Abstracts Brochure - 2nd International Particle Accelerator Conference

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of measurements on various beam parameters. Comparison of the results between the measurement and the simulation is also presented. Poster Panel 62 ID: 3909 - MOPS023 An Analytical Lagragian Model for Analyzing Temperature Effects in Intense Non-neutral Beams, Everton Granemann Souza, Antonio Endler, Renato Pakter, Felipe Barbedo Rizzato (IF- UFRGS, Porto Alegre) - High-intensity chargedparticle beams are used in several areas of physics. We can mention as an illustration, high-energy colliders, particle accelerators and vacuum electron devices. In all cases quoted above, the beam lose particles in the acceleration process, between its production to its final destination. These ejected particles, generally, produce a surrounding structure around the beam core, called halo. This undesirable structure is seen in simulation as well as in actual linacs, and its formation has been one of the main sources of energy loss in the acceleration devices. For this reason, the need for an advance in understand the mechanism that produce the halo becomes necessary. In view of the whole problem, we contruct a 1D Lagrangian warm-fluid model for describe the behavior of inhomogeneous chargedparticle beam in solenoidal focusing magnetic field. The equations of motion are derived for an adiabatic process with a state equation originated from the ideal gas law. In the end, the model is compared with self-consistent simulation and is used to explain emittance growth and jets of particle, even when the system is out of equilibrium. Sub Classification: D04 High Intensity in Linear <strong>Accelerator</strong>s Poster Panel 63 ID: 4117 - MOPS010 Experimental Studies with Low Transition Energy Optics in the SPS, Hannes Bartosik, Theodoros Argyropoulos, Thomas Bohl, Stephane Cettour Cave, Karel Cornelis, Yannis Papaphilippou, Giovanni Rumolo, Benoit Salvant, Elena Shaposhnikova, Jorg Wenninger (CERN, Geneva) - The optics of the SPS can be tuned to lower transition energy such that the slippage factor at injection is raised by a factor of almost 3. From theory, an increase of the intensity thresholds for transverse mode coupling instabilities, longitudinal coupled bunch instabilities and longitudinal instabilities due to the loss of Landau damping can be expected. In this paper, experimental studies with � 19 LHC-type proton beams in the SPS with very high intensities of up to 3.5e11 p/b on the flat bottom and at 450 GeV/c are presented. In particular, the measurements address the increase of intensity thresholds and the achievable transverse emittances in the new low gamma transition optics with respect to the nominal SPS optics. The obtained results are compared with numerical simulations. Sub Classification: D05 Instabilities - Processes, Impedances, Countermeasures Poster Panel 64 ID: 3000 - MOPS078 Coaxial Wire Simulations of Ferrite Kicker Magnets, Hugo Alistair Day (CERN, Geneva; UMAN, Manchester), Michael John Barnes, Fritz Caspers, Elias Métral, Benoit Salvant, Carlo Zannini (CERN, Geneva), Roger Michael Jones (UMAN, Manchester) - Fast kicker magnets are used to inject beam into and eject beam out of the CERN accelerator rings. These kickers are generally transmission line type magnets with a rectangular shaped aperture through which the beam passes. Unless special precautions are taken the impedance of the yoke can provoke significant beam induced heating, especially for high intensities. In addition the impedance can contribute to beam instabilities. The results of longitudinal and transverse impedance measurements, for various kicker magnets, are presented and compared with analytical calculations: in addition predictions from a numerical analysis are discussed. Sub Classification: D05 Instabilities - Processes, Impedances, Countermeasures Poster Panel 65 ID: 4127 - MOPS060 Simulation of Resistive Wall Instabilities in CSNS/RCS, Liangsheng Huang (IHEP Beijing, Beijing) - Rapid Cycling Synchrotron (RCS�of The China Spallation Neutron Source (CSNS) is a high intensity proton accelerator, with average beam power of 100kW. The collective effects caused by the coupling impedance may be the limit to beam power. Based on the impedance estimation for components on beam line, the resistive wall impedance and its instability are more serious than any other instability. In this paper, a simple resistive wall wake field model is used to simulate the bunch oscillation and instability growth rate. In this model, the continuous resistive wall wake field is equivalent to points wake field along the RCS, and long bunch is sliced into many micro-bunches. By tracking the
