Impedance Studies for the Phase 2 LHC Collimators (2009)
Métral, E, Caspers, F, Grudiev, A, Kroyer, T, Zotter, B, Roncarolo, F, ...
The LHC phase 2 collimation project aims at gaining a factor ten in cleaning efficiency, robustness and impedance reduction. From the impedance point of view, several ideas emerged during the last...
Barnes, M J, Caspers, F, Kroyer, T, Métral, E, Roncarolo, F, Salvant, B
Fast kicker magnets are used to inject beam into and eject beam out of the CERN SPS accelerator ring. These kickers are generally ferrite loaded transmission line type magnets with a rectangular...
Measurements of the Electron Cloud Density in the PEP-II Low Energy Ring (2009)
Byrd, J, De Santis, S, Sonnad, K, Caspers, F, Kroyer, T, Krasnykh, A, ...
Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of...
BEAM INDUCED HEATING OF THE SPS FAST PULSED MAGNETS (2009)
J. Uythoven, G. Arduini, T. Bohl, F. Caspers, E. H. Gaxiola, T. Kroyer, ...
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...
Pivi, M T F, Krasnykh, A K, Byrd, J, De Santis, S, Sonnad, K G, Caspers, F, ...
Clouds of electrons in the vacuum chambers of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of...
Beam Coupling Impedance Measurement and Mitigation for a Totem Roman Pot (2008)
Deile, M, Caspers, F, Kroyer, T, Oriunno, M, Radermacher, E, Roncarolo, F, ...
The longitudinal and transverse beam coupling impedance of the first final TOTEM Roman Pot unit has been measured in the laboratory with the wire method. For the evaluation of transverse impedance...
Electron Cloud Mitigation by Fast Bunch Compression in the CERN PS (2008)
Damerau, H, Hancock, S, Kroyer, T, Mahner, E, Schokker, M
A fast transverse instability has been observed with nominal LHC beams in the CERN Proton Synchrotron (PS) in 2006. The instability develops within less than 1 ms, starting when the bunch length...
Albertone, J, Bartolome-Jimenez, S, Boccard, C, Bogey, T, Borowiec, P, Calvo, E, ...
Ensuring that the two 27km beam pipes of the LHC do not contain aperture restrictions is of utmost importance. Most of the ring is composed of continuous cryostats, so any intervention to remove...
Experimental Electron Cloud Studies in the CERN Proton Synchrotron (2008)
Mahner, E, Kroyer, T, Caspers, F
Indications for a beam-induced electron cloud build-up are observed since 2000 for the nominal LHC beam in the PS to SPS transfer line and during the last turns before ejection from the PS. A new...
Roncarolo, F, Caspers, F, Kroyer, T, Métral, E, Salvant, B
The prediction of the resistive wall transverse beam impedance at the first unstable betatron line (8 kHz) of the CERN Large Hadron Collider (LHC) is of paramount importance for understanding and...
Salvant, B, Caspers, F, Kroyer, T, Métral, E, Roncarolo, F
The low frequency longitudinal and transverse impedances of the CERN Large Hadron Collider (LHC) have to be specifically minimized to prevent the onset of coherent instabilities. The LHC beam vacuum...
RF Wire Compensator of Long-Range Beam-Beam Effects (2008)
Dorda, U, Caspers, F, Kroyer, T, Zimmermann, F
The dynamic aperture of the proton beam circulating in the Large Hadron Collider (LHC) is expected to be limited by up to 120 long-range beam-beam encounters. In order to perfectly compensate the LHC...
CERN SPS Impedance in 2007 (2008)
Métral, E, Arduini, Gianluigi, Bohl, T, Burkhardt, H, Calaga, R, Caspers, F, ...
Each year several measurements of the beam coupling impedance are performed in both longitudinal and transverse planes of the CERN Super Proton Synchrotron to keep track of its evolution. In...
Measurement of Electron Clouds in Large Accelerators by Microwave Dispersion (2008)
De Santis, S, Byrd, JM, Caspers, F, Krasnykh, A, Kroyer, T, Pivi, MTF, ...
Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation at high currents. Furthermore, it is difficult...
Characterization of the ATLAS Roman Pots Beam Coupling Impedance and Mechanics (2008)
Roncarolo, F, Caspers, F, Di Girolamo, B, Jones, RM, Kroyer, T
The 4.8 GHz LHC Schottky Pick-up System (2007)
Caspers, F, Hamerla, T, Jansson, A, Jiménez, J M, Jones, O R, Kroyer, T, ...
The LHC Schottky observation system is based on traveling wave type high sensitivity pickup structures operating at 4.8 GHz. The choice of the structure and operating frequency is driven by the...
Caspers, F, Kroyer, T, Kulka, J, Tock, J-P, Williams, L R
As part of the LHC assembly program, the super-conducting magnets are interconnected after installation. Electrical continuity between the magnets is ensured via a specifically designed cable...
The LHC Beam Pipe Waveguide Mode Reflectometer (2007)
Kroyer, T, Borowiec, P, Caspers, F, Sulek, Z, Williams, L R
The waveguide-mode reflectometer for obstacle detection in the LHC beam pipe has been intensively used for more than 18 months. The âﾜAssemblyâ version is based on the synthetic pulse...
Field Flucuation and Beam Screen Vibration Measurements in the LHC Magnets (2007)
De Maria, R, Kroyer, T, Shiltsev, V
We present experimental methods and results for the measurement of the magnetic field fluctuation and beam screen vibration in the LHC magnets. These noises can lead to an emittance growth in proton...
An Improved Beam Screen for the LHC Injection Kickers (2007)
Barnes, M J, Caspers, F, Ducimetière, L, Garrel, N, Kroyer, T
The two LHC injection kicker magnet systems must produce a kick of 1.3 T.m with a flattop duration variable up to 7860 ns, and rise and fall times of less than 900 ns and 3000 ns, respectively. Each...
Transverse Impedance of LHC Collimators (2007)
Métral, E, Arduini, Gianluigi, Assmann, Ralph Wolfgang, Boccardi, A, Bracco, C, Bohl, T, ...
The transverse impedance in the LHC is expected to be dominated by the numerous collimators, most of which are made of Fibre-Reinforced-Carbon to withstand the impacts of high intensity proton beams...
A New Type of distributed Enamel based Clearing Electrode (2007)
Kroyer, T, Behler, F J, Caspers, F, Hellmond, P, Métral, E, Wendel, J C, ...
Clearing electrodes can be used for electron cloud (EC) suppression in high intensity particle accelerators. In this paper the use of low and highly resistive layers on a dielectric substrate are...
The CERN SPL Chopper Structure. A Status Report (2007)
Kroyer, T, Caspers, F, Mahner, E
In the framework of HIPPI, a study for a Superconducting Proton Linac is being carried out at CERN. An integral part of the medium energy line is the chopper, which has to establish the required time...
Transverse impedance of LHC collimators (2007)
Metral, E, Arduini, G, Assmann, R, Boccardi, A, Bohl, T, Caspers, F, ...
The transverse impedance in the LHC is expected to be dominated by the numerous collimators, most of which are made of Fibre-Reinforced-Carbon to withstand the impacts of high intensity proton beams...
Linac4 Technical Design Report (2006)
Arnaudon, L, Baudrenghien, P, Baylac, M, Bellodi, G, Body, Y, Borburgh, J, ...
Linac4 is an H- linear accelerator, intended to replace Linac2 as injector to the PS Booster (PSB). By delivering to the PSB a beam at 160 MeV energy, Linac4 will provide the conditions to double the...
Status of the design of a Wide Band beam Current Monitor (WBCM) for EUROTeV (2006)
Caspers, F, Fandos, R, Jensen, E, Kroyer, T, Podadera-Aliseda, I, Soby, L, ...
In the framework of EUROTeV, the conceptual design of a new wide band wall current monitor is being carried out. The design is based on the wall current monitors presently installed in CTF3. The new...
