Theory, Codes, Simulations

Beam Dynamics, Other

Paper	Title	Page
TUP26	Alternating Phase Focusing in Low-Velocity Heavy-Ion Superconducting Linac	348
	P.N. Ostroumov, K.W. Shepard ANL/Phys, Argonne, Illinois A. Kolomiets ITEP, Moscow E.S. Masunov MEPhI, Moscow
	The low-charge-state injector linac of the RIA post-accelerator is based on ~60 independently phased SC resonators providing total ~70 MV accelerating potential. The low charge-state beams, however, require stronger transverse focusing, particularly at low velocities, than is used in existing SC ion linacs. For the charge-to-mass ratios considered here (q/A = 1/66) the proper focusing can be reached by the help of strong SC solenoid lenses with the field up to 15 T. Magnetic field of the solenoids can be reduced to 9 T applying an Alternating Phase Focusing (APF). A method to set the rf field phases has been developed and studied both analytically and by the help of the three-dimensional ray tracing code. The paper discusses the results of these studies.
TUP27	Acceleration of Several Charge States of Lead Ion in CERN LINAC3	351
	V. Coco, J.A. Chamings, A.M. Lombardi, E.Zh. Sargsyan, R. Scrivens CERN, Geneva
	CERN’s LINAC3 is designed to accelerate a 100 μAe Pb25+ ion beam from 2.5 keV/u to 4.2 MeV/u. The beam is then stripped using a carbon foil and the resulting 25 μAe 54+ beam is accumulated and cooled in the Low Energy Ion Ring (LEIR) before transfer to the Proton Synchrotron (PS) and ultimately to the Large Hadron Collider (LHC). The Pb25+ ions are selected with a spectrometer from a mixture of ten charge states produced by an Electron Cyclotron Resonance (ECR) source. In view of the fact that the stripping efficiency to Pb54+ is mostly dependent on energy and not on initial charge state, the feasibility of simultaneously accelerating to 4.2 MeV/u several charge states has been investigated. In this paper we report two possible technical solutions, their advantage in terms of intensity for the downstream machines and the experimental results supporting these conclusions.
TUP29	Proton Beam Dynamics of the SARAF Linac	354
	A. Shor, D. Berkovits, G. Feinberg, S. Halfon SOREQ, Yavne K. Dunkel ACCEL, Bergisch Gladbach
	We have performed proton beam dynamics simulation for the SARAF, 40 MeV and 4 mA, linac. The calculation is using the GPT code and includes effects of space charge. It demonstrates that for an initial 6D Waterbag distribution beam, a tune can be obtained with longitudinal rms emittance growth of about 10 % and transverse normalized rms emittance growth of 20%, and a transverse beam envelope of 5000 macro-particle well within the linac beam pipe. Beam loss is estimated by fitting a radial Gaussian to the particle distribution along the linac. A 1 nA beam envelope is obtained by extrapolating the tail of the radial-Gaussian function. The 1nA beam envelope is still well within the beam bore radius. Benchmark simulation with a 6D Gaussian initial distribution, with the same rms quantities, exhibits a more extended tail that may result in a higher beam loss. This point will receive a further study.
	Transparencies
TUP56	Simulation of RF Breakdown Effects on NLC Beam	396
	V.A. Dolgashev SLAC/ARDB, Menlo Park, California T.O. Raubenheimer SLAC/NLC, Menlo Park, California
	The linacs of the Next Linear Collider (NLC) will contain several thousand traveling wave X-Band accelerator structures operating at input power of about 60 MW. At this input power prototypes of NLC structures have breakdown rates lower than one breakdown in ten hours. RF breakdowns disrupt flow of energy inside the structure and create arcs with electron and ion currents. Electromagnetic fields of these currents interact with the NLC beam. We simulated deflection of the NLC beam caused by breakdown currents using the particle-in-cell code MAGIC. In this paper we present modeling considerations and simulation results.
