GeV RCS
RCS at
at the
the JKJ
33 GeV
JKJ
Fumiaki Noda and JKJ Accelerator group
Fumiaki Noda and JKJ Accelerator group
Japan Atomic Energy Research Institute, Tokai, Naka, Ibaraki 319-1195, Japan
Japan Atomic Energy Research Institute, Tokai, Naka, Ibaraki 319-1195, Japan
Abstract.
(JKJ) is
is aa rapid
rapid cycling
cycling synchrotron
synchrotron designed
designed for
forhigh
highintensity
intensity
Abstract. 3GeV
3GeVRCS
RCS atat the
the JAERI-KEK
JAERI-KEK joint
joint project
project (JKJ)
proton
rate of
of 25
25 Hz.
Hz. In
In this
this paper,
paper, the
the outline
outline ofof3GeV
3GeV
protonbeam.
beam.The
The designed
designed output
output power
power is
is IMW
1MW with
with aa repetition
repetition rate
RCS,
of construction
construction are
are reported.
reported.
RCS,key
keyissues
issuestotoachieve
achievethe
the goal,
goal, R&D
R&D status
status and
and time
time schedule
schedule of
INTRODUCTION
INTRODUCTION
Japan
Japan Atomic
Atomic Energy
Energy Research
Research Institute
Institute (JAERI)
and
and High
High Energy
Energy Accelerator
Accelerator Research
Research Organization
(KEK)
(KEK) are
are proposed
proposed the
the joint
joint project
project for a high
intensity
intensity proton
proton accelerator
accelerator facility
facility [1-2]. The
accelerator complex
complex consists
consists of
of aa 0.4GeV
0.4GeV linac, a
accelerator
3GeVrapid-cycling
rapid-cycling synchrotron
synchrotron (RCS)
(RCS) and a 50GeV
3GeV
synchrotron (MR)
(MR) atat this
this facility.
facility. The
The major
synchrotron
requirement for
for the
the 3GeV
3GeV RCS
RCS isis IMW
1MW output
output beam
requirement
power. ItIt isis very
very important
important for
for 3GeV
3GeV RCS
RCS to control
power.
the beam
beam loss
loss and
and man/machine
man/machine protection
protection strategy
the
fromaaradiation.
radiation.
from
OUTLINE OF
OF 3GEV
3GEV RCS
OUTLINE
The 3GeV
3GeV Rapid-Cycling
Rapid-Cycling Synchrotron
Synchrotron (RCS)
(RCS) at
at
The
theJKJ
JKJwill
willhave
haveaathreefold
threefold symmetric
symmetric lattice.
lattice. Figure
Figure
the
shows the
the overview
overview of
of 3GeV
3GeV RSC.
RSC. Each
Each super11 shows
superperiod
consists
of
two
3-DOFO
modules
with
missing
period consists of two 3-DOFO modules with missing
bendsininarc
arcand
and3-DOFO
3-DOFOin
in insertion.
insertion. The
The arc
arc module
module
bends
has aa missing
missing bend
bend cell
cell for
for chromaticity
chromaticity correction
correction
has
magnets and
and longitudinal
longitudinal primary
primary collimator.
collimator. The
The
magnets
insertion
straights
are
used
for
the
injection
insertion straights are used for the injection
/collimation, the
the extraction
extraction and
and the
the RF
RF acceleration.
acceleration.
/collimation,
These
insertion
straights
are
dispersion
free. See
See
These insertion straights are dispersion free.
Reference
[3]
for
more
details
of
3GeV
RCS.
Reference [3] for more details of 3GeV RCS.
The main
main parameters
parameters are
are shown
shown in
in table
table 1.
1. The
The
The
injection
beam
energy
is
0.4GeV.
The
Hbeam
is
injection beam energy is 0.4GeV. The H- beam is
injected by charge exchange multi-turn injection
injected by charge exchange multi-turn injection
method and accelerated to 3GeV. The output beam
method and accelerated to 3GeV. The output beam
power is 1 MW with a repetition rate of 25 Hz. The
power is 1 MW with a repetition rate of 25 Hz. The
output beam is led to the spallation neutron and muon
output beam is led to the spallation neutron and muon
facility and the 50GeV MR.
facility and the 50GeV MR.
