Paper |
Title |
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MOPP003 |
Study of Abnormal Vertical Emittance Growth in ATF Extraction Line
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553 |
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- M. Alabau, A. Faus-Golfe
IFIC (CSIC-UV), Valencia
- M. Alabau, P. Bambade, J. Brossard, G. Le Meur, C. Rimbault, F. Touze
LAL, Orsay
- D. Angal-Kalinin, J. K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
- R. Appleby, A. Scarfe
UMAN, Manchester
- S. Kuroda
KEK, Ibaraki
- G. R. White, M. Woodley
SLAC, Menlo Park, California
- F. Zimmermann
CERN, Geneva
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Since several years, the vertical emittance measured in the Extraction Line (EXT) of the Accelerator Test Facility (ATF) at KEK, that will transport the electron beam from the ATF Damping Ring (DR) to the future ATF2 Final Focus beam line, is significantly larger than the emittance measured in the DR itself, and there are indications that it grows rapidly with increasing beam intensity. This long-standing problem has motivated studies of possible sources of this anomalous emittance growth. One possible contribution is non-linear magnetic fields in the extraction region experienced by the beam while passing off-axis through magnets of the DR during the extraction process. In this paper, simulations of the emittance growth are presented and compared to observations. These simulations include the effects of predicted non-linear field errors in the shared DR magnets and orbit displacements from the reference orbit in the extraction region. Results of recent measurements using closed orbit bumps to probe the relation between the extraction trajectory and the anomalous emittance growth are also presented.
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TUPC028 |
Design and Construction of an Inductive Pick-up for Beam Position Monitoring in the TBL Line of the CTF3
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1110 |
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- J. J. Garcia-Garrigos, J. V. Civera-Navarrete, A. Faus-Golfe
IFIC (CSIC-UV), Valencia
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In order to determine the beam position respect to the vacuum chamber, the IPU senses the azimuthal distribution of the beam image current flowing along its inner wall when a high frequency bunched beam passes through. The inner wall of the pick-up is divided into four electrodes, each of which forms the primary winding of a toroidal transformer. Therefore the beam image current component flowing through each electrode is transformed to a secondary winding connected to a pick-up output. The closer the beam is to the transformer electrode, the greater is the induced signal in its secondary winding. This basic sensing mechanism will allow to determine the beam position through the four transformers distributed orthogonally around the vacuum pipe. The bandwidth of the IPU and the amplifier is set above 200 MHz to let pass, with low distortion, the 20-140 ns pulse train signal induced from the beam. Also, its expected resolution at maximum current is 5μm. This paper reports on the design, construction as well as testing and calibration processes of two IPU prototypes. They will be installed in the Test Beam Line (TBL) of the 3rd CLIC Test Facility (CTF3) at CERN by Spring 2008.
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