Laboratory for Quantum Optics, Korea Atomic Energy Research Institute, P. O. Box 105, Yusong, Taejon, 305-600, South Korea.

A reliable injection system of the widely tunable microtron-based terahertz Free Electron Laser (FEL) has been developed and during last few years provides stable operation of the FEL for users. The system is based on the long-life thermionic cathode assembly using 2.5 mm-in diameter monocrystalline LaB6 emitter, heated by the tungsten cylindrical filament with the power consumption less than 50 W. The cathode emits the macro-pulse current in the range of 1-1.4 A providing operation of the terahertz FEL during more than 1000 h. The cathode assembly is installed on the cover of the I-type microtron accelerating cavity in location providing an efficient injection for the acceleration with variable number of orbits. This variation widely changes the energy of the electron beam and allows on-the-fly retuning of the FEL in the range of 1-3 THz. Pulse-signal system stabilizing the emission current prevents randomized break-downs in the accelerating cavity and decreases macro-pulse power fluctuations of the FEL radiation. The fluctuations were measured to be less than 10% during long-time operation.

   
    
TUOC004 Peak Fields of Nb3Sn Superconducting Undulators and a Scaling Law undulator, synchrotron, electron, storage-ring 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.