Transcript FFAG加速器の開発

FFAG
C. OHY. Mori Kyoto/KEK
FFAG: Fixed Field
Alternating Gradient
Strong focusing(AG focusing, phase
focusing)
Like synchrotron, but fixed field
Moving orbit(beam excursion)
Like cyclotron, but not much.
Zero chromaticity
Constant phase advance/turn
=Constant betatron tune
No resonance crossing: Scaling FFAG
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cf. Non-scaling FFAG
Advantage of FFAG
Fast 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 acceptance
Transverse (hor.)>10,000mm.mrad
Longitudinal dp/p>>10%
FFAG
Accelerators :History
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
Difficulties
Hadron(proton) Acceleration in FFAG
• Need a new rf accelerating cavity.
• broad-band and high gradient
Particle velocity changes in wide range.
Rooms for the rf cavity are limited in the ring
because of its compactness and high superperiodicity.
• 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
Y. Mori and C. Ohkawa@FFAG01
Proton FFAG Accelerator
• PoP(proof-of-principle)
2000
FFAG :KEK
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(2J-PARC
Field Gradient
: 22.5 kV/[email protected]
times lagercavity.
than ordinary ferrite
MA core for RF cavity
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Wide aperture in horizontal, ~1m.
Outer dimension is 1.7m x 0.985 m x 30 mm
Broad band : 1-10MHz
High gradient : >50kV/m
FFAG Magnet
scaling
Tapered gap
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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
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R&D
Activities
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
Cavity assembly
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Number of cores
Outer size
Inner size
RF frequency
RF voltage
RF output
Power density
Cooling water
2~4
1.7m x 1m
1m x 0.23m
1.5 - 4.6 MH
9 kV
55 kW
1 W/cm^3
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 ADS
ADSR in Kyoto University Research Reactor
Institute
(KURRI)
Feasibility study of ADSR
Accelerator Driven Sub-critical
Reactor
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Five-year program 2002 – 2006
Subject
Accelerator technology
-variable energy FFAG
Reactor technology
-basic experiments for energy
dependence of the reactor physics
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FFAG – KUCA ADSR system
schematic diagram
100keV 2.5MeV
20MeV
150MeV
Ion source
KUCA
injector FFAG
Booster
FFAG
Main Ring
injector FFAG
Acceleration & Extraction ! June 14th, 2005
@injector FFAG (ion-beta)
Ia~0.25mA
injection
extraction
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
Neutrino beam
Δθ<1/(5-10)θ
I>1 x 10**20 muon decays/year @one
s.s
Types of FFAG
Scaling FFAG
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Non-linear Magnetic Field
“Constant Momentum Compaction” in
longitudinal beam dynamics
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demonstrated - PoP-FFAG(KEK).
Non-scaling FFAG
• Linear Magnetic Field in transverse beam
optics
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resonance crossing
• Strongly non-linear for longitudinal beam
dynamics
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not demonstrated.
EMMA
EMMA
• Scaled version of muon accelerator
• Flexible enough to learn about proton, carbon
• Parameters:
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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!
Edgecock
FFAG Chain
Neutrino Factory-J
PRISM-2
Neutrino Factory
(step1)
Neutrino Factory
(step2)
Proton Driver
J-PARC 50GeV proton accelerator complex
Under construction/Completion March, 2008
Beam Power ~1MW
Proton Driver with FFAG
1. 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)
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Non-scaling, Non-linear FFAGs
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Categories for FFAG Lattice Cells of Five
Magnets:
• 1. IFFAG: isochronous, no Qv=n and 2Qv=n
crossing
• 2. IFFAGI: IFFAG with combined function
insertions
• 3. NFFAG: non-isochronous, high/imag -t, no Q
var’n
• 4. NFFAGI: NFFAG with insertions, some Qh
variation
G. ReesG.
Classification of FFAG
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Scaling FFAG(non-linear, constant tune,non-isochronous)
• MURA (e-model)
• PoP, 150 MeV, Kyoto (frequency sweep)
• Muon acceleration (Nufact-J, low frequency RF)
Semi-Scaling FFAG
•Non-linear, Isochronous: Muon (RAL, CERN, Saclay)
•Non-linear, non-isochronous : Proton Driver (RAL, BNL,kyoto)
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Non-Scaling FFAG (Not yet build, Linear, non-constant tune,
non-isochronous=asynchronous “gutter” acceleration)
• EMMA(U.K), muon acceleration(US design study IIA)
Summary
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!
Next FFAG workshop -> Osaka(KURRI)
Dec. 2005 http://hadron.kek.jp/FFAG/