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Title |
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MOPLT035 |
Beam Induced Heating of the SPS Fast Pulsed Magnets
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623 |
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- J.A. Uythoven, G. Arduini, T. Bohl, F. Caspers, E.H.R. Gaxiola, T. Kroyer, M. Timmins, L. Vos
CERN, Geneva
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Fast pulsed magnets with ferrite yokes are used in CERN?s SPS accelerator for beam injection, extraction and excitation for tune measurements. The impedance of the ferrite structures can provoke significant beam induced heating, especially for beams with high peak currents as for LHC operation, even beyond the Curie temperature. The expected heating in the different kicker systems for various operational modes is compared with beam measurements. Estimates of the beam induced power have been derived from measured beam spectra. A fast extraction kicker system has recently been equipped with a cooling system. The measured cooling performance is compared with data from laboratory setups and numerical simulations.
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TUPLT007 |
The CERN-SPL Chopper Concept and Final Layout
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1141 |
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- F. Caspers, Y. Cuvet, J. Genest, M. Haase, M. Paoluzzi, A. Teixeira
CERN, Geneva
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The fast chopper for the CERN SPL (Superconducting Proton Linac) consists of a double meander structure with a beta (v/c) value of 8 % printed on an alumina substrate for the deflecting plates. Each chopper unit is 50 cm long and housed in a quadrupole magnet surrounding the vacuum chamber. The deflecting plates are operated simultaneously in a dual mode, namely traveling wave mode for frequencies above about 10 MHz and as quasi electro-static deflectors below. The deflecting structures are water-cooled to handle heating from beam losses as well as from the deflecting signal. A detailed mechanical layout is presented including the tri-axial feeding and termination technique as well as a discussion of the drive amplifier
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TUPLT008 |
A Retrofit Technique for Kicker Beam-coupling Impedance Reduction
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1144 |
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- F. Caspers, E.H.R. Gaxiola, T. Kroyer, M. Timmins, J.A. Uythoven
CERN, Geneva
- S.S. Kurennoy
LANL/LANSCE, Los Alamos, New Mexico
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The reduction of the impedance of operational ferrite kicker structures may be desirable in order to avoid rebuilding such a device. Often resistively coated ceramic plates or tubes are installed for this purpose but at the expense of available aperture. Ceramic U-shaped profiles with a resistive coating fitting between the ellipse of the beam and the rectangular kicker aperture have been used to significantly reduce the impedance of the magnet, while having a limited effect on the available physical aperture Details of this method, constraints, measurements and simulation results as well as practical aspects are presented and discussed.
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WEPLT023 |
Transverse Resistive Wall Impedance and Wake Function with Inductive Bypass
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1873 |
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- A. Koschik, F. Caspers, E. Métral, L. Vos
CERN, Geneva
- B. Zotter
Honorary CERN Staff Member, Grand-Saconnex
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We analyze the resistive wall impedance with an "inductive bypass" due to alternate current paths in the outer vacuum chamber proper. Also the corresponding wake function has been obtained which is useful for the simulation of beam stability in the time domain. Results are presented for the LHC.
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THPLT014 |
Coupler Structures for the LHC Beam-pipe Waveguide Mode Reflectometer
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2490 |
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- T. Kroyer
TU Vienna, Vienna
- F. Caspers
CERN, Geneva
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The LHC reflectometer will be used to detect and localize obstacles and other kinds of discontinuities in the LHC beam screen. An important part of this device is the RF coupler element, which provides the interface between the circular beam screen and the measurement equipment. Two different scenarios of operation are considered. The first option consists in carrying out measurements during assembly by directly branching a coupler to the end of the beam screen. The other one is a permanent installation to be used in situ requiring a different kind of coupler to keep the aperture free. The goal is to achieve a reasonably well-matched spurious mode-free excitation over a 25% bandwidth for the TM01 and the T·1011 mode, respectively. The fulfillment of the required features is severely complicated by space and material restrictions arising mainly from vacuum and installation constraints.
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THPLT113 |
Conceptual Design of a Microwave Confocal Resonator Pick-up
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2747 |
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- V.G. Ziemann, A. Ferrari, T. Lofnes
TSL, Uppsala
- F. Caspers, I. Syratchev
CERN, Geneva
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A confocal resonator may be used as a pick-up for frequencies in the multi-GHz region. In this report we discuss the design by analytical and numerical methods of such a device. Furthermore we discuss engineering issues such as the damping of unwanted modes, shielding of image fields and manufacturing tolerances. Such a device can be used both as pick-up and kicker where the actual structure is several wavelengths away from the beam in the transverse direction. It is intended for highly relativistic beams and does not require changing particle trajectory as opposed to a diagnostic wiggler.
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