| Paper |
Title |
Page |
| WEPKF080 |
Secondary Electron Yield Measurements from Thin Surface Coatings for NLC Electron Cloud Reduction
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1789 |
| |
- F. Le Pimpec, F. King, R.E. Kirby, M.T.F. Pivi
SLAC, Menlo Park, California
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In the beam pipe of the positron damping ring of the Next Linear Collider, electrons will be created by beam interaction with the surrounding vacuum chamber wall and give rise to an electron cloud. Several solutions are possible for avoiding the electron cloud, without changing the beam bunch structure or the diameter of the vacuum chamber. Some of the currently available solutions include reducing residual gas ionization by the beam, minimizing photon-induced electron production, and lowering the secondary electron yield (SEY) of the chamber wall. We will report on recent SEY measurements performed at SLAC on TiN coatings and TiZrV non-evaporable getter thin films.
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| WEPKF085 |
Secondary Electron Emission Measurements for TiN Coating on Stainless Steel of SNS Accumulator Ring Vacuum Chamber
|
1804 |
| |
- P. He, H.-C. Hseuh, R. Todd
BNL, Upton, Long Island, New York
- B. Henrist, N. Hilleret
CERN, Geneva
- S. Kato, M. Nishiwaki
KEK, Ibaraki
- R.E. Kirby, F. Le Pimpec, M.T.F. Pivi
SLAC, Menlo Park, California
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BNL is responsible for the design and construction of the US Spallation Neutron Source (SNS) accumulator ring. Titanium Nitride(TiN) coating on the stainless steel vacuum chamber of the SNS accumulator ring is needed to reduce undesirable resonant multiplication of electrons. The Secondary Electron Yield(SEY) of TiN coated chamber material has been measured after coated samples were exposed to air and after electron and ion conditioning. We are reporting about the TiN coating system setup at BNL and SEY measurements results performed at CERN, SLAC and KEK. We also present updated electron-cloud simulation results for the SNS accumulator assuming different SEY values.
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| THPLT163 |
High-temperature Kicker Electrodes for High-beam-current Operation of PEP-II
|
2840 |
| |
- U. Wienands, R. Akre, D.E. Anderson, S. Debarger, K. Fant, D. Kharakh, R.E. Kirby, A. Krasnykh, A. Kulikov, J. Langton
SLAC, Menlo Park, California
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The strip line electrodes of the kickers used in the transverse bunch-by-bunch feedback systems see significant power deposition by beam and HOM-induced currents. This leads to elevated temperatures of the aluminum electrodes and will ultimately become a limit for the beam current in the Low Energy Ring. Heat is transported to the environment primarily by radiation from the blackened surface of the electrodes. In order to extend the beam-current range of these kickers, new electrodes have been fabricated from molybdenum which are able to run at significantly higher temperature, thus greatly increasing the efficiency of the radiative cooling of the electrodes. Blackening of the electrodes is achieved by oxidation in air at 1000°F using a recipe first applied in aviation research for supersonic aircraft. Emissivity was measured on coupons and a whole electrode to be about 0.6. In addition, the match at the terminations of the electrodes is improved following field calculations and measurements on a model of the kicker.
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