150 MeV FFAG

1
150 MeV FFAG

• T. Adachi, M. Aiba, K. Kikuchi, K. Koba, S.
  Machida, Y. Mori,
• R. Muramatsu, A. Muto, C. Ohomori, T. Sakae, I.
  Sakai,
• Y. Sato, M. Sugaya, T. Shibata, A. Takagi, R.
  Ueno,
• T. Yokoi, Y. Yonemura, M. Yoshii, M. Yoshimoto,
• Y. Yuasa and Joe Nakano
• - 150MeV FFAG group -
• June 6, 2003
• Nu Fact_at_Columbia Univ. NY

2
Contents

• Present status of 150MeV FFAG Accelerator
• Introduction of FFAG
• Schematic drawing of 150 MeV FFAG
• Parameter
• Magnet, RF, etc

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Introduction - Characteristics of FFAG

• Fixed Field flexibility, easy operation,
  large beam current, low power consumption
• FFAG magnetic Field BB0(r0/r)k
• Satisfying the cardinal condition,
  zerochromaticity Scaling FFAG
• High repetition rate
• Super conducting magnet
• Alternating Gradient Accelerator
• strong focusing, down sizing
• Compact size ( cf. Cyclotron)
• Large Horizontal acceptance
• wide aperture
• Large momentum acceptance
• FFAG has characteristics becoming to the large
  intensity proton driver and the manipulator of
  secondary beam PRISM, Muon Accelerator.
• The design of Neutrino factory, Japanese group
  proposes, based on scaling FFAG ring.

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Introduction-150 MeV FFAG project

• FFAG was proposed by Ohkawa, Symon and
  Kolomensky. (50s)
• An electron FFAG at MURA project in the 50s
• PoP FFAG the first proton FFAG in the world
  
• In June 2000, Our PoP FFAG accelerated the proton
  beam successfully.
• confirming the acceleration can be done in
  1msec.
• 150 MeV FFAG project the second proton FFAG
  
• The project to construct a practical machine was
  started.
• feasibility study for scaled-up FFAG Accelerator
• ex.) Construction of large FFAG ring
• Fabrication of Yoke-Free Magnet and large
  aperture RF system
• Demonstrating the beam acceleration and
  extraction in high reputation rate
• Establishment of injection and (FAST) extraction
  scheme

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150MeV FFAG Schematic view
KEK-PS East Counter Hall
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FFAG Schematicview
Beam Dump
P.S. FFAG magnet
RF
Straight Chamber
Beam profile monitor
Ext. B-Septum
Cyclotron
Bump magnet
Beam transport
FFAG Magnet
B-Septum
P.S. for Ext. B-Septum
FFAG Control Room
Current Monitor (CT)
E-Septum
Kicker magnet
Kicker power supply
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Cyclotron
Mag. Septum
Bump
Beam transport
Mag. Septum
Bump
E-Septum
Kicker magnet
150 MeV FFAG ??????
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150MeV FFAG Parameter
Cyclotron Parameters
Energy 12MeV Field 1.69T Current(full)
25µA RF Freq. 50Mhz Dee Voltage pulse
width 160µsec_at_250Hz Extraction Current
0.5µA (Current in Cyclotron 2µA) ( Deflector
loss 1.5µA)
Dee Voltage with Gate pulse
80µsec
160µsec
4msec
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150 MeV FFAG scaling FFAG

• 150 MeV FFAG is a scaling FFAG.

Tune vs. mean radius
BL-F/D ratio vs. radius
excursion
Tune diagram
Design satisfy the zero-chromaticity.
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150 MeV FFAG - Return Yoke Free Magnet

• Return Yoke Free Magnet The return yoke of
  Focusing sector is removed.

Deviation between Measurement and TOSCA design
is within 0.3 in flat field area.
FF B in F Sector FD B in D Sector FS B in Shunt
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Alignment of the maget
We aligned the magnets within the precision of
0.2 mm.
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Cyclotron(Injector) and Beam transport

• Cyclotron
• 10 MeV proton beam
• 250Hz pulse operation
• Max. extraction current 0.5µA

• Transport
• 2 sets of steeringtriplet Q mag.

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Beam Injection Study

• 10MeV(137MeV/c) proton Injection Study with
  Magnetic and Electric Septum

Magnetic field 1T for 10MeV proton ?450mm
E35kV/cm Deflecting angle 80mrad Distance
between electrode 22mm
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Beam Injection Study
With Magnetic and Electric Septum
we are studying the beam orbit in detail, and
installing the bump magnets for the beam
acceleration
150 MeV FFAG ??????
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RF system

• Large Magnetic Alloy (FINEMET) Cavity
• Number of core 4 pieces
• Outer (Inner) size 1700x950mm(980x230mm)
• Core thickness 25mm
• RF frequency 1.5 4.6 MHz
• RF voltage 9kV
• RF output 55kW
• Power density 1W/cm3
• Cooling water 70 L/min

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Summary

• We finish the construction of 150 MeV FFAG ring,
  and starting the beam study.
• We observed the circulating beam of one turn with
  Faraday Cup with Magnetic and Electric Septum on.
• the next ..
• We are now studying the injection beam orbit in
  detail, to confirm the FFAG ring satisfying our
  design.
• After installing a set of bump magnets, beam
  acceleration will be started.

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150 MeV FFAG The design of the magnet pole

• The design of the edge of
• the F-sector pole

• The final design of the poles

w/o patch
with patch
Magnetic field in the center of sectors
BL
BL-F/D ratio vs. radius
A comparison of Magnetic field in the focusing
sector
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FFAG Magnet alignment
????????? ??10????????????? ???????
2m 10?0.000048 ? 0.1mm???????
?????????
COD?????0.5mm??????????0.2mm??????????????
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Measurement of Magnetic field
Alignment error 0.2mm
All area of half cell, where the beam pass
through, is covered by moving the measurement
bench.
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Calibration of FFAG magnet
Measured field with various F D current
Coil F 50 turn D 5 turn
Design (125MeV mode) F 910A / D 780A
Trimmed F 883.7A / D 1042.3
Measured field magnitude (not shape) deviates a
little from design value.
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150 MeV FFAG - Measurements of magnetic field.
Measurements of magnetic field with hole probe.
Discrepancy (?B/B)
Y
The discrepancy between any two magnets is 0.3
at most. The alignment error of hole probe
explained that discrepancy.
Y-3545cm 5cm step
X
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Simple Comparison to TOSCA(after current
trimming)
dB/B (measured-TOSCA)/TOSCA
Deviation between Measurement and TOSCA is
within 0.3 in flat field area.
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Discrepancy between any Magnets
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150MeV FFAG Schedule