Post on 28-Mar-2015
Storage Rings for Charged Particles
Kai HockCockcroft Institute and University of Liverpool
Birmingham University, 24 February 2009
Birmingham, 24 Feb 09: Storage Rings 2
Outline
• Major uses of the charged particle storage rings
• Basic principles and designs
• Beam dynamics and stability
• Relevance to the atom storage ring
• Ideas for research and development
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Major uses of the charged particle storage rings
• Synchrotron light source– Stores electrons– Produces high quality radiation for scientific experiments
• Damping rings– Stores electrons or positrons– Produces very narrow beams for particle physics experiments
• Others– Storing muons to produce neutrinos– Cooling protons for particle physics experiments– Cooling ions for nuclear physics experiments, etc.
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The Diamond Synchrotron, Oxfordshire
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The ATF Damping Ring, Japan
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Basic Principles and Design
• Charged particles are guided in a vacuum pipe around a ring using dipole magnetic fields.
• They are strongly focused into bunches using quadrupole magnetic fields and rf cavity electric field – the key to stable circulation.
• Fine tuning to the focusing is made using sextupole magnets.• Energy is lost by radiation when particles are bent by
magnetic fields, or by collision with residual gas.• Energy is replenished in the rf cavity by electric fields in the
same direction as the particle orbit.• Diagnostic instruments are available to measure beam
position, beam profile and radiation profile.
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Damping Ring for the Linear Collider
injection extraction
e+
8 RF cavities
10 RF cavities
wiggler
wiggler
wiggler
IP
wiggler
accelerateparticles
alternating magneticfields to cool electrons
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Enabling Technologies
Beam position monitorQuadrupole magnet
WigglerDipole magnet Superconducting rf cavity
Sextupole magnet
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Basic Principles of Operation
15
23
4
6 12345
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Injection/Extraction
trajectory of stored beam
trajectory of incoming beam
preceding bunch
following bunch
emptyRF bucket
injection kicker
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Injection and extraction kickers
Technical subsystems
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Bending and focusing magnets
Dipole field for bending Quadrupole field for focusing
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Radiation damping stabilises the particle
particle trajectory
closed orbit
emitted photon
bending magnet
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Wiggler increases the radiation rate
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rf cavity replenishes the lost energy
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Interaction with beam pipe produces wake fields
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Scattering from residual gases cause instability
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Feedback systems stabilises the particles
single bunchshown atdifferent times
pick-up
amplifier
kicker
y
py
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Atom Ring by Georgia TechElectron ring in Oxfordshire
Relevance to Atom Ring
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Comparison of main features
• Similarities with the charged particle ring– Magnetic field can be used to guide the particles– Scattering from gas molecules shortens lifetime of particles– Same beam dynamics theory can be applied– Particles can be organised into bunches
• Differences in the atom ring– Energy is orders of magnitude smaller– No synchrotron radiation– Gravity effect is significant
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Atom Interferometry for Inertial Guidance
The ICE Cube, Institut d’Optique, France
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Some ideas for research and development
• Related activities around the world – Molecule storage rings, Netherlands: molecular experiments– ICE cube, France: inertial sensing project for space underway– Sagnac interferometer, Strathclyde: inertial sensing with atom ring– Atom chip interferometry, Imperial: precise control developed
• Ideas from accelerator physics– Strong focusing in all three dimensions for long term stability– Beam stability studies and feedback control systems– Energy source: The equivalence of an rf cavity?– Component ideas? Injectors, extractors, kickers, rings, focusing magnets– Presence of Intrabeam scattering, beam beam interactions?– Designing lines and lattices for atom transport and manipulation
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Linear Collider and the Atom Chip
The International Linear Collider
Atom Chip Interferometry at Imperial College
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