Development of a beam flattening
system at J-PARC/JSNS
1
Workshop on Non-linear beam expander systems in high-power
accelerator facilities
ISA, Department of Physics and Astronomy, Aarhus University, Aarhus,
Denmark 26th and 27th March 2012
(J-PARC/JAEA) Shin-ichiro MEIGO
2
Outline
Introduction
Present status of JSNS
Beam flattering system
Effect of miss alignment
Edge peak effect
Requirement of magnet located downstream
Beam peak reduction
3
Proton beam transport line
3-GeV RCS
Ne
utr
ino
lin
e
MLF
Neutron target
Muon target
road to coast
Length of BT: 314m
Ep: 3GeV
Power: 1MW
Rep.: 25Hz
JSNS MUSE
4
NMトンネル M1トンネル M2トンネル
QC10Q2260 LQ30120
QNQ1 QNQ2 QM1Q26100MIC
QM2Q26100MIC
QN1Q26100MIC
QN2Q26100MIC
QN3Q26100MIC
QN4Q26100MIC
Y20S2260AC
M20X20S2260AC
Y21S3060AC
M21X21S3060AC
Y22S2650MIC
M22X22S2650MIC
Y23S2650MIC
M23X23S2650MIC
QC11Q2260
QC12
P6
TMP 7
物質・生命実験施設
LQ30120 LQ30120
261500 314000B.W
ダクト径φ290
Muon Target
FCV3(DN200)
FCS(DN200)
QM1Q26100MIC
QM2Q26100MIC
proton beam window
neutron target
QM3Q26100MIC
QM4Q26100MIC
QM5Q26100MIC
QM6Q26100MIC
Y22S2650MIC
M22X22S2650MIC
Y23S2650MIC
M23X23S2650MIC
muon target collimators
16
00
ベースプレート
水銀ターゲット
ヘリウムベッセル
遮蔽(鉄)
ベッセルサポートシリンダー
反射体
遮蔽(重コンクリート)
アウターライナー
遮蔽(鉄)
遮蔽(コンクリート)
水素輸送管
水素減速材
遮蔽(鉄)
陽子ビーム
陽子ビーム窓
陽子ビーム窓メンテナンス用
ポート
ターゲット台車ベッセル内遮蔽体
P7 P8
垂直偏向部
直線部B
QA4
X05S2260AC
Y05S2260AC
M05
B1UD16150V
QA5
X06S2260AC
QV1Q2260
Y06S2260AC
M06
QV2Q2260
QV3Q2460
QV4Q2260
QV5Q2260
QV6Q2260
QV7Q2260
B1D
B16150V
QB1Q2260
QB2 QB3Q2260
QB4Q2260
QB5Q2260
QB6Q2260
X07S2260AC
Y07S2260AC
M07
X08S2260AC
X08S2260AC
M08
Y09S2260AC
X09S2260AC
M09 X10S2260AC
Y10S2260AC
M10 Y11S2260AC
M11X11S2260AC
Q2260 Q2260
Q2260P4
P3
Foil(DN200)
GV-man(DN200)
GV-man(DN200)
TMP(200 l/s)
水平偏向部 直線部C
QB7Q2260
BH1B16150
QH1Q2260
BH2B16150
QH2Q2260
QH3Q2260
QH4Q2260
QH5Q2260
BH3B16150
BH4B16150
QC2 QC3Q2260
QC4Q2260
QC5Q2260
QC6Q2260
QC7Q2260
QC8Q2260
QC9Q2260
QC1LQ30120
Y12S2260AC
X12S2260AC
M12 X13S2260AC
M13Y13S2260AC
Y14S2260AC
M14X14S2260AC
Y15S3060
M15X15S3060
Y16S2260AC
M16X16S2260AC
Y17S2260AC
M17X17S2260AC
Y18S2260AC
M18X18S2260AC
Y19S2260AC
M19X19S2260AC
LQ30120P5
GV3(DN200)
GV4(DN200)
QC9Q2260
QC10Q2260
← 3GeV RCS beam dump
horizontal bend
neutron
target
muon target
NM tunnel
QX1
SQ3060
X01S3060
QX2 QX3 QX4
Y01S3060
B01
D15150
QX6PB
PB13150
QX7
M01 X02S3060
Y02S3060
M02
QX8 DMP
D15150C11.8deg
QX9QX5 QX10
X03S3060
M03
B02
Y03S3060
QA1 QA2
X04S3060
Y04S3060
M04
QA3
SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060D16150
ダンプ入射P1
FCV1 & FCS1(DN200)P2
GV3(φ320)
GV2(φ320) GV1
(φ320)
proton beam
windowcollimators
pulse magnet to
50-GeV MR
B: 9 Q: 54 STR: 45
33m
Whole length 320m 600ns
FWHM ~150ns
Pulse
5
Proton beam at the target 3NBT・MLF beam operational status Beam study with 0.4 MWeq beam (Mar 2012)
1h demo of 0.3 MW beam ( Dec 2009)
User operation 0.2MW beam
Handling of high intensity proton beam Beam profile is important.
