Introduction to FFAGs and a Non- Introduction to FFAGs and a Non- Scaling Model Scaling Model Rob Edgecock CCLRC Rob Edgecock CCLRC Rutherford Appleton Laboratory Rutherford Appleton Laboratory
Outline Outline EMMA EMMA • The FFAG principle • Brief history of FFAGs • Developments in Japan • Applications • Non-scaling FFAGs • Recent developments • Activities in UK/Europe • Conclusions
What is an FFAG? What is an FFAG? EMMA EMMA Fixed ixed F Field ield A Alternating lternating G Gradient accelerator radient accelerator F Magnetic field B = B 0 r 0 k r
What is an FFAG? What is an FFAG? EMMA EMMA Fixed magnetic field – – members of the members of the cyclotron cyclotron family family Fixed magnetic field Magnetic field variation B Fixed RF frequency (CW Frequency modulated ( θ ) operation) (pulsed beam) Uniform Classical Synchro- Alternating Sector-focused FFAG FFC + SC SFC FFAG
What is an FFAG? What is an FFAG? EMMA EMMA Fixed magnetic field – – members of the members of the cyclotron cyclotron family family Fixed magnetic field Magnetic field variation B Fixed RF frequency (CW Frequency modulated ( θ ) operation) (pulsed beam) Uniform Classical Synchro- Alternating Sector-focused FFAG Magnetic Alternative view: cyclotrons are just flutter special cases of FFAGs! FFAG Sector-focused cyclotrons Classical RF Synchro- cyclotrons swing cyclotrons
How do they work? How do they work? EMMA EMMA Magnetically: two types Radial sector FFAG Spiral sector FFAG
How do they work? How do they work? EMMA EMMA Horizontal tune † 2 ≈ 1 k To 1 st order: x dB av k r ≡ r where the average field index B av dr =〈 B 〉 B and av Note: • If B av increases with r then k > 0 Note: • If k > 0 then always horizontal focussing • The bigger k the stronger the focussing • Another reason for large k = p / L dp dL = k 1 † See Symon et al, Phys. Rev. 103 (1956) 1837 for derivation
How do they work? How do they work? EMMA EMMA Vertical tune † 2 2 ≈− k F 1 2tan To 1 st order: y 2 B F ≡〈 − 1 〉 where the magnetic flutter B av Note: • If k > 0 then vertical de-focussing Note: • Real ν y requires large F and/or ε • For radial sector, large F from reversed fields • Reverse fields increase average orbit radius B F • For spiral sector, large ε - no field flip + + - - - - B av 0 • More compact θ B D
A Brief History of FFAGs A Brief History of FFAGs EMMA EMMA • Invented in 1950s: Ohkawa in Japan, Symon in US Kolomensky in Russia • Interest, then and now, properties arising from FF & AG • Fixed Field: - fast cycling , limited (sometimes) only by RF - simpler, inexpensive power supplies - no eddy-current effects, cyclical coil stress - high acceptance - high intensity – pulsed and continuous - low beam loss and activation - easy maintenance - easy operation • Strong focussing: - magnetic ring - beam extraction at any energy - higher energies/ions possible
A Brief History of FFAGs A Brief History of FFAGs EMMA EMMA • 1950s/60s: most extensive work at MURA Chandrasekhar 20 to 400 keV Bohr machine Operated at MURA in 1956
A Brief History of FFAGs A Brief History of FFAGs EMMA EMMA • 1950s/60s: most extensive work at MURA Spiral sector machine Operated at MURA in 1957
A Brief History of FFAGs A Brief History of FFAGs EMMA EMMA • 1950s/60s: most extensive work at MURA 100keV to 50MeV machine Operated at MURA in 1961
A Brief History of FFAGs A Brief History of FFAGs EMMA EMMA • 1950s/60s: most extensive work at MURA • Proton proposals failed: technical complexity/energy 200MeV to 1.5GeV neutron spallation source Proposed by ANL in 1983
A Brief History of FFAGs A Brief History of FFAGs EMMA EMMA • Invented in 1950s: most extensive work at MURA • Proton proposals failed: technical complexity/energy • Re-invented late 1990’s in Japan for muon acceleration- ideal due to high acceptance & very rapid cycling - for a Neutrino Factory
A Brief History of FFAGs A Brief History of FFAGs EMMA EMMA • Invented in 1950s: 3 electron machines built, to 50 MeV • Proton proposals failed: technical complexity/energy • Re-invented late 1990’s in Japan for muon acceleration- ideal due to high acceptance & very rapid cycling - for a Neutrino Factory - first proton PoP FFAG built, 500 keV, 2000 - 2 nd proton FFAG, 150 MeV, 2003 - prototype for proton therapy
