1. RF System for Bunch Rotation C. Ohmori （ KEK)

2. Bunch Rotation in Longitudinal Phase Space Direction of Beam Momentum Injection to FFAG Large  p/p Apply RF Voltage @ 5MHz After several turns in FFAG Small  p/p Saw Tooth RF is considered for smaller  p/p Low Frequency for Large Bucketvs. Difficulty to get High Voltage at Low Frequency

3. Saw-tooth PRISM-low energy muon (68 MeV/c) => 200 kV/m ＠ 5 MHz Scaling FFAG for Neutrino Factory – high energy muon (200 MeV/c) Bunch Merging Scenario for muon collider

4. PRISM 200kV/m @ 5 MHz MA cavity X Tube AMP:1 k  X 60A/.33 m, 66kV/gap Core impedance : about 160  /core X 6 cores Tube AMP : OK, obtained >60 A as RF current –Optimum design for only pulse operation (duty <0.1%) –Tubes is operated with Class B for 10  s, other;Class C. –1 APS for 4 RF AMP. Tested with a test cavity and 43 kV/gap was obtained Saw-tooth RF is tested.

5. MA core for PRISM 1.7 m

6. PRISM Cavity Design APS AMP Cavity Beam Pipe Side View 33cm

7. PRISM But cost is expensive. cores >> AMP+PS And, prefer more voltage for more muons. 200kV/m => 300 kV/m Solution Improvement of Cavity (core) impedance Other approach: ceramic cavity

8. Improvements of cavity impedance Hybrid cavity with ceramic cavity Improvements of cavity cores –X 2 by annealing under magnetic field for thinner ribbon –Small cores : OK –Large core ?

9. How to improve MA consists of Fe, Si, B, Cu and Nb. Amorphous ribbon (<20  m) is annealed and crystallized. Combination of magnetic field during annealing and thinner ribbon (13  m) The small crystal has an axis magnetized easily. By the special annealing, the axis is equal. But relation between core impedance and this effect is not clear. Small cores : proved by Hitachi Metal Large core : need big magnet and special oven. => Appling FY2007 JSPS money to produce these special core in KEK. B-H curve of MA core produced by annealing with/without magnetic field. (by Hitachi Metal)

10. Ceramic Cavity Proposed by J. Griffin. Low frequency air core cavity with a ceramic capacitor to resonate. Titanium Oxide capacitor was tested. 50kVDC (tested with 60kVDC). 1200pF. Electrodes are O.D. 121mmX I.D. 52mm, Thickness of ceramic is 14mm. Supported by JSPS money. Purpose : bunch rotation with low rep. rate. Small test cavity :30 cm X 30cm 4 k , Q=700, fres=7 MHz High power test is planned. High rep. rate : Hybrid cavity system with MA cavity. –Effective Q => below 100.