Measurements of the Electron Cloud Density in the PEP-II Low Energy Ring

Conference · Sun Jun 01 04:00:00 EDT 2008

OSTI ID:961594

Byrd, John; De Santis, Stefano; Sonnad, Kiran; Caspers, Fritz; Kroyer, Tom; Krasnykh, Anatoly; Pivi, Mauro

Clouds of low energy electronsin the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of these accelerators, it is difficult to probe the low energyelectron clouds over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave that is independently excited and transmitted over a section of the accelerator. We infer the absolute phase shift with relatively high accuracy from the phase modulation of the transmission due to the modulation of the electron cloud density from a gap in the positively charged beam. We have used this technique for the first time to measure the average electron cloud density over a 50 m straight section in the positron ring of the PEP-II collider at the Stanford Linear Accelerator Center. We have also measured the variation of the density by using low field solenoid magnets to control the electrons.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: Accelerator& Fusion Research Division
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 961594
• Report Number(s): LBNL-976E
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ACCELERATORS
ACCURACY
CHARGED PARTICLES
CLOUDS
ELECTRONS
Electron cloud
Diagnostics
Microwave.
MAGNETS
MODULATION
PHASE SHIFT
POSITRONS
PROBES
SOLENOIDS
STANFORD LINEAR ACCELERATOR CENTER