Hofmann, I.

Paper	Title	Page
WEXFI01	Instabilities and Space Charge Effects in High Intensity Ring Accelerators	1882
	O. Boine-Frankenheim, I. Hofmann, V. Kornilov GSI, Darmstadt
	This presentation will review beam dynamics in circular accelerators with high beam intensity and space charge effects. The main focus will be on recent theoretical and experimental results related to collective instabilities and resonance crossing with space charge. In the first part of the presentation, the effect of space charge on collective instability thresholds and impedance budgets will be discussed. In this context the effect of space charge induced mode coupling on the longitudinal microwave instability will be illustrated. The stability of longitudinal bunched beam modes and of transverse dipole modes in the presence of space charge will be discussed. Recent work related to the transverse mode coupling instability (TMCI) with space charge will be reviewed. In the second part of the presentation, "incoherent" space charge effects on transverse nonlinear dynamics issues, like nonlinear resonance crossing, will be reviewed.
	Transparencies
THPCH004	Space Charge Induced Resonance Trapping in High-intensity Synchrotrons	2790
	G. Franchetti, I. Hofmann GSI, Darmstadt
	With the recent development of high-intensity circular accelerators, the simultaneous presence of space charge and lattice nonlinearities has gained special attention as possible source of beam loss. In this paper we present our understanding of the role of space charge and synchrotron motion as well as chromaticity for trapping of particles into the islands of nonlinear reonances. We show that the three effects combined can lead to significant beam loss, where each individual effect leads to small or negligible loss. We apply our findings to the SIS100 of the FAIR project, where the main source of field nonlinearities stems from the pulsed super-conducting dipoles, and the beam dynamics challenge is an extended storage at the injection flat-bottom, over almost one second, together with a relatively large space charge tune shift.
THPCH005	Considerations for the High-intensity Working Point of the SIS100	2793
	G. Franchetti, O. Boine-Frankenheim, I. Hofmann, V. Kornilov, P.J. Spiller, J. Stadlmann GSI, Darmstadt
	In the FAIR project the SIS100 synchrotron is foreseen to provide high-intensity beams of U 28+, including slow extraction to the radioactive beam experimental area, as well as high-intensity p beams for the production of antiprotons. In this paper we discuss the proposal of three different working points, which should serve the different needs: (1) a high intensity working point for U28+; (2) a slow extraction working point (also U28+); (3) a proton operation working point to avoid transition crossing. The challenging beam loss control for all three applications requires a careful account of the effects of space charge, lattice nonlinearities and chromaticity, which will be discussed in detail in this paper. Since tunes are not split by an integer and the injected emittances are different, the Montague stop-band needs to be avoided. Moreover, final bunch compression for the U beam requires a sufficiently small momentum spread, and the risk of transverse resisitive wall instabilities poses further limitations on our choice of working points.
THPCH006	Scaling Laws for the Montague Resonance	2796
	I. Hofmann, G. Franchetti GSI, Darmstadt
	The space-charge-driven Montague resonance is a source of emittance coupling in high-intensity accelerators with un-split tunes. Here we present scaling laws for the stop-band widths, growth rates and crossing behavior of this fourth order resonance. Our results on the coupling can be applied to circular machines as well as to linear accelerators. Based on self-consistent coasting beam simulation we show that for slow crossing of the stop-bands a strong directional dependence exists: in one direction the exchange is smooth and reversible, in the other direction it is discontinuous. We also discuss the combined effect of the Montague resonance and linear coupling by skew quadrupoles.
THPCH034	Transverse Coupling Impedances From Field Matching in a Smooth Resistive Cylindrical Pipe for Arbitrary Beam Energies	2853
	A.M. Al-Khateeb, A.M. Al-Khateeb, W.M. Daqa Yarmouk, Irbid O. Boine-Frankenheim, R.W. Hasse, I. Hofmann GSI, Darmstadt
	The transverse coupling impedance is investigated analytically. For an off-axis motion of the beam, the perturbed charge distribution of the beam becomes a function of the azimuthal angle, resulting to first order in the beam displacement in a dipole term which is the source of the transverse impedance. All six components of the electromagnetic field are different from zero and, therefore, both TM and TE modes will be excited in the beam-pipe and coupled to the beam at the inner surface of the resistive wall. Using the dipole source term, a linear combination of TM and TE modes is used to get closed form expressions for the transverse electromagnetic field components excited in the beam-pipe, and a generalized analytic expression for the corresponding transverse coupling impedance. It has been found that the contributions of the TM and the TE modes to the real part of the transverse resistive-wall impedance have similar dependence on the relativistic parameter but with opposite signs, the sum of both always being positive. Some approximate simple formulas for three important regions corresponding to small, intermediate and large frequencies in the ultrarelativistic limit were also obtained analytically.
WEPCH141	Accelerator Physics Code Web Repository	2254
	F. Zimmermann, R. Basset, E. Benedetto, U. Dorda, M. Giovannozzi, Y. Papaphilippou, T. Pieloni, F. Ruggiero, G. Rumolo, F. Schmidt, E. Todesco CERN, Geneva D.T. Abell Tech-X, Boulder, Colorado R. Bartolini Diamond, Oxfordshire O. Boine-Frankenheim, G. Franchetti, I. Hofmann GSI, Darmstadt Y. Cai, M.T.F. Pivi SLAC, Menlo Park, California Y.H. Chin, K. Ohmi, K. Oide KEK, Ibaraki S.M. Cousineau, V.V. Danilov, J.A. Holmes, A.P. Shishlo ORNL, Oak Ridge, Tennessee L. Farvacque ESRF, Grenoble A. Friedman LLNL, Livermore, California M.A. Furman, D.P. Grote, J. Qiang, G.L. Sabbi, P.A. Seidl, J.-L. Vay LBNL, Berkeley, California D. Kaltchev TRIUMF, Vancouver T.C. Katsouleas USC, Los Angeles, California E.-S. Kim PAL, Pohang, Kyungbuk S. Machida CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon J. Payet CEA, Gif-sur-Yvette T. Sen Fermilab, Batavia, Illinois J. Wei BNL, Upton, Long Island, New York B. Zotter Honorary CERN Staff Member, Grand-Saconnex
	In the framework of the CARE HHH European Network, we have developed a web-based dynamic accelerator-physics code repository. We describe the design, structure and contents of this web repository, illustrate its usage, and discuss our future plans.