FIGURE
FIGURE 1.1. Schematic
Schematicview
viewofof3GeV
3GeVRCS
RCS
TABLE
TABLE 1.1. Main
Mainparameters
parametersofof3GeV
3GeVRCS
RCS
Parameter
Parameter
Circumference
Circumference
Injection
Injection Energy
Energy
Extraction
Extraction Energy
Energy
Extracted
Extracted beam
beam power
power
Particle
Particle Per
Per Pulse
Pulse
Revolution
Revolution Period
Period
at
at Injection/
Injection/ Extraction
Extraction
Repetition
Repetition Rate
Rate
Ramping
Ramping Pattern
Pattern
Injection
Injection period
period
Circulating Current
Circulating Current
at Injection/ Extraction
at Injection/ Extraction
Bunching Factor
Bunching Factor
at Injection
at Injection
Fundamental only
Fundamental only
with 2ndnd harmonics
with 2 harmonics
at Extraction
at Extraction
for 3GeV users
for 50GeV
3GeV users
for
ring
_____for 50GeV ring
value
value
348.333
348.333mm
0.4GeV
0.4GeV
3.0
3.0GeV
GeV
1MW
IMW
13
8.3
8.3xx10
1013
1.629
/1.196 µs
1.629/1.196
jis
25
Hz
25 Hz
Sinusoid
Sinusoid
~500 s
~500Ds
8.2 /11.1 A
8.2/11.1 A
0.3
0.3
0.4
0.4
0.2
0.2
0.3
0.3
KEY ISSUES OF 3GEV RCS
KEY ISSUES OF 3GEV RCS
In the design of 3GeV RCS, it is very important to
In theadesign
3GeV
it is verybeam
important
decrease
beam of
loss.
For RCS,
that purpose,
densityto
decrease a beam loss. For that purpose, beam density
CP642, High Intensity and High Brightness Hadron Beams: 20th ICFA Advanced Beam Dynamics Workshop on
High Intensity and High Brightness Hadron Beams, edited by W. Chou, Y. Mori, D. Neuffer, and J.-F. Ostiguy
© 2002 American Institute of Physics 0-7354-0097-0/02/$ 19.00
53
Large acceptance
acceptancefor
for transverse
transverse and
and longitudinal
longitudinal
Large
space
space
should
injection in
should be controlled by a painting injection
transverse and in longitudinal. These are effective
effective
methods to defusing a space charge force.
Simultaneously,
Simultaneously, it is need to control a beam loss
(localization)
(localization) and decrease an un-controllable beam
loss. An adequate aperture/collimator ratio is a matter
of importance for localization of beam loss. It is
necessary to keep the large acceptance for extraction
line, because the beam power at extraction energy
reaches to 1MW.
1MW.
and apertures
apertures are
are shown
shown in
in
The beam emittancce and
enlarged
Table 2. The beam emittance is intentionally enlarged
216π mm-mrad at the
the injection
injection by
by phase
phase space
space
to 216n
collimator acceptance
acceptance and
and
painting. On the other hand, collimator
324 and
and 486ft
486π mm-mrad,
mm-mrad,
physical aperture are 324
accept a maximum
maximum
respectively. The ring must also accept
±1 percentage.
beam momentum spread of ±1
Beam loss control
324π mmmmThe acceptance of extraction line is 324ft
ring collimator
collimator aperture.
aperture.
mrad. This value is equal to ring
Space-charge
force reduction
Space-charge force
Apertures
TABLE 2. Emittance and Apertures
The number of particles in the 3 GeV RCS is
is
13
8.3x10
ppp for 1MW output beam power. It is
8.3xl013
necessary to do painting injection with charge
exchange multi-turn injection for reduction of spacecharge force. The beam emittance is intentionally
n mm-mrad at the injection
enlarged to 216 π
injection by phase
space painting. Simultaneously, dual harmonic
space
acceleration system and longitudinal painting is
important issue for reduction of space-charge force. It
simple RF
makes a bunching factor larger than one of simple
system. We rely on that bunching factor is 0.4.
system.
Parameter
Transverse
Injection
Injection beam
Painting emittance
Collimator aperture
Physical aperture
Extraction aperture
Longitudinal (dp/p)
Injection
Injection
Collimator
value
value
π.mm-mrad
4 ft.mm-mrad
216 ft.mm-mrad
π.mm-mrad
324
324 ft.mm-mrad
π.mm-mrad
486
486 ft.mm-mrad
π.mm-mrad
324 ft.mm-mrad
π.mm-mrad
0.1%
0.1%
1%
1%
The incoherent space charge tune shift will be
about -0.15 by above treatments.
