Post on 16-Jan-2016
Y. Mori Kyoto/KEK
FFAG
C. OH
FFAG: Fixed Field Alternating GradientStrong focusing(AG focusing, phase
focusing)
• Like synchrotron, but fixed fieldMoving orbit(beam excursion)
• Like cyclotron, but not much.Zero chromaticity
• Constant phase advance/turn
• =Constant betatron tune
• No resonance crossing: Scaling FFAG
• cf. Non-scaling FFAG
Advantage of FFAGFast acceleration
DC magnetic field allows the beam acceleration only by RF pattern. No needs of synchronization between RF and magnets.
High average current with large repetition rate and modest number of particles in the ring
Space charge and collective effects are below threshold.
Large acceptanceTransverse (hor.)>10,000mm.mradLongitudinal dp/p>>10%
Ohkawa (1953), Kerst, Symon
MURA project e-model, induction acceleration ~’60s
No practical machine for 50years!
Problems : Magnet design, RF system
•World First Proton FFAG!
•-----> PoP FFAG @KEK, 2000
FFAG Accelerators :History
DifficultiesHadron(proton) Acceleration in
FFAG
•Need a new rf accelerating cavity.
•broad-band and high gradientParticle velocity changes in wide range.
Rooms for the rf cavity are limited in the ring because of its compactness and high super-periodicity.
•Need a non-linear(high gradient) field magnet.
•careful 3D design of magnetic field Zero chromaticity is very needed because momentum gain per turn is relatively small compared with that of electron.
World First Proton FFAG Accelerator
•PoP(proof-of-principle) FFAG :KEK 2000
Y. Mori and C. Ohkawa@FFAG01
Requirements of RF cavity
–Broad band
• Frequency sweep of a factor.
–High gradient
• Make it fast acceleration possible.
–Large aperture
• Especially in horizontal to accommodate orbit excursion.
–A few MHz to have large longitudinal acceptance
RF cavity with Magnetic Alloy has been developed at KEK for J-PARC cavity.
Field Gradient : 22.5 kV/m@1.7MHz (2 times lager than ordinary ferrite cavity).
MA core for RF cavity
• Wide aperture in horizontal, ~1m.
• Outer dimension is 1.7m x 0.985 m x 30 mm
Broad band : 1-10MHzHigh gradient : >50kV/m
FFAG Magnetscaling
Tapered gap• Gap(r) is proportional to 1/B(r)
• Easiest
• Fringe field has wrong sign.• g/r should be constant to have similar fringe
field effects
On-going project•150-MeV proton FFAG R&D : KEK
•Prototype model for various applications•FFAG for ADS : Kyoto Univ.
•FFAG + Sub Critical Reactor •Muon phase rotation PRISM : Osaka Univ.
•Muon Rare Decay (Mu-e conversion)Future project•Electron Model FFAG for muon : UK•FFAG for neutrino factory
•Neutron source for BNCT•Hadron therapy @ Ibaraki Prefecture•Electron source for sterilization
R&D Activities
Cavity assembly
• Number of cores 2~4• Outer size 1.7m x 1m• Inner size 1m x 0.23m• RF frequency 1.5 - 4.6 MHz• RF voltage 9 kV• RF output 55 kW• Power density 1 W/cm^3• Cooling water 70 L/min
Beam Acceleration
Beam acceleration is demonstrated. To increase the beam intensity, we used multi-turn injection and adiabatic capture.The adiabatic capture and beam acceleration were successfully carried out .
FFAG for ADSADSR in Kyoto University Research Reactor
Institute(KURRI)
Feasibility study of ADSR
•Accelerator Driven Sub-critical Reactor
Five-year program 2002 – 2006Subject
•Accelerator technology
•-variable energy FFAG
•Reactor technology
•-basic experiments for energy dependence of the reactor physics
FFAG – KUCA ADSR system schematic diagram
Ion source
injector FFAG
Main Ring
KUCA
Booster
FFAG
100keV 2.5MeV 20MeV 150MeV
injector FFAG
Acceleration & Extraction ! June 14th, 2005@injector FFAG (ion-beta)
injection extraction
Ia~0.25mA
Future project
•Neutrino factory : US-Study IIA, J-PARC
•Proton Driver (P>MW) for neutrino factory
Neutrino Factory
*Proton Driver*Target/Capture
*Muon Accelerator*Muon Storage Ring
E=20(50)GeV Δθ<1/(5-10)θ I>1 x 10**20 muon decays/year @one s.s
Neutrino beam
Types of FFAGScaling FFAG• Non-linear Magnetic Field
• “Constant Momentum Compaction” in longitudinal beam dynamics
• demonstrated - PoP-FFAG(KEK).
Non-scaling FFAG• Linear Magnetic Field in transverse
beam optics
• resonance crossing
• Strongly non-linear for longitudinal beam dynamics
• not demonstrated.
Edgecock
EMMAEMMAEMMAEMMA
• Scaled version of muon accelerator
• Flexible enough to learn about proton, carbon
• Parameters: - electrons - 10 to 20 MeV - 42 cells, doublet lattice - 37cm cell length - ~16m circumference - RF every other cell -
1.3GHz, TESLA frequency - magnets ~ 5cm x 2.5cm
• More details in next two talks!
FFAG ChainNeutrino Factory-J
PRISM-2
Neutrino Factory(step1)
Neutrino Factory(step2)
Proton DriverJ-PARC 50GeV proton accelerator complex Under construction/Completion March, 2008Beam Power ~1MW
Proton Driver with FFAG1.Rees(RAL)
•neutrino factory
•E=10GeV, P=4MW, 50Hz
•semi-scaling (non-scaling, non-linear)
2.Ruggiero(BNL)
•neutrino factory
•E=11.6GeV, P=18MW, 100Hz
•semi-scaling (non-scaling, non-linear)
3.Mori(Kyoto Univ.)
•ADS
•E=1GeV, P=1MW, 10kHz
•scaling (scaling, non-linear)
Non-scaling, Non-linear FFAGs
Categories for FFAG Lattice Cells of Five Magnets:
1. IFFAG: isochronous, no Qv=n and 2Qv=n crossing2. IFFAGI: IFFAG with combined function insertions3. NFFAG: non-isochronous, high/imag -t, no Q var’n
4. NFFAGI: NFFAG with insertions, some Qh variation
1 and 2: rapid acceleration of muons or electrons3 and 4 : high power proton drivers or medical rings
G. ReesG.
Classification of FFAG•Scaling FFAG(non-linear, constant tune,non-isochronous)
•MURA (e-model)
•PoP, 150 MeV, Kyoto (frequency sweep)
•Muon acceleration (Nufact-J, low frequency RF)
•Non-Scaling FFAG (Not yet build, Linear, non-constant tune, non-isochronous=asynchronous “gutter” acceleration)
•EMMA(U.K), muon acceleration(US design study IIA)
Semi-Scaling FFAG•Non-linear, Isochronous: Muon (RAL, CERN, Saclay)
•Non-linear, non-isochronous : Proton Driver (RAL, BNL,kyoto)
FFAG R&D Activities are mostly summarized.150-MeV FFAG accelerators operation
ADS in Kyoto Univ.
PRISM
Proton Driver (idea of semi-Scaling FFAG)
Neutrino factory
Scaling : demonstrated and works well.
Non-scaling : We need DEMONSTRATION!: EMMA
•We are in a very active phase of R&D!
Summary
Next FFAG workshop -> Osaka(KURRI)Dec. 2005 http://hadron.kek.jp/FFAG/