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Higo, T.

Paper Title Page
TUP95 Evaluation of Magnetic Field Enhancement Along a Boundary 501
  • Y. Iwashita
    Kyoto ICR, Kyoto
  • T. Higo
    KEK, Ibaraki
  Generally, a cavity has convex corners on its inner surface, where the surface field becomes higher than the average accelerating gradient. This effect has been paid attention not to exceed a criterion only on surfaces that have high electric field gradient. A high magnetic field area, however, sometimes seems harmful on a stable operation too. Such enhancement factors are evaluated in a 2D model to show a feasible crossing angle limit on a convex angle of two surfaces.  
THP67 Traveling Wave and Standing Wave Single Cell High Gradient Tests 766
  • V.A. Dolgashev
    SLAC/ARDB, Menlo Park, California
  • Y. Higashi, T. Higo
    KEK, Ibaraki
  • C.D. Nantista, S.G. Tantawi
    SLAC/ARDA, Menlo Park, California
  Accelerating gradient is one of the crucial parameters affecting design, construction and cost of next-generation linear accelerators. Operating accelerating gradient in normal conducting accelerating structures is limited by rf breakdown. In this paper we describe an experimental setup for study of these limits for 11.4 GHz traveling-wave and standing-wave accelerating structures. The setup uses matched mode converters that launch the circular TM01 mode and short test structures. The test structures are designed so that the electromagnetic fields in one cell mimic the fields in prototype structures for the Next Linear Collider. Fields elsewhere in the test structures and in the mode converters are significantly lower then in this single cell. This setup allows economic testing of different cell geometries, cell materials and preparation techniques with short turn around time. In this paper we present design considerations and initial experimental data.  
THP33 Progress toward NLC/GLC Prototype Accelerator Structures 675
  • J. Wang, G. Bowden, V.A. Dolgashev, R.M. Jones, J. Lewandowski, C.D. Nantista, S.G. Tantawi
    SLAC/ARDA, Menlo Park, California
  • C. Adolphsen, D.L. Burke, J.Q. Chan, J. Cornuelle, S. Döbert
    SLAC/NLC, Menlo Park, California
  • T. Arkan, C. Boffo, H. Carter, N. Khabiboulline
    FNAL, Batavia, Illinois
  • N. Baboi
    DESY, Hamburg
  • D. Finley, I. Gonin, S. Mishra, G. Romanov, N. Solyak
    Fermilab, Batavia, Illinois
  • Y. Higashi, T. Higo, T. Kumi, Y. Morozumi, N. Toge, K. Ueno
    KEK, Ibaraki
  • Z. Li, R. Miller, C. Pearson, R.D. Ruth, P.B. Wilson, L. Xiao
    SLAC, Menlo Park, California
  The accelerator structure groups for NLC (Next Linear Collider) and GLC (Global Linear Colliders) have successfully collaborated on the research and development of a major series of advanced accelerator structures based on room-temperature technology at X-band frequency. The progress in design, simulation, microwave measurement and high gradient tests are summarized in this paper. The recent effort in design and fabrication of the accelerator structure prototype for the main linac is presented in detail including HOM (High Order Mode) suppression and couplers, fundamental mode couplers, optimized accelerator cavities as well as plans for future structures. We emphasize techniques to reduce the field on the surface of the copper structures (in order to achieve high accelerating gradients), limit the dipole wakefields (to relax alignment tolerance and prevent a beam break up instability) and improve shunt impedance (to reduce the RF power required).