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Title |
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| THP67 |
Traveling Wave and Standing Wave Single Cell High Gradient Tests
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766 |
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- 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
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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.
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| THP33 |
Progress toward NLC/GLC Prototype Accelerator Structures
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675 |
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- 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
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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).
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| THP60 |
High-Power RF Distribution System for the 8-Pack Project
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751 |
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- C.D. Nantista
SLAC/ARDB, Menlo Park, California
- D.P. Atkinson
LLNL, Livermore
- J.Q. Chan
SLAC/NLC, Menlo Park, California
- S.Y. Kazakov
KEK, Ibaraki
- D.C. Schultz
SLAC, Menlo Park, California
- S.G. Tantawi
SLAC/ARDA, Menlo Park, California
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The 8-Pack Project at SLAC is a prototype rf system whose goal is to demonstrate the high-power X-band technology developed in the NLC/GLC program. In its first phase, it has reliably produced a 400 ns rf pulse of over 500 MW using a solid-state modulator, four 11.424 GHz klystrons and a dual-moded SLED-II pulse compressor [1]. In Phase 2, the output power of our system has been delivered into the bunker of the NLCTA (Next Linear Collider Test Accelerator) and divided between several accelerating structures, first four and finally eight, for beam acceleration. We describe here the design, cold-test measurements, and processing of this power distribution system. Due to the high power levels and the need for efficiency, overmoded waveguide and components are used. For power transport, the TE 01 mode is used in 7.44 cm and 4.064 cm diameter circular waveguide. Only near the structures is standard WR90 rectangular waveguide employed. Components used to manipulate the rf power include transitional tapers, mode converters, overmoded bends, fractional directional couplers, and hybrids.
[1] S. Tantawi, et al., “Status of High-Power Tests of the Dual-Mode SLED-II System for an X-Band Linear Collider,” FR202, these proceedings.
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| FR202 |
Status of High-Power Tests of Dual Mode SLED-II System for an X-Band Linear Collider
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852 |
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- S.G. Tantawi
SLAC/ARDA, Menlo Park, California
- V.A. Dolgashev, C.D. Nantista
SLAC/ARDB, Menlo Park, California
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We have produced 400 ns rf pulses of greater than 500 MW at 11.424 GHz with an rf system designed to demonstrate technology capable of powering a TeV scale electron-positron linear collider. Power is produced by four 50 MW X-band klystrons run off a common 400 kV solid-state modulator. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant-line (SLED-II) pulse compression system. Dual-moding of the transmission lines allows power to be directed through a pulse compression path or a bypass path; dual-moding in the pulse compressor allows the delay lines to be about half as long as they otherwise would need to be. We describe the design and performance of various components, including hybrids, directional couplers, power dividers, tapers, mode converters, and loads. These components are mostly overmoded to allow for greater power handling. We also present data on the processing and operation of this system. The power from that system is transported to feed a set accelerator structure. We will present the design and the high power testing data for the overmoded transfer line and the distribution network.
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Transparencies
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