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RF-structure

 
Paper Title Other Keywords Page
MOP70 A Pass Band Performance Simulation Code of Coupled Cavities simulation, linac, coupling, beam-loading 183
 
  • X. Tao, D. Tong
    TSINGHUA, Beijing
  A simulation code of accelerating cavities named PPSC is developed by the solutions of the microwave equivalent circuit equations. PPSC can give the pass band performance of periodic or non-periodic accelerating structures, such as the dispersion frequency and the reflection factor of the cavity, the field distribution of each mode and so on. The natural parameters of the structure, such as the number of the cavities, the resonant frequencies and Q-factors of each cavity, the coupling factor between two cavities, and the locations of the couplers, can be changed easily to see the different results of the simulation. The code is written based on MS Visual Basic under MS windows. With these, a user-friendly interface is made. Some simple examples was simulated and gave reliable results.  
 
TU201 The KEK C-Band RF System for a Linear Collider linac, klystron, collider, linear-collider 256
 
  • H. Matsumoto, S. Takeda, S.S. Win, M. Yoshida
    KEK, Ibaraki
  • H. Baba, T. Shintake
    RIKEN Spring-8 Harima, Hyogo
  • J-O. Oh
    PAL, Pohang
  The C-band (5712 MHz) main linac has been developed just motivated by the urgent and essential physics program at the e+e- linear collider. In total ~8000 accelerating structures and ~4000 klystrons with modulators are needed for 500 GeV C.M. energy. Therefore these units have to meet strict requirements for: high reliability, simplicity, easy operation, reasonable power efficiency and low cost. This list provides a guiding principle and the boundary conditions for our design work. We have already developed the conventional and PPM type 50 MW class C-band klystrons, modulators, and HOM-free accelerator structures. The first high power an rf compressor cavity made of a low thermal expansion material was designed to provide stable operation even with a very high Q of 200 k, it was successfully operated an output rf power of 135 MW at KEK. The C-band linac rf-system will be used for the SASE-FEL project at SPring-8, but it will also serve to verify the design and components, which can eventually be deployed for the main linac rf system in a future linear collider.  
Transparencies
 
TUP84 Spectrographic Approach to Study of RF Conditioning Process in Accelerating RF Structures plasma, vacuum, quadrupole, electron 471
 
  • H. Tomizawa, H. Hanaki, T.  Taniuchi
    JASRI-SPring-8, Hyogo
  • A. Enomoto, Y. Igarashi, S. Yamaguchi
    KEK, Ibaraki
  The acceleration gradient of a linac is limited by rf breakdown in its accelerating structure. We applied an imaging spectrograph system to study the mechanism of rf breakdown phenomena in accelerating rf structures. Excited outgases emit light during rf breakdown, and the type of outgases depend on surface treatments and rinsing methods for their materials. To study rf breakdown, we used 2-m-long accelerating structures and investigated the effects when high-pressure ultrapure water rinsing (HPR) treatment was applied to these rf structures. We performed experiments to study the outgases under rf conditioning with quadruple mass spectroscopy and imaging spectrography. As a result, we could observe instantly increasing signals at mass numbers of 2 (H2), 28 (CO), and 44 (CO2), but not 18 (H2O) just after the rf breakdown. We also conducted spectral imaging for the light emissions from the atoms in a vacuum that are excited by rf breakdown. Without HPR, we observed the atomic lines at 511 nm (Cu I), 622 nm (Cu II), and 711 nm (C I). With HPR, 395 nm (O I), 459 nm (O II), 511 nm (Cu I), 538 nm (C I), 570 nm (Cu I), 578 nm (Cu I), 656 nm (H I), and 740 nm (Cu II) were observed.  
 
THP84 Design of a 300 GHz Broadband TWT Coupler and RF-Structure coupling, simulation, electron, plasma 794
 
  • F.L. Krawczyk, F.E. Sigler
    LANL/LANSCE, Los Alamos, New Mexico
  • B.E. Carlsten, L.M. Earley
    LANL, Los Alamos, New Mexico
  • J.M. Potter
    JP Accelerator Works, Inc., 2245, Los Alamos, NM
  • M.E. Schulze
    GA, Los Alamos
  • E. Smirnova
    MIT/PSFC, Cambridge, Massachusetts
  Recent LANL activities in millimeter wave structures focus on 94 and 300 GHz structures. They aim at power generation from low power (100–2000 W) with a round electron beam (120 kV, 0.1–1.0 A) to high power (2–100 kW) with a sheet beam structure (120 kV, 20 A). Applications cover basic research, radar and secure communications and remote sensing of biological and chemical agents. In this presentation the design and cold-test measurements of a 300 GHz RF-structure with a broadband (>6% bandwidth) power coupler are presented. The design choice of two input/output waveguides, a special coupling region and the structure parameters themselves are presented. As a benchmark also a scaled up version at 10 GHz was designed and measured. These results will also be presented.