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accelerating-gradient

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MOP023 The Accelerating Structure for a 500 GeV CLIC linac, luminosity, wakefield, damping 100
 
  • A. Grudiev, D. Schulte
    CERN, Geneva
 
 

The rf design of an accelerating structure for the 500 GeV CLIC main linac is presented. The design takes into account both aperture and HOM damping requirements coming from beam dynamics as well as the limitations related to rf breakdown and pulsed surface heating. In addition, the constraints related to the compatibility with 3 TeV CLIC have been taken into account. The structure is designed to provide 80 MV/m averaged accelerating gradient at 12 GHz with an rf-to-beam efficiency as high as 39.8 %.

 
TH101 Raising the Bar on Superconducting Cavity Processing, and Performance cavity, laser, SRF, niobium 708
 
  • Z.A. Conway
    CLASSE, Ithaca, New York
 
 

This talk will give an overview of recent results on the highest gradient SRF cavities, including new, improved surface treatments and cavity repair. Significant recent progress has been made in understanding gradient limiting effects, and how to cure them. Many of these results will be reviewed here.

 

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THP036 Updates on Sc Cavity Inspection cavity, niobium, cryogenics, survey 836
 
  • H. Tongu, M. Ichikawa, Y. Iwashita
    Kyoto ICR, Uji, Kyoto
  • H. Hayano, K. Watanabe, Y. Yamamoto
    KEK, Ibaraki
 
 

Optical inspections on superconducting cavities seem to become familiar to those who are involved in the cavity fabrications. Further improvements on the Kyoto Camera have been carried out these years together with further investigation technique developments, such as high density T-map or eddy current scan. Improvements on Kyoto Camera includes change of EL sheets to LEDs, which raised the brightness 10 times and the lifetime very long as known well. The resolution was also increased. The high density T-map will help to locate a hot spot during the vertical tests and the eddy current scan will be useful for screening of bare Nb sheets with possible defects. These progresses will be reported.

 
FR105 Study of Basic Breakdown Phenomena in High Gradient Vacuum Structures cavity, vacuum, collider, electron 1043
 
  • V.A. Dolgashev
    SLAC, Menlo Park, California
 
 

We present the results of R&D aimed at exploring the basic physics of RF breakdown phenomena in high vacuum structures. We performed an extensive experimental survey of materials for RF magnetic field induced metal fatigue. To do this, we designed a cavity operating at a TE01m-like mode which focuses RF magnetic field on the flat sample surface. We tested more than 20 samples of materials including single crystal copper, copper alloys, and refractory metals. With these results in hand, we constructed standing wave cavities of different geometries and materials to conduct RF-breakdown experiments. To study a broad range of materials and surfaces, we explored different structure-joining techniques, including those which allow us to avoid high temperature brazing. Using structures of different geometries, we examined the effect of the mixture of surface electric and magnetic fields on breakdown behavior. To study this effect further we designed a structure in which we can adjust the mixture of fields using two independent RF sources.

 

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