Paper 
Title 
Page 
MOPS068 
Localization of Transverse Impedance Sources in the SPS using HEADTAIL Macroparticle Simulations 
757 

 N. Biancacci, G. Arduini, E. Métral, D. Quatraro, G. Rumolo, B. Salvant, R. Tomás
CERN, Geneva, Switzerland
 N. Biancacci, M. Migliorati, L. Palumbo
Rome University La Sapienza, Roma, Italy
 R. Calaga
BNL, Upton, Long Island, New York, USA



In particle accelerators, beam coupling impedance is one of the main contributors to instability phenomena that lead to particle losses and beam quality deterioration. For this reason these machines are continuously monitored and the global and local amount of impedance needs to be evaluated. In this work we present our studies on the local transverse impedance detection algorithm. The main assumptions behind the algorithm are described in order to understand limits in reconstructing the impedance location. The phase advance response matrix is analyzed in particular for the SPS lattice, studying the different response from 90,180,270 degrees phase advance sections. The thin lenses scheme is also implemented and new analytical formulas for phase advance beating were derived. This avails us to put reconstructing lenses everywhere in the lattice, and to study their positioning scheme. Limits in linear response are analyzed. This sets the upper and lower limits in reconstruction to the phase advance measurement accuracy and the linear response regime limit.



MOPS073 
Impedance Calculation for Simple Models of Kickers in the Nonultrarelativistic Regime 
772 

 N. Biancacci, N. Mounet, E. Métral, B. Salvant, C. Zannini
CERN, Geneva, Switzerland
 N. Biancacci, M. Migliorati, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
 Q. Qin, N. Wang
IHEP Beijing, Beijing, People's Republic of China



Kicker magnets are usually significant contributors to the beam coupling impedance of particle accelerators. An accurate understanding of their impedance is required in order to correctly assess the machine intensity limitations. The field matching method derived by H. Tsutsui for the longitudinal and transverse dipolar (driving) impedance of simple models of kickers in the ultrarelativistic regime was already extended to the nonultrarelativistic case, and to the quadrupolar (detuning) impedance in the ultrarelativistic case. This contribution presents the extension to the quadrupolar impedance in the nonultrarelativistic case, as well as benchmarks with other available methods to compute the impedance. In particular, all the components of the impedances are benchmarked with Tsutsui's model, i.e. in the ultrarelativistic limit, with the model for a flat chamber impedance recently computed by N. Mounet and E. Métral, in the case of finite relativistic gamma, and with CST Particle Studio simulations.



WEPC107 
Development of a Steady State Simulation Code for Klystron Amplifiers 
2265 

 C. Marrelli
CERN, Geneva, Switzerland
 M. Migliorati, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
 B. Spataro
INFN/LNF, Frascati (Roma), Italy
 S.G. Tantawi
SLAC, Menlo Park, California, USA



The design of klystrons is based on the intensive utilization of simulation codes, which can evaluate the complete beamcavities interaction in the case of large signals. In the present work, we present the development of a 2D steady state simulation code that can selfconsistently evaluate the effects of the electromagnetic field on the particles and of the particles back on the field. The algorithm is based on the iterative solution of the power balance equation in the RF structures and allows determining the amplitude and phase of the electromagnetic field starting from the cavity modes. Some applications of the code to a single cavity and a two cavity klystron are presented and compared with the results obtained from other codes. The effect of the space charge forces in the klystron drift tubes is also evaluated.



TUPO008 
Electron Linac Optimization for Driving Bright Gammaray Sources based on Compton Backscattering 
1461 

 L. Serafini, F. Broggi, C. De Martinis, D. Giove
Istituto Nazionale di Fisica Nucleare, Milano, Italy
 D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, E. Chiadroni, G. Di Pirro, A. Esposito, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, P. Tomassini, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
 A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
 C. Maroli, V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
 M. Migliorati, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy



We study the optimal layout and RF frequency for a room temperature GeVclass Electron Linac aiming at producing electron beams that enhance gammaray sources based on Compton backscattering. These emerging novel sources, generating tunable, monochromatic, bright photon beams in the range of 520 MeV for nuclear physics as well as nuclear engineering, rely on both, high quality electron beams and Jclass high repetitionrate synchronized laser systems in order to achieve the maximum spectral density of the gammaray beam (# photons/sec/eV). The best option among the conventionally used RF linacbands (S, C, X) and possible hybrid schemes will be analyzed and discussed, focusing the study in terms of best performances for the gammaray source, its reliability and compactness. We show that the best possible candidates for a Gammaray driver are quite similar to those of FEL Linacs.



THYB01 
Advanced Beam Manipulation Techniques at SPARC 
2877 

 A. Mostacci, D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
 A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
 B. Marchetti
INFNRoma II, Roma, Italy
 M. Migliorati
University of Rome "La Sapienza", Rome, Italy
 L. Palumbo
Rome University La Sapienza, Roma, Italy
 V. Petrillo, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
 C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy



SPARC in Frascati is a high brightness photoinjector used to drive Free Electron Laser experiments and explore advanced beam manipulation techniques. The R&D effort made for the optimization of the beam parameters will be presented here, together with the major experimental results achieved. In particular, we will focus on the generation of subpicosecond, high brightness electron bunch trains via velocity bunching technique (the so called comb beam). Such bunch trains can be used to drive tunable and narrow band THz sources, FELs and plasma wake field accelerators.



Slides THYB01 [20.772 MB]