Other key issues
Reference [4-5]
[4-5] for more details of the design
See Reference
of painting injection system in transverse and
longitudinal phase space.
A damage of foil
foil cause directly beam loss.
Therefore,
Therefore, a long life
life and reliable charge
charge exchange
exchange foil
foil
and an auto-changer mechanism are
are developing
developing now.
now.
A prototype auto-changer was constructed
constructed already.
already.
Collimation system
Transverse and longitudinal collimation systems
are set in the 3GeV RCS. Collimator system consists
of primary collimator to scatter halo beam and
secondary collimator to collect the halo beam. The aim
secondary
of this collimator system is to localize the halo beam.
IW/m uncontrolled beam around the
It enable to keep 1W/m
ring. Transverse primary collimator and secondary
collimators set a dispersion free area. In addition,
longitudinal primary collimator sets the missing bend
area in arc module. This point has a large dispersion
and small beta function for transverse. Longitudinal
primary collimator is thinner than transverse one. So
scattered halo beam at the longitudinal primary
scattered
collimator passes through the arc section without beam
loss. The passed hallo beam is scatted by transverse
primary collimator again and is collimated by
transverse secondary collimators.
The large aperture bending magnet and quadrupole
quadrupole
magnet were constructed
constructed already
already and
and performed
performed the
the
many studies. In these magnets,
magnets, the
the coil
coil conductor
conductor isis
aluminum stranded conductor in order to
to reduce
reduce an
eddy current loss. See Reference
Reference [6] for more details.
For another magnets, correction magnet and kicker
kicker
magnets were constructed.
3GeV RCS is rapid cycling
cycling synchrotron,
synchrotron, so itit is
is
necessary to high gradient RF cavity. In 3GeV
3GeV RCS,
RCS,
the beam loading
loading is
is very
very heavy.
heavy. A
A leak
leak from
from RF
RF
bucket causes a beam loss
at
acceleration
loss at acceleration and
and
extraction. See Reference
Reference [7] for more details.
For vacuum chamber of rapid cycling synchrotron,
it is necessary to avoid any harmful
harmful effect
effect of the
the eddy
eddy
current. On the other hand, vacuum
chamber
vacuum chamber should
should
be treated the RF shield. Now
Now we have
have developed
developed long
long
and large aperture ceramic
ceramic chamber
chamber with
with RF
RF shield
shield
and TiN coating (inner surface)
surface) for bending
bending magnet.
magnet.
See Reference [8]
[8] for more details
54
Monitor system is also very important for the beam
diagnostic. A prototype beam position monitor was
constructed and performed the many studies.
SUMMARY AND
SCHEDULE OF 3GEV RCS
Beam loss limits the output beam power of
accelerator. Therefore, we
we should
should reduce the beam
loss and control the beam loss. In this paper, key
of the
the
issues are described from the point of view of
of 3GeV
3GeV RCS
RCS is
is in
in final
final
beam loss control. The design of
are
stage. Now fine-tuning and feedback from R&D are
of 3GeV
3GeV RCS,
RCS, see
see the
the
performed. For more details of
for High-Intensity Proton
Technical Design Report for
Accelerator Facility Project (Reference
(Reference [12]).
[12]).
BEAM LOSS ESTIMATION
Beam loss at the injection
It is important for H- injection to care the Lorentz
stripping loss and excited H0
HO beam loss. The magnetic
field of injection line is limited 0.55T. The Lorentz
10-6/m and total beam loss
stripping loss rate is about 10-6/m
is less than a few watts. Charge exchange efficiency
efficiency is
99.8%. The beam power of excited H
H°0 is about 0.4kW.
For the magnet passed through an excited H
H°0 beam, the
magnetic field set 0.2T between n=5 ad 6. Here n is
the excitation states level. Therefore, the
uncontrollable beam loss cause by excited H
H°0 is about
0
6W(n>6).
H° (n
(n<5)
H°0
6). The rest of excited H
5) is led to H
6W(n
beam dump, which designed 1kW
IkW capacity.
