2004/7/27 NUFACT04, RCNP, OSAKA 1
RF Construction for PRISM-FFAG
-Ultra High Field Gradient RF for Bunch Rotation@5MHz-
C. Ohmori
KEK
2004/7/27 NUFACT04, RCNP, OSAKA 2
Techniques to obtain a beam with low momentum spread
• Several ideas– Cooling in synchrotron – Barrier de-bunch in a synchrotron
– Linac Option
• Solution :
Bunch rotation in a FFAG !
•These techniques require 100ms-1s. •Short lifetime of beam
More R&D
2004/7/27 NUFACT04, RCNP, OSAKA 3
Bunch Rotation in Longitudinal Phase Space
Direction of Beam
Momentum
Injection to FFAG Large p/p
ApplyRF Voltage @ 5MHz
After several turns in FFAGSmall p/p
Saw Tooth RF is considered for smaller p/p
Low Frequency for Large Bucket vs. Difficulty to get High Voltage at Low Frequency
2004/7/27 NUFACT04, RCNP, OSAKA 4
Possible Scenarios to obtain High Voltage at 5 MHz
• Magnetic Alloy– High Field Gradient ( -200kV/m) might be possible by an
optimum design.
• Ferrite with High Q– Degradation of characteristics ?– Need R&D
• Ceramic Cavity– Very high field gradient might be possible.– Need R&D
2004/7/27 NUFACT04, RCNP, OSAKA 5
Magnetic Cores for Cavity
1.00E+09
1.00E+10
1.00E+11
1 10 100 1000 10000
Brf[Gauss]
up'Qf
Magnetic Alloys
Ferrites
Requirements for PRISMB=V/S=400Gauss
2004/7/27 NUFACT04, RCNP, OSAKA 6
MA Cavities
PoP FFAG Cavity in KEKJ-PARC RF Cavity: 1.7m, 60kV, Cut CoreWater cooling, driven by 600kW tubes
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.
2004/7/27 NUFACT04, RCNP, OSAKA 7
RF CavitiesField Gradient of Cavities for Proton
Synchrotrons Proton Synchrotron RF System
0
10
20
30
40
50
60
0 2 4 6 8 10 12
Frequency (MHz)
Field Gradient (kV/m)
SATUNE
MIMAS
CERN PSB
CERN PS
AGS
ISIS
KEK BSTR
KEK PS
JKJÅ@50GeV MR
JKJ Å@3GeV RCS
50GeV MR Upgrade
KEK-HGC
Ferrite Cavities
JKJ RF CavitiesKEK-PS MA Cavity
Proton Synchrotron RF System
0
50
100
150
200
250
0 2 4 6 8 10 12
Frequency (MHz)
Field Gradient (kV/m)
SATUNE
MIMAS
CERN PSB
CERN PS
AGS
ISIS
KEK BSTR
KEK PS
JKJÅ@50GeV MRJKJ Å@3GeV RCS 50GeV MR UpgradeKEK-HGC
PRISM
High Gap Voltage (X 3) & Short Cavity (X 2)Very High Gradient for very short moment (10s) !
2004/7/27 NUFACT04, RCNP, OSAKA 8
MA core for PRISM
1.7 m
2004/7/27 NUFACT04, RCNP, OSAKA 9
Parameters of MA CavityPower tube 4CW100,000E, DC 33-37kV,
1.5 MW(peak for 10s)
Field gradient 200- kV/cavity, -200kV/m
Gaps/cavity (3)-4 gaps, >50 kV/gap
Length 33cm/gap
Impedance 0.9k /gap,
# of cores 6 cores/gap (3.5cm core)
Size of core 1.7m X 1.0m (1 m X 0.3m aperture)
Cooling air cooling (Duty 0.1%)
2004/7/27 NUFACT04, RCNP, OSAKA 10
PRISM RF R&D • FY2003:
– Production of AMP, PS etc.
• FY2004: – AMP Commissioning
by a test cavity @ RCNP, Osaka-U.
– Design & production of 33 cm Cavity
AMP
Test Cavity
2004/7/27 NUFACT04, RCNP, OSAKA 11
RF system R&D
• 43 kVp/gap using 700 test cavity
• Design goal (60 A RF current) of AMP was achieved.
• 33 cm cavity will be >900 :
• Very compact design for AMP and APS.
RF voltage at the gap (red line)
2004/7/27 NUFACT04, RCNP, OSAKA 12
PRISM Cavity Design
• 1 Gap will be produced in this FY04.
APS
AMP
Cavity
By C. Ohmori, Y. Kuriyama
Beam Pipe
Side View
33cm
2004/7/27 NUFACT04, RCNP, OSAKA 13
Summary• R&D for PRISM RF has been started here,
(in M-Exp. Area, RCNP, Osaka-U).
• AMP, PS, D-AMP and MA Cores have been produced.
• AMP has been tested using a test cavity and achieved 43 kV at 5MHz.
• Test of Ultra High Field Gradient in FY2005
• Ultra High Field Gradient Cavity will be produced in FY2004.
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