| Paper |
Title |
Page |
| TUBX01 |
Impedance and radiation generated by a ceramic chamber with RF shields and TiN coating
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125 |
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- Y. H. Chin, S. Lee, K. Takata, T. Toyama
KEK, Ibaraki
- Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- H. Tsutsui
SHI, Tokyo
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In the RCS (Rapid Cycle Synchrotron) ring of J-PARC, we use ceramic chambers with the interior TiN coating and exterior Cu RF shields in the magnet sections. A new theory has been developed for calculation of impedance in this unusual configuration. When it was applied to a prototype RCS ceramic chamber, the calculation results got good agreement with the measurement results. We also considered the dipole radiation from gaps between Cu shields of the ceramic chamber in the bending magnets. The effects turn out to be rather small thanks to the special configuration of the ceramic chambers. We measured the radiation from a ceramic break with and without RF shields and capacitors in the KEK, PS and found that the RF shields with capacitors considerably suppress the radiation from the ceramic break. We summarize all these studies in this paper.
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| TUBX03 |
Coupling impedance of the J-PARC kicker magnets
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140 |
| |
- T. Toyama, Y. Hashimoto, E. Nakamura, Y. Shirakabe
KEK, Ibaraki
- J. Kamiya, Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
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The single- and twin-wire measurements both for the longitudinal ( ZL ) and transverse impedances ( ZT ) will be discussed for the J-PARC kicker magnets: a lumped circuit kicker and several types of traveling wave kickers. The question if a position shifted single-wire can measure ZT is discussed. The measurement results are compared with the equivalent circuit analysis. The relation between the imaginary part of the impedance and causality will also be discussed.
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| TUBZ01 |
The Beam Diagnostics System for J-PARC Synchrotrons
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128 |
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- N. Hayashi, S. H. Hiroki, K. Satou, R. Toyokawa
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- D. A. Arakawa, Y. Hashimoto, S. Lee, T. Miura, T. Toyama
KEK, Ibaraki
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The beam diagnostics system for J-PARC synchrotrons (RCS and MR) will be presented. The design of the system will be described for high current machines. Some test results will be reported.
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| WEBX02 |
Observation of Emittance Growth at the injection in the KEK PS Main Ring
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250 |
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- S. Igarashi, T. Miura, E. Nakamura, Y. Shimosaki, M. J. Shirakata, K. Takayama, T. Toyama
KEK, Ibaraki
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We have been studying the emittance growth and beam loss mechanism during the injection period of the 12 GeV main ring of the KEK proton synchrotron to achieve higher intensity. The typical beam loss is about 30 % during the injection period of 500 milliseconds for the high intensity operation. Measurement of the transverse beam profiles using flying wires has revealed a characteristic temporal change of the beam profile within a few milliseconds after the injection. Horizontal emittance growth was observed when the horizontal tune was close to the integer. The effect was more enhanced for higher beam intensity and could not be explained with the injection mismatch. A resonance created by the space charge field was the cause of the emittance growth. A multiparticle tracking simulation program, ACCSIM, taking account of space charge effects has successfully reproduced the beam profiles.
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