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FFAG RF for muon. C. Ohmori KEK. Contents. FFAG RF for 10-20 GeV muon Parameters Air-core system Multi-feed scheme by Iwashita FFAG RF for PRISM. FFAG RF for 10-20 GeV muon - RF parameters-. Kinetic Energy : 10 => 20 GeV Radius : 120 m (Circumference 754 m)
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FFAG RF for muon C. Ohmori KEK nufact-J
Contents • FFAG RF for 10-20 GeV muon • Parameters • Air-core system • Multi-feed scheme by Iwashita • FFAG RF for PRISM nufact-J
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 • h : 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 f nufact-J
RF Voltage for 2 X 5.4 GeV Bucket Height High gT is better for RF Voltage! But slow rotation. nufact-J
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 nufact-J
SUPERFISH Calculation(24MHz) • Frequency : 24.03 MHz • Shunt Impedance: 3.53 MW 2.2MW/m • Q: 26400 • Max. E field: 7.4MV/m 1.06Kilp. at 1 MV/m • Lattice 1 (Low gT) • Max. E field : 12MV/m1.7 Kilp. at 1.5 MV/m • Lattice 2 (High gT) • Max. E field : 8.3MV/m1.2 Kilp. at 1.1 MV/m nufact-J
Design of Amplifier(24 MHz) • Load : 3.53 MW • 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 (peak) nufact-J
Operation Line of Tube nufact-J
SUPERFISH Calculation(18MHz) • Frequency : 18.16 MHz • Shunt Impedance: 2.43 MW 1.52 MW/m • Q: 23500 • Max. E field: 10.6MV/m 1.65Kilp. at 1 MV/m • Lattice 1 (Low gT) • Max. E field : 12MV/m1.85 Kilp. at 1.12 MV/m • Lattice 2 (High gT) • Max. E field : 8.7MV/m1.35 Kilp. at 0.82 MV/m nufact-J
Design of Amplifier(18 MHz) • Load : 2.43 MW • 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 (peak) nufact-J
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 f) • Driving method, loop coupling at low frequency • Lifetime of tube: few 10000 hours => 15 tubes (12%) will die in 6 months=> OK nufact-J
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 nufact-J
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 nufact-J
MACavity • Will be used for JKJ synchrotron RF cavities • Characteristics of Magnetic Alloy • Thin Tape , 18 mm • 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) nufact-J
High Gradient Cavity Ferrites Magnetic Alloys B=V/wS=25kV/2pX5MHzX5cmX40cm=400Gauss Vlayer=25kV/(0.4mX0.7/18mm)=1.6V<5V(limit) nufact-J
MA Cavities 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. KEK-PS MA Cavity: 90cm, 30kV, Cut Core Fluorinate Cooling JKJ RF Cavity: 1.7m, 60kV, Cut Core Water cooling, driven by 600kW tubes PoP FFAG Cavity nufact-J
Parameters of MA Cavity nufact-J
MA core for 150MeV FFAG 1.7m X 0.985m X 30mm MA core nufact-J
Summary • Conceptual Design for 10-20 GeV m FFAG RF system • Air-Core Cavity • Ferrite Cavity using multi-feed • High gT is good for system design (-35% less voltage) but slow acceleration(35 % slower). • Need a prototype system. • System Design for PRISM RF is undergoing. nufact-J