Author: Yeremian, A.D.
Paper Title Page
MOPC071 Status of High Power Tests of Normal Conducting Short Standing Wave Structures* 241
 
  • V.A. Dolgashev, Z. Li, S.G. Tantawi, A.D. Yeremian
    SLAC, Menlo Park, California, USA
  • Y. Higashi
    KEK, Ibaraki, Japan
  • B. Spataro
    INFN/LNF, Frascati (Roma), Italy
 
  Funding: Work Supported by Doe Contract No. DE-AC02-76SF00515
We report results of continuing high power tests of short standing wave structures. These tests are part of an experimental and theoretical study of basic physics of rf breakdown in 11.4 GHz, normal conducting structures. The goal of this study is to determine the accelerating gradient capability of normal conducting rf powered particle accelerators. We have tested structures of different geometries, cell joining techniques, and materials. We found that the breakdown rate dependence on peak magnetic fields is stronger than on peak surface electric fields for cylindrically symmetric structures powered via a TM01 mode launcher. We report test results for structures powered by side-coupled rectangular waveguides. We found that increased rf magnetic field due to the side-coupling increases the breakdown rate as compared to the same accelerating gradient in cylindrically symmetric structures.
 
 
MOPC073 A Dual-mode Accelerating Cavity to Test RF Breakdown Dependence on RF Magnetic Fields 247
 
  • A.D. Yeremian, V.A. Dolgashev, J. Neilson, S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  Funding: * Work Supported by Doe Contract No. DE-AC02-76SF00515
RF Breakdown experiments on short accelerating structures at SLAC have shown that increased rf magnetic fields increase the probability of rf breakdowns. Moreover, the breakdown rate is highly correlated with the peak pulse-heating in soft-copper single-cell standing-wave structures of disk-loaded waveguide type. In these geometries the rf electric and magnetic fields are highly correlated. To separate effects of rf magnetic and electric fields on the rf breakdown rate, we have designed an X-band cavity with a geometry as close to that of a standing-wave accelerator cell as practically possible. This cavity supports two modes: an accelerating TM mode and a TE mode with no-surface-electric field but with a strong magnetic field. The cavity will be constructed and tested at the Accelerator Structure Test Area (ASTA) at SLAC.