Innovations at KEK Innovations at KEK EMMA EMMA Two technological innovations made re-invention possible Two technological innovations made re-invention possible • FINEMET metallic alloy tuners: - rf modulation at >250Hz - high permeability → short cavities, high field - Q~1 → broadband operation • Triplet combined function magnets: - powered as a single unit - D’s act as return yokes - 3D computation codes for complex shapes
Scaling FFAGs Scaling FFAGs EMMA EMMA • Resonances big worry at MURA and in Japan
Scaling FFAGs Scaling FFAGs EMMA EMMA low ∆ E/turn • Resonances big worry at MURA and in Japan: • Maintain (in principle) fixed tunes, zero chromaticity 2 2 2 ≈− k F 1 2tan ≈ 1 k z x • Requires constant: field index magnetic flutter spiral angle • Gives: - same orbit shape at all energies - same optics “ “ “ “ • FFAGs with zero chromaticity are called scaling FFAGs B = B 0 r 0 k k=2.5 for POP r k=7.5 for 150 MeV FFAG
Under Development in Japan Under Development in Japan EMMA EMMA Properties of FFAGs have created a great deal of interest Properties of FFAGs have created a great deal of interest in Japan in Japan FFAGs built or being built E (MeV) Ion Radius (m) k Rep rate (Hz) Comments/1 st beam KEK PoP 1 p 0.8-1.1 2.5 2000 KEK – p therapy 150 p 4.5-5.2 7.5 2003 100 µ A KURRI – ADSR 200 p 4.54-5.12 7.6 1000 20 p 1.42-1.71 4.5 2.5 p 0.60-0.99 2.5 Spiral µ PRISM 20 6.5 5.0
ADSR ADSR EMMA EMMA • Accelerator Driven Sub-critical Reactor • Use thorium-232: 3x more than U, all burnt • Doesn’t make enough neutrons • Instead, neutron spallation: 10MW, 1GeV protons • Advantage: turn accelerator off, reactor stops! • Later stage: combine with transmutation • Only possible with linac or FFAGs • Test facility under construction in Kyoto
ADSR ADSR EMMA EMMA First beam this year
PRISM PRISM EMMA EMMA
Under Development in Japan Under Development in Japan EMMA EMMA FFAGs at design study phase E (MeV) Ion Radius (m) k Rep rate (Hz) Comments/1 st beam 0.1 µ A, spiral Ibaraki facility 230 p 2.2-4.1 20 MEICo - Laptop 1 e 0.02-0.03 0.8 1000 Spiral MEICo – Ion th. 400 C 6+ 7.0-7.5 12 0.5 Hybrid, spiral 7 C 4+ 1.4-1.8 0.7 0.5 Hybrid MEICo – p th. 230 p 0.0-0.7 2000 Superconducting, spiral NIRS Chiba 400 C 6+ 10.1-10.8 10.5 200 100 C 6+ 5.9-6.7 10.5 200 7 C 4+ 2.1-2.9 6.5 200 eFFAG 10 e 0.26-1.0 5000 20-100mA, spiral KURRI BNCT 10 p 1.5-1.6 >20mA µ Neutrino Factory 300-1000 20.75-21.25 50 1000 µ 1000-3000 79.77-80.23 190 1000 µ 3000-10000 89.75-90.25 220 1000 µ 10000-20000 199.75-200.25 280 1000
Under Development in Japan Under Development in Japan EMMA EMMA FFAGs at design study phase E (MeV) Ion Radius (m) k Rep rate (Hz) Comments/1 st beam 0.1 µ A, spiral Ibaraki facility 230 p 2.2-4.1 20 MEICo - Laptop 1 e 0.02-0.03 0.8 1000 Spiral MEICo – Ion th. 400 C 6+ 7.0-7.5 12 0.5 Hybrid, spiral 7 C 4+ 1.4-1.8 0.7 0.5 Hybrid MEICo – p th. 230 p 0.0-0.7 2000 Superconducting, spiral NIRS Chiba 400 C 6+ 10.1-10.8 10.5 200 100 C 6+ 5.9-6.7 10.5 200 7 C 4+ 2.1-2.9 6.5 200 eFFAG 10 e 0.26-1.0 5000 20-100mA, spiral KURRI BNCT 10 p 1.5-1.6 >20mA µ Neutrino Factory 300-1000 20.75-21.25 50 1000 µ 1000-3000 79.77-80.23 190 1000 µ 3000-10000 89.75-90.25 220 1000 µ 10000-20000 199.75-200.25 280 1000
Hadron Therapy Hadron Therapy EMMA EMMA Advantages over radiotherapy with X-rays Advantages over radiotherapy with X-rays Increasing clinical evidence of positive effects Stolen from Loma Linda of protons
Hadron Therapy Hadron Therapy EMMA EMMA Two main types of beam: Two main types of beam: • Protons: - most commonly used hadron - 230MeV for 30cm depth - cheaper/easier - advantages over X-rays - mainly cyclotrons • Carbon ions: - much better Radio Biological Effectiveness - less damage to healthy tissue than neon - 425MeV/u for 30cm - only synchrotrons - expensive! • Ideally, proton + carbon + other ions - best depends on tumour type and location
Hadron Therapy Hadron Therapy EMMA EMMA Two main types of beam delivery: Two main types of beam delivery: • 2D: Greater than necessary damage to healthy tissue
Hadron Therapy Hadron Therapy EMMA EMMA • 3D: - “range-stacking” + multi-leaf collimator - “spot”, “raster” or “pencil-beam” scanning
Recommend
More recommend
