| Paper |
Title |
Page |
| MOPCH078 |
Simulation of Dynamic Vacuum Induced Beam Loss
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211 |
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- C. Omet, P.J. Spiller, J. Stadlmann
GSI, Darmstadt
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In synchrotrons, operated with intermediate charge state, heavy ion beams, intensity dependent beam losses have been observed. The origin of these losses is the change in charge state of the beam ions at collisions with residual gas atoms or molecules. The resulting A/Z deviation from the reference beam ion leads to modified trajectories in dispersive elements, which finally results in beam loss. At the impact positions, secondary particles are produced by ion stimulated desorption and increase the vacuum pressure locally. In turn, this pressure rise will enhance the charge change- and particle loss process and finally cause significant beam loss within a very short time (a few turns). A program package has been developed, which links the described beam loss mechanisms to the residual gas status and determines the vacuum dynamics. Core of the program is an ion optics tracking routine, in which the atomic physics and vacuum effects are embedded.
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| MOPCH079 |
Ion Optical Design of the Heavy Ion Synchrotron SIS100
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214 |
| |
- J. Stadlmann, K. Blasche, B. Franczak, C. Omet, N. Pyka, P.J. Spiller
GSI, Darmstadt
- A.D. Kovalenko
JINR, Dubna, Moscow Region
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We present the ion optical design of SIS100, which is the main synchrotron of the FAIR project. The purpose of SIS100 is the acceleration of high intensity heavy ion and proton beams and the generation of short compressed single bunches for the production of secondary beams. Since ionization in the residual gas is the main loss mechanism, a new lattice design concept had to be developed, especially for the operation with intermediate charge state heavy ions. The lattice was optimized to generate a peaked loss distribution in charge separator like lattice cells. Thereby it enables the control of generated desorption gases in special catchers. For bunch compression, the lattice provides dispersion free straight sections and a low dispersion in the arcs. A special difficulty is the optical design for fast and slow extraction, and the emergency dumping of the high rigidity ions within the same short straight section.
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| MOPCH089 |
Basic Aspects of the SIS100 Correction System Design
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240 |
| |
- V.A. Mikhaylov, A.V. Alfeev, A.V. Butenko, A.V. Eliseev, H.G. Khodzhibagiyan, A.D. Kovalenko, O.S. Kozlov, V.V. Seleznev, A.Y. Starikov, V. Volkov
JINR, Dubna, Moscow Region
- E. Fischer, P.J. Spiller, J. Stadlmann
GSI, Darmstadt
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The basic concept and the main design features of the superconducting SIS100 correction system are presented. The system comprises 84 steerer magnets consisting of two orthogonal dipole windings each for correction of the beam close orbit in vertical and horizontal planes, 48 normal sextupole windings connected in two families with opposite polarities for chromaticity correction and 12 units containing skew quadrupoles, normal and skew sextupoles and octupoles as well. The correction system should operate in a pulse mode corresponding to the accelerator cycle, i.e., up to 1 Hz. The main magnetic, geometrical and electrical parameters of the corrector magnets were specified. They are based on the beam dynamic analysis within the frames of the DF-type SIS100 lattice at different betatron tune numbers and tolerable alignment and manufacturing errors of the main lattice dipole and quadrupole magnets. The problem of reasonable unification of the corrector modules is discussed also, including their geometrical sizes, maximum supply current and cooling at 4.5 K. The concept of the SIS100 corrector magnets is based on the pulsed correctors designed for the Nuclotron.
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| THPCH005 |
Considerations for the High-intensity Working Point of the SIS100
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2793 |
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- G. Franchetti, O. Boine-Frankenheim, I. Hofmann, V. Kornilov, P.J. Spiller, J. Stadlmann
GSI, Darmstadt
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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.
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