TUP58	Alternative Linac Layout for European XFEL Project	399
	Y. Kim, K. Flöttmann, T. Limberg DESY, Hamburg Y. Kim, D. Son CHEP Korea, Daegu
	To satisfy required beam parameters and to increase the jitter tolerance, we have designed an alternative linac layout with two bunch compressor stages for the European XFEL project. In this paper, we describe start-to-end (S2E) simulation of the alternative linac layout for the European XFEL project, and compare its results with our current linac layout with one bunch compressor stage.
TUP59	Extraction of High Charge Electron Bunch from the ELSA RF Injector - Comparison Between Simulation and Experiment	402
	J. Lemaire, P. Balleyguier, A. Binet, J.M. Lagniel, V. Le Flanchec, N. Pichoff CEA/DAM, Bruyères-le-Châtel R. Bailly-Salins, M. Millerioux, Chr. Quine CEA/DIF/DPTA/SP2A, Bruyeres-le-Chatel
	A new scheme based on a photoinjector and a RF linear accelerator operating at 352 MHz has been recently proposed as a versatile radiographic facility. Beam pulses of 60 ns duration contain 20 succesive electron bunches which will be extracted at 2.5 MeV from a photoinjector then accelerated through the next structure to the final energy of 51 MeV. Bunches carrying 100 nC are required for this purpose. As a first demonstrating step, 50 nC electron bunches have been produced and accelerated to 2.5 MeV with the 144 MHz ELSA photoinjector at Bruyères le Chatel. For this experiment, we compare the results and the numerical simulations made with PARMELA, MAGIC and MAFIA codes.
TH204	End-to-End Beam Dynamics Simulations for the ANL-RIA Driver Linac	584
	P.N. Ostroumov ANL/Phys, Argonne, Illinois
	The proposed Rare Isotope Accelerator (RIA) Facility consists of a superconducting (SC) 1.4 GV driver linac capable of producing 400 kW beams of any ion from hydrogen to uranium. The driver is configured as an array of ~350 SC cavities, each with independently controllable rf phase. For the end-to-end beam dynamics design and simulation we use a dedicated code, TRACK. The code integrates ion motion through the three-dimensional fields of all elements of the driver linac beginning from the exit of the electron cyclotron resonance (ECR) ion source to the production targets. TRACK has been parallelized and is able to track large number of particles in randomly seeded accelerators with misalignments and a comprehensive set of errors. The simulation starts with multi-component dc ion beams extracted from the ECR. Beam losses are obtained by tracking up to million particles in hundreds of randomly seeded accelerators. To control beam losses a set of collimators is applied in designated areas. The end-to-end simulations with the TRACK code have been extremely useful for studies of different options of the driver linac design with respect to beam quality, beam losses and sensitivity of beam parameters to various types of errors.
	Transparencies
TH302	End-to-End Beam Simulations for the MSU RIA Driver Linac	594
	X. Wu, M. Doleans, D. Gorelov, T.L. Grimm, F. Marti, R.C. York, Q. Zhao NSCL, East Lansing, Michigan
	The Rare Isotope Accelerator (RIA) driver linac proposed by Michigan State University (MSU) will use a 10th sub-harmonic based, superconducting, cw linac to accelerate light and heavy ions to final energies of ≤400 MeV/u with beam powers of 100 to 400 kW. The driver linac uses superconducting quarter-wave, half-wave, and six-cell elliptical cavities with frequencies ranging from 80.5 MHz to 805 MHz for acceleration, and superconducting solenoids and room temperature quadrupoles for transverse focusing. For the heavier ions, two stages of charge-stripping and multiple-charge-state acceleration will be used to meet the beam power requirements and to minimize the requisite accelerating voltage. End-to-end, three-dimensional (3D), beam dynamics simulations from the ECR to the radioactive beam production targets have been performed. These studies include a 3D analysis of multi-charge-state beam acceleration, evaluation of transverse misalignment and rf errors on the machine performance, modeling of the charge-stripping and stripping-chicane performance, and beam switchyard design. The results of these beam dynamics studies will be presented, and further planned beam dynamics studies will be discussed.
	Transparencies