Date post: | 21-Dec-2015 |
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What is an FFAG?
Like a synchrotron
Strong Focussing (‘Alternating Gradient’)
Dipole field increases with particle energy
But through path variation not time variation
B/t not dB/dt
Orbit changes with energy
RF changes slightly
For and against
Advantages Magnets do not cycle• Cheaper, simplerHigh Repetition rate• ~kHz rather than ~Hz High duty cycle• Not quite DC, but…Rapid acceleration• Limited by RF not magnet Large acceptance• Useful for protons, vital for
muons
Disadvantages Limited dynamic
rangeMagnets
complicatedLimited experienceAbandoned in
1950’s?
FFAG renaissance
• Improved Magnet and RF technology
• Materials, modelling
• Proton FFAG built and working in KEK, Japan
• Plans for proton, electron, muon FFAGs
The NS-FFAG
‘Scaling’: constant orbit shape
Gives constant betatron tuneAbandon scaling principle – lose control of
tune. Fall into resonance?
Argument
If the tune changes rapidly, resonances don’t have time to destroy the beam.
Rapid acceleration: Big turn-to-turn variationPlausible but needs verifyingAdvantages (if it works)• Very small (~zero) RF change needed• Simpler magnets (BR not ln B R) • Smaller beam pipe
EMMA
Proof of principle machine
10 to 20 MeV electrons
42 cells
~16m circumference
RF every other cell
1.3GHz, TESLA frequency
magnets ~ 5cm x 2.5cm
CF MagnetsCF MagnetsEMMAEMMA
Flux lines at maximum dipole and quadrupole currents. Dipole coil (blue),Quadrupole (red).
RF SystemRF SystemEMMAEMMA
1.3GHz ELBE-like RF Cavities
20cm slot length
Few 10-4 variation in frequency to
allow acceleration
mode changes
Low frequency system for
further resonance
crossing studies
Initial design and cost estimate
done
Bid to UK “Basic Technology” Programme
BASROC=British Accelerator Science, Radiation and Oncology Consortium
Request funding for
• EMMA construction (£3.8M + £1.8M)
• Design of proton R and D machine (PAMELA) (£0.8M)
• Applications from Archaeology to Zoology (£0.4M)
The Consortium
• CCLRC+Cockcroft – EMMA Construction
• Manchester/Cockcroft – Coordination
• Liverpool/Cockcroft – Magnets
• Oxford/John Adams – PAMELA design
• Oxford/Gray Cancer Institute + Birmingham + Imperial + Glasgow – PAMELA and Hadron therapy applications
• Surrey+Leeds – general applications
Plan
• Project start 1 April 2007, last 3.5 years• Build and study EMMA• Design and seek funding for PAMELA• Build up portfolio of FFAG applications
– Hadron therapy– Cell irradiation studies– Solar wind simulator– Accelerator Driven Thorium Reactors– Proton drivers for muon/neutron sources– Muon accelerator for neutrino factory
• Enlarge project through linked activities