Simulation of the Electron Cloud for Various Configurations of a Damping Ring for the ILC

In the beam pipe of the positron damping ring of the International Linear Collider (ILC), an electron cloud may be first produced by photoelectrons and ionization of residual gases and then increased by the secondary emission process. This paper reports the assessment of electron cloud effects in a number of configuration options for the ILC baseline configuration. Careful estimates were made of the secondary electron yield threshold for electron cloud build-up, and the related singleand coupled-bunch instabilities, as a function of beam current and surface properties for a variety of optics designs. When the configuration for the ILC damping rings was chosen at the end of 2005, the results from these studies were important considerations. On the basis of the theoretical and experimental work, the baseline configuration currently specifies a pair of 6 km damping rings for the positron beam, to mitigate the effects of the electron cloud that could present difficulties in a single 6 km ring. Work presented at the European Particle Accelerator Conference EPAC'06, Edinburgh, United Kingdom, 26-30 June 2006. *Work supported by the Director, Office of Science, High Energy Physics, U.S. DOE under Contract No. DE-AC02-76SF00515 and the Commission of the European Communities Contract No. RIDS-011899. # [email protected] SIMULATION OF THE ELECTRON CLOUD FOR VARIOUS CONFIGURATIONS OF A DAMPING RING FOR THE ILC* M. Pivi , L. Wang, SLAC, Menlo Park, CA 94025, USA. K. Ohmi, KEK, Japan. R. Wanzenberg, DESY, Germany. A. Wolski, University of Liverpool and the Cockcroft Institute, UK. F. Zimmermann, CERN, Geneva, Switzerland.