The construction of facility and production of
October, 2002
2002 arraignment
arraignment
instruments will start in October,
will start in April 2005. Moreover, the first beam of
3GeV RCS will be in October 2006.
REFERENCES
1. Imazato, J., “JHF
"JHF Physics”,
Physics", in these proceedings.
1.
"Accelerator Complex of
of Joint
Joint Project
Project in
in
2. Mori, Y., “Accelerator
Japan", in these proceedings
Japan”,
Beam loss during a acceleration
The beam tracking with apace-charge force using
Accsim, PATRASH and Simpsons codes are
performed. Preliminary estimations show the 3%
(4kW at injection) of beam are over the collimation
aperture (324 7i.mm-mrad).
π.mm-mrad). The detail tracking are
doing now. See Reference [9]
[9] for
for more details
details of
of beam
beam
tracking. In addition, beam tracking with fringe field
[10] for more details
are doing now. See Reference [10]
Shigaki, K.
K. et
et al.,
al., “The
"The JKJ Lattice”,
Lattice", in
in these
these
3. Shigaki,
proceedings.
L, et al,
al, “H
"H"- Painting
Painting Injection
Injection System
System for
for the
the JKJ
JKJ
4. Sakai, I.,
Synchrotron “,
", Proceedings
3-GeV High-Intensity Proton Synchrotron
ofEPAC2002
of
EPAC2002
"Longitudinal dynamics and
and rf hardware”,
hardware", in
5. Yoshii, M., “Longitudinal
these proceedings
"Design of aa Dipole Magnet for
for The 36. Tani, N., et al, “Design
of The
The JAERI/KEK
JAERI/KEK Joint
Joint
GeV Proton Synchrotron of
Project", Proceedings of EPAC2002
EPAC2002
Project“,
The beam collimator arrangement and the
collimation efficiency
efficiency are calculated by the STRUCT
code. The collimation efficiency
efficiency (≡beam
(=beam loss at the
collimator region/beam loss (4kW) is about 98%. The
rest of beam loss (about 80W)
SOW) is scattered around the
ring. See Reference [11]
[11] for more details of beam
collimation system.
al, “RF
"RF system
system for
for the 3-GeV Proton
7. Yamamoto. M., et al,
The JAERI/KEK
JAERI/KEK Joint
Joint Project“,
Project",
Synchrotron of The
EPAC2002
Proceedings of EPAC2002
et al,
al, “Vacuum
"Vacuum system
system design
design for
for the
the 3GeV3GeV8. Kinsho, M., et
joint project“,
project", J.
J. Vac.
Vac.
proton synchrotron of JAERI-KEK joint
p829-832
Sci. Technol. A20(3), May/Jun 2002, p829-832
9. Shimozaki, Y.
Y. et al.,
al., “HALO-FORMATION
"HALO-FORMATION AND
BEAM LOSS IN THE 3GEV RING OF THE JOINT
PROJECT”,
PROJECT", Proceedings of EPAC2002
EPAC2002
TABLE 3. Summary of beam loss estimation
Parameter
Injection line
Lorentz stripping loss
Injection area
Excited H
H°0
0
H beam dump
H°
Collimator area
Extraction area
Another area
value
10.
10. Molodojentsev,
Molodojentsev, A.,
A., “Tracking
"Tracking Studies
Studies for
for the
the JKJ
JKJ
Lattice”,
Lattice", in these proceedings.
<1W (un-control)/1kW*
(un-control)/lkW*
11.
11. Yamamoto, K., et al.,
al., “Beam
"Beam Collimator Design for
for The
3GeV Synchrotron of The JAERI-KEK Joint Project ”,
",
Proceedings of
of PAC
PAC ’01
'01 (2001).
(2001).
6W (un-control)/1kW*
(un-control)/lkW*
0.4kW (control)/1kW*
(control)/lkW*
4kW (control)/4kW*
~0
-0 (un-control) /1kW*
/IkW*
total about 80W
SOW
(un-control)
<1W/m
<lW/m
12.
12. Accelerator
Accelerator Technical
Technical Design
Design Report
Report for
for High-Intensity
High-Intensity
Proton Accelerator Facility Project, edited
edited by
by
Y.Yamazaki et al. January 2001.
*Upper value is a beam loss at normal operation.
Lower value is design value of building and components
55