Pitting damage (P4 Law)
Profile measurement with high reliability
Condition of JSNS is harder than SNS SNS:60Hz, storage ring without muon target
JSNS:25Hz, RCS with muon target
- Target must be changed when pin holes was detected by the radiation monitor
Control of beam profile at JSNS becomes important
SNS has a record of exchanging new vessel within only 2 weeks after found fail.
In JSNS, failure of the vessel will take much longer time due to difficulties of handle of RI especially for release of tritium.
Peak reduction becomes very important!
Pin holes at target of SNS
Pin holes are permitted at
the inside wall of SNS but
not allowed at JSNS
Target vessel
SNS: 4 walls
JSNS: 3 walls
here
6
Diagnostics of beam profile and halo
Monitors at PBW Imaging Plate MWPM
Hot cell
IP
Target
Placed by RH
MWPM
Halo monitor
・SEC
・ TC
Beam profile monitor and beam halo monitor (online type)
Multi Wire Profile Monitors (MWPMs) (15 sets located) : SiC wires
At the proton beam window (PBW), MWPM located (1.8m from the target)
2D profile: Activation by the Imaging Plate (IP) (Offline type)
After beam operation: IP was attached at the target by the remote handling
TC
7
Beam behavior
0
10
20 Horizontal
0 100 200 3000
10
20
Beam direction position(m)
Beam
rm
s w
idth
(mm
)
Vertical
120 kW 300 kW
Good agreement with the design calculation
300kW:
eh,v 5.7, 4.9 p
120kW:
eh,v 2.7, 2.7 p
Result of RMS emittance Beam emittance and twiss parameters fitted by the observed
beam width
⇒ Good agreement in whole beam line
Consistence from the accelerator to the target.
0
10
20Horizontal
0 100 200 3000
10
20
Beam direction position(m)
Beam
rm
s w
idth
(mm
)
Vertical
300kW twiss parameter
ax -1.84, bx 20.4m
ay 0.57, by 5.26m
unit: mm mrad
e 5.4 p
ax -2.35, bx 24.8m
ay 0.89, by 5.88m
Twiss parameter at exit
of RCS
Calculation of 300 kW
case (by RCS team)
Residual dose at beam line:
Back ground except several points
8
Beam profile at the mercury target
2-D measurement by IP
Result by MWPM
Fitting by Gaussian
• Width of each pulse
obtained
• Beam width transformed to
the width at the target
-100 -50 0 50 1000
100
200
1st IP
Horizontal (mm)
Fit result Peak 1.35mm Sigma 23.8mm
Resultoffset= 01:Int.= 102.7961:Pos = 1.351151:Width=55.99872:Int.= 64.84372:Pos = -16.94012:Width=139.433
Profile result by the IP
• Fitted by two Gaussian curves
Contribution of primary protons and
secondary particles (mainly neutrons)
0.1 MW operation (2009 Dec) 0.2 MW operation (2010 Dec)
Obtained only 6 days of
cooling duration after
irradiation of 0.2 MW
beam
⇒ Possible for 1MW with
certain cooling time
MWPM at the PBW
9
Trend of beam width at the mercury target
2009 Apr
(Run#22)
2009 Nov
(Run#27)
2009 Dec
(Run#28)
2010 Jan
(Run#29)
2010 Dec
(Run#36
200kW)
sh sv sh sv sh sv sh sv sh sv
MWPM 17.3 10.3 22.8 11.0 24.4 11.7 33.8 16.6 54.3 22.6
IP 17.3 12.3 23.8 11.5 27.0 12.7 33.2 15.4 55.7 20.6
Both results by MWPM and IP show good agreement
• Demonstration of reliable method
• Reliable peak density can be obtained by MWPM in real time.