dynamics of the micro-bunches, the transverse growth rate and beam size blow-up were obtained. Sub Classification: D05 Instabilities - Processes, Impedances, Countermeasures Poster Panel 66 ID: 4119 - MOPS075 Simulation of Multibunch Motion with the HEADTAIL Code and Application to the SPS and the LHC, Nicolas Mounet (CERN, Geneva; EPFL, Lausanne), Elias Métral, Giovanni Rumolo (CERN, Geneva) - Multibunch instabilities due to beam-coupling impedance can be a critical limitation for synchrotrons operating with many bunches. It is particularly true for the LHC under nominal conditions, where according to theoretical predictions the 2808 bunches rely entirely on the performance of the transverse feedback system to remain stable. To study these instabilities, the HEADTAIL code has been extended to simulate the motion of many bunches under the action of wake fields. All the features already present in the singlebunch version of the code, such as synchrotron motion, chromaticity, amplitude detuning due to octupoles and the ability to load any kind of wake fields through tables, have remained available. This new code has been then parallelized in order to track thousands of bunches in a reasonable amount of time. The code was benchmarked against theory and exhibited a good agreement. We also show results for bunch trains in the SPS and compare them with beam-based measurements. Sub Classification: D05 Instabilities - Processes, Impedances, Countermeasures Poster Panel 67 ID: 2927 - MOPS052 Analytical and Numerical Calculations of Beam Pipe Impedances at Low Frequencies with Application to the Thin SIS100 Pipe, Uwe Niedermayer, Oliver Boine-Frankenheim, Lukas Haenichen (TEMF, TU Darmstadt, Darmstadt) - The projected fast ramped synchrotron SIS100 for FAIR uses an elliptical stainless steel beam pipe of 0.3 mm thickness. The lowest coherent betatron sidebands reach down to 100 kHz which demands accurate impedance calculations in the low frequency (LF) regime. For these frequencies, i.e. skin depth greater than wall thickness, structures behind the pipe may contribute to the impedance. Due to the extremely large wake length numerical methods in the time domain are not applicable. The longitudinal and transverse impedance of the thin � 20 SIS100 beam pipe including structures behind the pipe are obtained numerically by a method using power loss in the frequency domain. We compare different analytical models for simplified pipe structures to the numerical results. The dc and ultrarelativistic limits are investigated. The interpretation of bench measurements in the LF regime is discussed. Sub Classification: D05 Instabilities - Processes, Impedances, Countermeasures Poster Panel 68 ID: 3691 - MOPS054 Impedance of the Kicker Power Supply for the SIS100 Synchrotron, Katarina Samuelsson, Volker Hinrichsen (TU Darmstadt, Darmstadt), Udo Blell, Jürgen Florenkowski, Isfried Josef Petzenhauser, Peter J. Spiller (GSI, Darmstadt) - SIS100 will be operated with high intensity heavyion and proton beams. The reduction of ring impedances is therefore of great importance in order to avoid coherent beam instabilities. The kicker system is one of the main contributors to the overall ring impedance in SIS100. This paper will focus on the contribution of the external network to the kicker impedance. Calculations as well as experimental impedance measurements of the network contribution have already been carried out for the SIS18 and ESR kickers. The SIS100 will be equipped with a bipolar kicker system, which uses a Pulse Forming Network (PFN) as energy storage. For potential detachment purposes an insulation transformer will be installed. Since this setup is new in several ways it is important to know its contribution to the coupling impedance of the kicker system. In this contribution the corresponding numerical calculation is presented. Sub Classification: D05 Instabilities - Processes, Impedances, Countermeasures Poster Panel 69 ID: 4528 - MOPS089 Identification of Bunch Dynamics in the Presence of E-Cloud and TMCI for the CERN SPS Ring, Ozhan Turgut, John Fox, Claudio Hector Rivetta (SLAC, Menlo Park, California) - Measurements and multi-particle simulation codes (i.e. HEAD- TAIL, WARP, CMAD) indicate that bunched particle beams show unstable motions induced by electron-clouds and strong head-tail interactions. The bunch dynamics exhibits highly non-linear, complex and unstable behavior under certain operating conditions. Feedback control systems have
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Abstracts Brochure - 2nd International Particle Accelerator Conference

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