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New Chicane Experiment In PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders.

DE2008934750

Publication Date	2008
Personal Author	Pivi, M. T. F.; Kharakh, D.; Seeman, J.; Wittmer, W.; Celata, C. M.
Page Count	3
Abstract	Beam instability caused by the electron cloud has been observed in positron and proton storage rings, and it is expected to be a limiting factor in the performance of future colliders. The effect is expected to be particularly severe in magnetic field regions. To test possible mitigation methods in magnetic fields, we have installed a new 4-dipole chicane experiment in the PEP-II Low Energy Ring (LER) at SLAC with both bare and TiN-coated aluminum chambers. In particular, we have observed a large variation of the electron flux at the chamber wall as a function of the chicane dipole field. We infer this is a new high order resonance effect where the energy gained by the electrons in the positron beam depends on the phase of the electron cyclotron motion with respect to the bunch crossing, leading to a modulation of the secondary electron production. Presumably the cloud density is modulated as well and this resonance effect could be used to reduce its magnitude in future colliders. We present the experimental results obtained during January 2008 until the April final shut-down of the PEP-II machine.
Keywords	Particle accelerators Clouds Electrons Linear colliders Aluminium Synchrotrons Dipoles Instability Magnetic fields Mitigation Modulation Positron beams Positrons Protons Resonance Storage rings
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Stanford Linear Accelerator Center, CA.; Department of Energy, Washington, DC.; Lawrence Berkeley National Lab., CA.
Supplemental Notes	Prepared in cooperation with Lawrence Berkeley National Lab., CA. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200902
Contract Number	DE-AC02-76SF00515

New Chicane Experiment In PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders.

New Chicane Experiment In PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders.
DE2008934750

Publication Date	2008
Personal Author	Pivi, M. T. F.; Kharakh, D.; Seeman, J.; Wittmer, W.; Celata, C. M.
Page Count	3
Abstract	Beam instability caused by the electron cloud has been observed in positron and proton storage rings, and it is expected to be a limiting factor in the performance of future colliders. The effect is expected to be particularly severe in magnetic field regions. To test possible mitigation methods in magnetic fields, we have installed a new 4-dipole chicane experiment in the PEP-II Low Energy Ring (LER) at SLAC with both bare and TiN-coated aluminum chambers. In particular, we have observed a large variation of the electron flux at the chamber wall as a function of the chicane dipole field. We infer this is a new high order resonance effect where the energy gained by the electrons in the positron beam depends on the phase of the electron cyclotron motion with respect to the bunch crossing, leading to a modulation of the secondary electron production. Presumably the cloud density is modulated as well and this resonance effect could be used to reduce its magnitude in future colliders. We present the experimental results obtained during January 2008 until the April final shut-down of the PEP-II machine.
Keywords	Particle accelerators Clouds Electrons Linear colliders Aluminium Synchrotrons Dipoles Instability Magnetic fields Mitigation Modulation Positron beams Positrons Protons Resonance Storage rings
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Stanford Linear Accelerator Center, CA.; Department of Energy, Washington, DC.; Lawrence Berkeley National Lab., CA.
Supplemental Notes	Prepared in cooperation with Lawrence Berkeley National Lab., CA. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200902
Contract Number	DE-AC02-76SF00515