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Ribbon Electron Beam Profile Monitor
For Bunched Beam Tomography
Muons, Inc.
Innovation in research
The Problem: Bunched Beam Tomography
Advanced accelerator beam diagnostics are essential for user
facilities that require intense proton beams with small
emittances and high reliability.
Important to have noninvasive diagnostics that can be used
continuously with intense accelerated beams.
Determination of particle distributions within an RF bunch is
one of the most difficult tasks of all.
Muons, Inc. Ribbon Electron Beam Profile Monitor (RPBM) For
Bunched Beam Tomography can address the challenges.
The Solution: Ribbon Electron Beam Profile
Monitor for Bunched Beams
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A short pulse of the extraction voltage can be used to produce a short time-slice of the
ribbon beam. After crossing the proton bunch with an angle close to 45o, the deflected
electrons are visualized on the luminescent screen (7) and recorded by a fast CCD
camera for further processed by corresponding software. Several similar systems can be
integrated for production of the tomographic 3-D image of proton bunches.
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Schematic diagram of a Ribbon e-Beam Profile Monitor with a strip cathode. 1- strip
cathode; 2-extractor; 3-anode with first slit of collimator; 4-deflecting plate; 5-second
slit of collimator; 6-ribbon time- slice of electron probe; 7-luminiscent screen.
RPBM Advantages
• Instead of scanning with a pencil electron beam as used in previous
profile monitors, a novel strip cathode is used to form a sheet or
ribbon beam of electrons to measure the density of a passing
bunch of particles.
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The strip cathode apparatus eliminates the need for quadrupoles,
is smaller with simpler design, is less expensive to manufacture, and
has better magnetic shielding, higher sensitivity, and higher spatial
and time resolutions.
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With this device, almost ideal tomography of bunches is possible in
linear accelerators, circular accelerators, and storage rings.
The Impact of the Technology
The detailed measurements enabled by the REPBM are important for optimizing high
intensity beam accumulation and acceleration and for suppressing instabilities in
order to increase beam luminosity and lifetime. The facilities that this will impact are:
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Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL),
Los Alamos Neutron Science Center (LANSCE) at LANL,
Project-X at the Fermi National Accelerator Laboratory
Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL),
National Superconducting Cyclotron Lab and Facility for Radioactive Ion Beams (FRIB) at
MSU,
Facility for Antiprotons and Ion Research (FAIR) at GSI, Darmstadt, Germany,
Japan Proton Accelerator Research Complex (J-PARC) in Japan and
Project-X, and next-generation projects at Fermi National Accelerator Lab (Fermilab)
European Spallation Neutron Source (ESS) in Lund, Sweden
Chinese Spallation Neutron Source at Dongguan in Guangdong province, China
MYRRHA: Multi-purpose hybrid research reactor for high-tech applications, in Mol,
Belgium
RPBM: Simulation of Electron Beam
Formation
Edge view of the strip cathode electron gun showing the simulation of ribbon electron
beam extraction, acceleration, and focusing by the deflector plates (extraction voltage
Uex=10 kV, Accelerating voltage Ua=100 kV, focusing voltage on the deflector system is
Uf=-5 kV). Red lines are electron trajectories, green lines are equipotentials. The scale is
1 mm/division.
RBPM Mechanical Design
electron-gun
Full System Mechanical Model
Electron-gun, extraction electrode,
accelerating anode and deflection plates
RBPM Component Tests
Electron-gun test in vacuum chamber
Ribbon electron beam on
luminescent screen
Next Steps
Ready to move to:
– System fabrication and beam testing
–Tomography development and readout
• Collaboration with National Instruments
• Based on PXI & NI FlexRIO technology (FPGA)