Bonn 2010 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 60: Beschleunigerphysik IX
HK 60.8: Talk
Thursday, March 18, 2010, 18:35–18:50, HG ÜR 8
Electron cloud studies for SIS-18 and for the FAIR synchrotrons. — •Fedor Petrov1, Thomas Weiland1, and Oliver Boine-Frankenheim2 — 1Technische Universität Darmstadt, Institut für Theorie Elektromagnetischer Felder (TEMF) Schlossgartenstrasse 8, 64289 Darmstadt, Germany — 2Gesellschaft für Schwerionenforschung (GSI) GmbH, Planckstraße 1, D-64291 Darmstadt, Germany
Electron clouds generated by residual gas ionization pose a potential threat to the stability of the circulating heavy ion beams in the existing SIS-18 synchrotron and in the projected SIS-100. The electrons can potentially accumulate in the space charge potential of the long bunches. As an extreme case we study the accumulation of electrons in a coasting beam under conditions relevant in the SIS-18. Previous studies of electron clouds in coasting beams used Particle-In-Cell (PIC) codes to describe the generation of the cloud and the interaction with the ion beam. PIC beams exhibit much larger fluctuation amplitudes than real beams. The fluctuations heat the electrons. Therefore the obtained neutralization degree is strongly reduced, relative to a real beam. In our simulation model we add a Langevin term to the electron equation of motion in order to account for the heating process. The effect of natural beam fluctuations on the neutralization degree is studied. The modification of the beam response function as well as the stability limits in the presence of the electrons is discussed.