FFAG RF for muon
description
Transcript of FFAG RF for muon
2003/5/16 nufact-J 1
FFAG RF for muon
C. Ohmori
KEK
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Contents
• FFAG RF for 10-20 GeV muon– Parameters– Air-core system– Multi-feed scheme by Iwashita
• FFAG RF for PRISM
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FFAG RF for 10-20 GeV muon -RF parameters-
• Kinetic Energy : 10 => 20 GeV• Radius : 120 m (Circumference 754 m)• Longitudinal Emittance : 5 eVs• RF freqeucney : 18 or 24 MHz (Fixed Frequency)• Bucket Height : 10 GeV• : 0.003(Lattce 1), 0.002(Lattice 2)• Field Gradient 0.55-0.75 MV/m(average)• Cavity Length 1.6 m • Number of Cavity 120 (1 cavity/cell)• Gap Voltage : 1.8-2.43 MV• Beam Pipe : 360
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Lattice1 Lattice 2
T 18.2 21.2
0.003 0.002
frequency 24 MHz 18 MHz 24 MHz 18 MHz
H 60 45 60 45
Total Voltage 5.6 GV 4.2 GV 4.1 GV 3.1 GV
Average Field Gradient
0.75 MV/m
0.56 MV/m
0.55 MV/m
0.41 MV/m
# of turns 20 27?
RF Voltage for 2 X 5.4 GeV Bucket HeightHigh T is better for RF Voltage! But slow rotation.
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Design of High Gradient Cavity 1
-Air-core cavity-• Length 1.6 m /gap
• Outer Diameter : 2m
• Type of Cavity : Air –core
• Driven by a 150 kW class tetrode
• Driving Method: Loop Coupling
• Feeding : Direct or Co-axial line
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SUPERFISH Calculation(24MHz)
• Frequency : 24.03 MHz• Shunt Impedance: 3.53 M 2.2M/m• Q: 26400• Max. E field: 7.4MV/m 1.06Kilp. at 1 MV/
m• Lattice 1 (Low T)
– Max. E field : 12MV/m 1.7 Kilp. at 1.5 MV/m
• Lattice 2 (High T)– Max. E field : 8.3MV/m 1.2 Kilp. at 1.1 MV/m
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Design of Amplifier(24 MHz)• Load : • Vgap: 2.43 MV• 1 AMP per Cavity• Driven by 150 kW tube• Anode Voltage : 30kV• Peak Cathode Current: 120A (Max. 140 A) • RF Output Power: 0.84MW (duty < 0.16%)
• Operation : Class B• Cathode DC Current: 38 A (pea
k)
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Operation Line of Tube
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SUPERFISH Calculation(18MHz)
• Frequency : 18.16 MHz
• Shunt Impedance: 2.43 M 1.52 M/m
• Q: 23500• Max. E field: 10.6MV/m 1.65Kilp. at 1 MV/m• Lattice 1 (Low T)
– Max. E field : 12MV/m 1.85 Kilp. at 1.12 MV/m
• Lattice 2 (High T)– Max. E field : 8.7MV/m 1.35 Kilp. at 0.82 MV/m
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Design of Amplifier(18 MHz)• Load : • Vgap: 1.8 MV• 1 AMP per Cavity• Driven by 150 kW tube• Anode Voltage : 30kV (Max. 40kV)• Peak Cathode Current: 100A (Max. 140 A)• RF Output Power: 0.67MW (duty < 0.16%)
• Operation : Class B• Cathode DC Current: 30 A (pea
k)
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Air-core cavity • Superfish calculation seems OK (18 and 24
MHz systems), about 1.2 Kilp.
• Vacuum tube can deliver enough power.
• Many engineering issues – Large cavity (2m )– Driving method, loop coupling at low frequenc
y– Lifetime of tube: few 10000 hours => 15 tubes
(12%) will die in 6 months=> OK
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Design of High Gradient Cavity 2
-ferrite cavity-• Iwashita proposes a new approach, Multi-
Feed by Switching Devices.
• Type of Cavity : Ferrite cavity
• Driven by FET switch
• Driving Method: Loop Coupling
• Feeding : Multi-Feed
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PRISM RF
• MA (Magnetic Alloy) Cavity for high field gradient (-300kV/m) at 5MHz
• High Power operation of small vacuum tubes– 1 MW by 150 kW tubes
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MA Cavity• Will be used for JKJ synchrotron RF cavities• Characteristics of Magnetic Alloy
– Thin Tape , 18 m– High Field Gradient
• Voltage limit: Brf <Bsat. (1T) and Voltage per layer < 5 V
– High Curie Temperature– Large core, Rectangular Shape, (<4mX1.7m)– Large permeability(about 2000 at 5MHz)– Original Q value is small(0.6).– High Q is possible by cut core configuration– Thickness -35mm (50mm in future)
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High Gradient Cavity
1.00E+09
1.00E+10
1.00E+11
1 10 100 1000 10000
Brf[Gauss]
up'Q
fSY2
N5C
4M2-302
FT-small
FT-large
Magnetic Alloys
Ferrites
B=V/S=25kV/2pX5MHzX5cmX40cm=400GaussVlayer=25kV/(0.4mX0.7/18mm)=1.6V<5V(limit)
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MA Cavities
PoP FFAG CavityJKJ RF Cavity: 1.7m, 60kV, Cut CoreWater cooling, driven by 600kW tubes
KEK-PS MA Cavity: 90cm, 30kV, Cut CoreFluorinate Cooling
Himac Cavity: 50cm, 20kV, water cooling driven by 150kW tubes
5kV, CW, driven by 30kW tubes.
Barrier Bucket Cavity: 2.6m, 40kV, 6% duty, air cooling, driven by 30kW tubes installed in BNL AGS.
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Parameters of MA CavityPRISM
Power tube EIMAC 4CW150K
DC35-40kV900-kW(peak)
Field gradient 62.5- kV/cavity
250- kV/m
Gaps/cavity 1 gaps, 31.25-kV/gap, 25cm
Impedance 1k /gap 以上
# of cores 4 cores /gap ( 2.5- 3cmコア)
Cooling Air cooling
Barrier Cavity
EIMAC 4CW30K
~200kW(peak)
40 kV/cavity
15.3 kV/m
4 gaps, 10kV/gap
1k /gap
12 cores /gap
Air cooling(6%)
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MA core
MA core for 150MeV FFAG
1.7m X 0.985m X 30mm
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Summary• Conceptual Design for 10-20 GeV FFAG
RF system• Air-Core Cavity
• Ferrite Cavity using multi-feed
• High T is good for system design (-35% less voltage) but slow acceleration(35 % slower).
• Need a prototype system.
• System Design for PRISM RF is undergoing.