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.