Unit: mm
To obtain low peak density, beam width
gradually expanded Comparison of experimental results
0
10
20
30
40
50
60
Run number
RM
S b
eam
wid
th(m
m) Horizontal
IP MWPM
Vertical IP MWPM
22 27 28 29 36
Found the higher activation at M23 than the estimation calculation, too much wide beam?
10
0 2 4 610-2
10-1
100
101
102
Sigma for V(cm)
Hea
t (W
/cc)
for
1M
W
Reflector Middle section
Reflectory=Σan x
n
a0=-1.37731862e+00
a1=1.57906223e+00
a2=-1.00184180e-01
2.00883063e-01
|r|=9.89000584e-01
Middley=Σan x
n
a0=-2.04023978e-01
a1=-2.42419803e-01
a2=4.15369844e-01
1.69400404e-01
|r|=9.98073455e-01
0 5 1010-2
10-1
100
101
102
Sigma for H(cm)
Hea
t (W
/cc)
for
1M
W
Reflector Middle section
Reflecty=Σan x
n
a0=-1.37747623e+00
a1=7.10670687e-01
a2=-2.02950615e-02
2.00813778e-01
|r|=9.89008212e-01
MiddSecy=Σan x
n
a0=-2.04156726e-01
a1=-1.09012246e-01
a2=8.41059968e-02
1.69345156e-01
|r|=9.98074713e-01
Conserve beam
aspect ratio
H:V=2.2:1
Heat deposition at vicinity<1W/cc
sh <37mm, sv <17mm
Target blade: no issues
Limit for 1MW operation without beam flattening
system.
Peak at the target: 14J/cc/pulse
-100 -80 -60 -40 -20 0 20 40 60 80 1000
5
10
15
Horizontal position (mm)
Q (
J/c
c/p
uls
e)
Heat loadlimit at bladeB
lad
e
Bla
de
1MW sh 37mmsv 17mm
Beam expand by linear optics
MWPM shows that the distribution is monotonous Gaussian.
Expanding Gaussian beam to decrease the peak density Vicinity of the target < 1W/cc(0.04J/cc/pulse)
Target blade < 90W/cc(3.5J/cc/pulse)
Beam halo was approximated to follow as monotonous Gaussian.
11
Beam halo measurements Heat deposition was measured by the thermo couples (TCs) located at the vicinity of the target and the beam window. Given by the temp rising due to beam irradiation Q(w/cc)=ρCdT/dt ρ:Density(g/cc), C: Thermal capacity (J/g/K), T:Temp (K),t: Time(s)
For beam of 200 and 300kW: Heat at vicinity ~0.3W/cc
Peak density and beam halo ⇒ Giving optimum parameter
Developed expert system for beam control (Beam orbit and profile)
Even a rookie can control the beam with confident as an expert.
Trend of temp at halo monitor at the PBW Result of heat deposition at halo monitor
12
Conceptual design of flattening Beam edge folding by non-linear optics
Linear optics Non-linear optics
w/ octupole
Phase space distribution (horizontal)
Beam flattening using octupoles
Present case is provably the first trial to the high intensity facility such as 1MW class.
Points: For the ideal system, octupole magnets (OCTs) can be placed at an
arbitrary position.
2 set of OCTs for flattening in horizontal and vertical directions
Increase the b function at OCTs within appropriate aperture Expand the beam width at each OCTs
Maximize beam aspect ration At horizontal OCT making large aspect ratio of H/V
Appropriate phase advance to the target
Peak edge appears contrary Beam offset cause the peak edge
S. Meigo, JAERI-Tech 2000-088
Where we should place OCTs? Location of OCTs: Preferable at near the mercury target (M2 tunnel)
-> Pragmatically very difficult High radiation and difficulty of precision alignment at M2 tunnel
Recent beam study shows that beam should be kept smaller in M2 due to the beam loss.
