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Absolute Measurement of Electron Cloud Density.

DE2007910204

Publication Date	2007
Personal Author	Covo, M. K.; Molvik, A. W.; Cohen, R. H.; Friedman, A.; Seidl, P. A.; Logan, G.; Bieniosek, F.
Page Count	7
Abstract	Beam interaction with background gas and walls produces ubiquitous clouds of stray electrons that frequently limit the performance of particle accelerator and storage rings. Counterintuitively we obtained the electron cloud accumulation by measuring the expelled ions that are originated from the beam-background gas interaction, rather than by measuring electrons that reach the walls. The kinetic ion energy measured with a retarding field analyzer (RFA) maps the depressed beam space-charge potential and provides the dynamic electron cloud density. Clearing electrode current measurements give the static electron cloud background that complements and corroborates with the RFA measurements, providing an absolute measurement of electron cloud density during a 5 is duration beam pulse in a drift region of the magnetic transport section of the High-Current Experiment (HCX) at LLNL.
Keywords	Density Electron clouds Kinetic ion energy Storage rings Particle accelerators Expelled ions Absolute measurement Electron cloud accumulation Retarding field analyzers High-Current Experiment (HCX) Lawrence Livermore National Laboratory (NLNL)
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Lawrence Livermore National Lab., CA.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200725

Absolute Measurement of Electron Cloud Density.

Absolute Measurement of Electron Cloud Density.
DE2007910204

Publication Date	2007
Personal Author	Covo, M. K.; Molvik, A. W.; Cohen, R. H.; Friedman, A.; Seidl, P. A.; Logan, G.; Bieniosek, F.
Page Count	7
Abstract	Beam interaction with background gas and walls produces ubiquitous clouds of stray electrons that frequently limit the performance of particle accelerator and storage rings. Counterintuitively we obtained the electron cloud accumulation by measuring the expelled ions that are originated from the beam-background gas interaction, rather than by measuring electrons that reach the walls. The kinetic ion energy measured with a retarding field analyzer (RFA) maps the depressed beam space-charge potential and provides the dynamic electron cloud density. Clearing electrode current measurements give the static electron cloud background that complements and corroborates with the RFA measurements, providing an absolute measurement of electron cloud density during a 5 is duration beam pulse in a drift region of the magnetic transport section of the High-Current Experiment (HCX) at LLNL.
Keywords	Density Electron clouds Kinetic ion energy Storage rings Particle accelerators Expelled ions Absolute measurement Electron cloud accumulation Retarding field analyzers High-Current Experiment (HCX) Lawrence Livermore National Laboratory (NLNL)
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Lawrence Livermore National Lab., CA.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200725