IPAC2011 - List of Authors (Petrov, F.B.)

Paper	Title	Page
MOPS053	Electron Cloud Effects in Coasting Heavy-ion Beams*	724
	F.B. Petrov, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim GSI, Darmstadt, Germany
	Funding: Work supported by BMBF under contract 06DA9022I. During slow extraction of intense ion beams electron clouds (EC) can accumulate in the circulating coasting beam and reduce the extraction efficiency. This is a concern for the existing SIS-18 heavy ion synchrotron at GSI and for the projected SIS-100 as part of the FAIR project. For medium energy heavy-ion beams the production of electrons from residual gas ionization is very effective. The electron density is limited due to Coulomb scattering by the beam ions. Above a threshold beam intensity the two-stream instability and the resulting coherent beam oscillations limit the electron density. Below this threshold the electron cloud can lead to observable deformations of the Schottky side-bands. To avoid EC build-up one can introduce a gap in the beam using barrier rf bucket. The reduction of the build-up efficiency caused by the gap is studied in details based on the solution of the Hill's equation for electrons. Finally we estimate the saturation level for the electron cloud density.

Paper

Title

Page

Electron Cloud Effects in Coasting Heavy-ion Beams*

724

F.B. Petrov, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim
GSI, Darmstadt, Germany

Funding: Work supported by BMBF under contract 06DA9022I.
During slow extraction of intense ion beams electron clouds (EC) can accumulate in the circulating coasting beam and reduce the extraction efficiency. This is a concern for the existing SIS-18 heavy ion synchrotron at GSI and for the projected SIS-100 as part of the FAIR project. For medium energy heavy-ion beams the production of electrons from residual gas ionization is very effective. The electron density is limited due to Coulomb scattering by the beam ions. Above a threshold beam intensity the two-stream instability and the resulting coherent beam oscillations limit the electron density. Below this threshold the electron cloud can lead to observable deformations of the Schottky side-bands. To avoid EC build-up one can introduce a gap in the beam using barrier rf bucket. The reduction of the build-up efficiency caused by the gap is studied in details based on the solution of the Hill's equation for electrons. Finally we estimate the saturation level for the electron cloud density.