NMトンネル M1トンネル M2トンネル
QC10Q2260 LQ30120
QNQ1 QNQ2 QM1Q26100MIC
QM2Q26100MIC
QN1Q26100MIC
QN2Q26100MIC
QN3Q26100MIC
QN4Q26100MIC
Y20S2260AC
M20X20S2260AC
Y21S3060AC
M21X21S3060AC
Y22S2650MIC
M22X22S2650MIC
Y23S2650MIC
M23X23S2650MIC
QC11Q2260
QC12
P6
TMP 7
物質・生命実験施設
LQ30120 LQ30120
261500 314000B.W
ダクト径φ290
Muon Target
FCV3(DN200)
FCS(DN200)
QM1Q26100MIC
QM2Q26100MIC
proton beam window
neutron target
QM3Q26100MIC
QM4Q26100MIC
QM5Q26100MIC
QM6Q26100MIC
Y22S2650MIC
M22X22S2650MIC
Y23S2650MIC
M23X23S2650MIC
muon target collimators
16
00
ベースプレート
水銀ターゲット
ヘリウムベッセル
遮蔽(鉄)
ベッセルサポートシリンダー
反射体
遮蔽(重コンクリート)
アウターライナー
遮蔽(鉄)
遮蔽(コンクリート)
水素輸送管
水素減速材
遮蔽(鉄)
陽子ビーム
陽子ビーム窓
陽子ビーム窓メンテナンス用
ポート
ターゲット台車ベッセル内遮蔽体
P7 P8
垂直偏向部
直線部B
QA4
X05S2260AC
Y05S2260AC
M05
B1UD16150V
QA5
X06S2260AC
QV1Q2260
Y06S2260AC
M06
QV2Q2260
QV3Q2460
QV4Q2260
QV5Q2260
QV6Q2260
QV7Q2260
B1D
B16150V
QB1Q2260
QB2 QB3Q2260
QB4Q2260
QB5Q2260
QB6Q2260
X07S2260AC
Y07S2260AC
M07
X08S2260AC
X08S2260AC
M08
Y09S2260AC
X09S2260AC
M09 X10S2260AC
Y10S2260AC
M10 Y11S2260AC
M11X11S2260AC
Q2260 Q2260
Q2260P4
P3
Foil(DN200)
GV-man(DN200)
GV-man(DN200)
TMP(200 l/s)
水平偏向部 直線部C
QB7Q2260
BH1B16150
QH1Q2260
BH2B16150
QH2Q2260
QH3Q2260
QH4Q2260
QH5Q2260
BH3B16150
BH4B16150
QC2 QC3Q2260
QC4Q2260
QC5Q2260
QC6Q2260
QC7Q2260
QC8Q2260
QC9Q2260
QC1LQ30120
Y12S2260AC
X12S2260AC
M12 X13S2260AC
M13Y13S2260AC
Y14S2260AC
M14X14S2260AC
Y15S3060
M15X15S3060
Y16S2260AC
M16X16S2260AC
Y17S2260AC
M17X17S2260AC
Y18S2260AC
M18X18S2260AC
Y19S2260AC
M19X19S2260AC
LQ30120P5
GV3(DN200)
GV4(DN200)
QC9Q2260
QC10Q2260
← 3GeV RCS beam dump
horizontal bend
neutron
target
muon target
NM tunnel
QX1
SQ3060
X01S3060
QX2 QX3 QX4
Y01S3060
B01
D15150
QX6PB
PB13150
QX7
M01 X02S3060
Y02S3060
M02
QX8 DMP
D15150C11.8deg
QX9QX5 QX10
X03S3060
M03
B02
Y03S3060
QA1 QA2
X04S3060
Y04S3060
M04
QA3
SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060 SQ3060D16150
ダンプ入射P1
FCV1 & FCS1(DN200)P2
GV3(φ320)
GV2(φ320) GV1
(φ320)
proton beam
windowcollimators
pulse magnet to
50-GeV MR
M2
• Before beam commissioning, we hesitated to install octupole magnets. However, due to the following superiority of the J-PARC RCS・3NBT, we understand that the beam flattening by the octupole is possible.
- Very good stability of beam position - Deeply understanding of the beam optics
M1
15
Beam optics using OCT Flattening by the realistic magnet field of OCT(Koct), large beta function (b) at OCTs is necessary for the phase advance of f and RMS emittance e
Koct=1/eb2tanf
Large b makes difficult to have large beam acceptance
RCS collimator: 324pmm mrad (For b =100m -> 0.36m in diam)
From the preliminary result of the beam halo measurements, smaller acceptance than 324pmmmrad may be applicable.