The SPL (II) at CERN, a Superconducting 3.5 GeV H- Linac (2006)
Gerigk, F, Baylac, M, Bellodi, G, Benedico-Mora, E, Body, Y, Caspers, F, ...
A revision of the physics needs and recent progress in the technology of superconducting (SC) RF cavities have triggered major changes in the design of a SC H-linac at CERN. With up to 5MW beam...
Fault Detection and Identification Methods Used for the LHC Cryomagnets and Related Cabling (2006)
Bozzini, D, Caspers, F, Chareyre, V, Duse, Y, Kroyer, T, López, R, ...
Several methods for electrical fault location have been developed and tested. As part of the electrical quality assurance program for the LHC, certain wires have to be subjected to a (high) DC...
Tune shift induced by nonlinear resistive wall wake field of flat collimator (2006)
Zimmermann, Frank, Arduini, Gianluigi, Assmann, R W, Burkhardt, H, Caspers, F, Gasior, M, ...
We present formulae for the coherent and incoherent tune shifts due to the nonlinear resistive wall wake field for a single beam traveling between two parallel plates. In particular, we demonstrate...
The Beam Screen for the LHC Injection Kicker Magnets (2006)
Barnes, MJ, Caspers, F, Ducimetière, L, Garrel, N, Kroyer, T
The two LHC injection kicker magnet systems must each produce a kick of 1.2 T.m with a flattop duration variable up to 7.86 ìs, and rise and fall times of less than 0.9 ìs and 3 ìs, respectively....
The SPS Fast Extraction Kicker System in LSS6 (2006)
Gaxiola, E, Caspers, F, Ducimetière, L, Faure, P, Kroyer, T, Versolatto, B, ...
A new fast extraction has been set up in SPS LSS6 to transfer 450 GeV/c protons as well as ions to Ring 1 of the LHC, via the transfer line TI 2. The system includes four travelling wave kicker...
Operational experience with the LHC waveguide mode reflectometer (2006)
Borowiec, P, Caspers, F, Kroyer, T, Sulek, Z, Williams, L
The LHC microwave mode reflectometer (assembly version) reached operational status by the autumn of 2005. It is now routinely used in the LHC tunnel and on the surface to take data on the beam...
Application of Waveguide Mode Diagnostics for Remote Sensing in Accelerator Beam Pipes (2005)
Kroyer, T, Scholtz, A L, Caspers, F
In this work, two remote sensing systems using waveguide modes in beam pipes of CERN accelerators are studied. The first is an application of time domain reflectometry in waveguides. Since the...
Results from the SPS 1.7 GHz travelling wave schottky monitor (2005)
Castro, M E, Caspers, F, Kroyer, T, Jones, R, Koutchouk, Jean-Pierre, Tranquille, G
A 1.7 GHz waveguide Schottky detector system was recently built and installed in the SPS accelerator following the design of the detectors of the Fermilab Tevatron and Recycler accelerators. The...
A Retrofit Technique for Kicker Beam-Coupling Impedance Reduction (2004)
Caspers, Friedhelm, Gaxiola, E, Kroyer, T, Timmins, M, Uythoven, J, Kurennoy, S
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...
Coupler Structures for the LHC Beam Pipe Waveguide Mode Reflectometer (2004)
Caspers, Friedhelm, Kroyer, T, Wien, T U
The LHC reflectometer will be used to detect and localise obstacles and other kinds of discontinuities in the LHC beam screen. An important part of this device is the RF coupler element, which...
Beam Induced Heating of the SPS Fast Pulsed Magnets (2004)
Arduini, Gianluigi, Bohl, T, Caspers, Friedhelm, Gaxiola, E H, Kroyer, T, Timmins, M, ...
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...
A waveguide High Order Mode Reflectometer for the Large Hadron Collider Beam-pipe (2003)
The feasibility of a waveguide mode reflectometer for the LHC beam-pipe has been studied. After a start-up phase devoted to getting some experience with network analysers and waveguide calibration,...