Having large b at OCT1,2 -> Beam acceptance to be100 pmmmrad
Present beam optics Beam optics for flattening by OCTs
Large beta at OCT1,2
16
Octupole magnet
OCT1 and 2 will be installed at upstream of QC12, QNQ1.
at 3NBT tunnel and M1 tunnel
Q-O magnets distance is 1m
length of magnetic pole: 0.6m
Bore diameter 0.3m
Install new steering magnet: At downstream of QC12
OCT1 OCT2
M1 tunnel 3NBT tunnel
1m
OCT1 OCT2
1m
Horizontal view
Vertical view
Octupole magnet (800T/m3)
O3060(Width 1.2m, Length 0.6m, 6t)
Octupole magnets
Excellent of shape of the coil
Installation: Summer in 2013 during long shutdown
Field measurements Mapping by hole probe Field gradient 780 T/m3 @671A
Agreement with calculation
Confirmation agreement with design calculation
立会試験 2号機 励磁特性 0~800[A] 800~0[A],X=70,Y=0,Z=0[mm]
0
100
200
300
400
500
600
0 100 200 300 400 500 600 700 800 900
電流[A]
磁場
B
y[G
auss]
励磁特性 0~800[A] 励磁特性 800~0[A]
立会試験 2号機 X方向 -160~160[mm] 電流:671[A],Y=0,Z=0[mm]
-6000
-4000
-2000
0
2000
4000
6000
-200 -150 -100 -50 0 50 100 150 200
位置 X[mm]
磁場
By
[G
auss]
19
Simulation of the profile
DECAY-TURTLE (PSI version)
One of result ignoring the reality Ignore muon production target
Small acceptance of beam: 81p mm mrad
Using this optics let’s discuss the alignment error effect
W/O OCT W/ OCT
Achieved flat shape!
20
Alignment accuracy of octupole magnet
Beam offset at OCT 2mm in horizontal ->Edge peak appears Beam shift at OCT2(for horizontal): 2mm in horizontal
Increase about 8 % at the edge
Beam tuning for flattening system
Beam position monitor (BPM) is placed at each octupole magnets
Additional new steering magnets for horizontal and vertical
Beam center within 1 mm -> 4%
2D Profile at the target
21
Alignment of downstream magnets
Realignment of downstream magnets is quite difficult
Calculation: All magnets at M2 has 2 mm offset in horizontal.
Result: Betatron oscillation is found in the beam orbit, no influence on
the beam shape
⇒ No need realignment at M2
Horizontal Vertical 2D Profile at the target
Effect due to muon target
Phase space distribution distorted as Gaussian
Without scattering effect
Phase space distribution at muon production target
To minimize this effect
Focusing on the muon target as small as possible
Increase divergence ⇒ Smaller effect
With scattering effect
23
Beam profile with flattening system
Muon target: With muon target
RMS Beam emittance: 5p
Peak: 1.3Tp/cm2
9.4J/cc/pulse
Beam Loss: 80.8 kW
(mainly due to interaction at the
muon target)
Acceptance: Horizontal 114p
Vertical 111p
Reduction of peak 42 % of Gaussian
By P4 law: 0.68^4=0.2 (very small)
It is better to have larger beam acceptance at OCTs.
Profile at the mercury target Projection profiles on horizontal and vertical
axis compared with Gaussian
-8 -6 -4 -2102
103
104
Vertical (cm)
Gauss(sh 17mm) OCT (aug24#2)
-5 0 50
10000
20000
30000
40000
50000
60000
Vertical (cm)
Gauss( sh 17mm) OCT (aug24#2)
-20 -15 -10 -5102
103
104
Horizontal (cm)
Gauss(sh 37mm) OCT (aug24#2)
-20 -10 0 10 200
10000
20000
30000
40000
50000
Horizontal (cm)
Gauss(sh 37mm) OCT(aug24#2)
Closing up at vicinity
Beam study for octupoles optics
Revised OCT opt w/o MTG Previous OCT opt w/o MTG
Found slightly beam loss No significant beam loss for 0.18GeV inj
Phase space distribution RCS extraction beam
(0.4GeV injection)
Large aperture >250p
Required aperture ~250 p
Aperture ~100p
0 50 100 150 200 2501
10
100
1000
10000
Beam emittance (p mm mrad)
Be
am
lo
ss (
W)
at 1
MW
150pi painting w/ error
Beam acceptance (p mm mrad)
Beam profiles using flattening system
-20 -10 0 10 200
10000
20000
30000
40000
50000
Horizontal (cm)
Gaussian incld beam loss sh 37mm
H_DEC8_2.DAT
-5 0 50
10000
20000
30000
40000
50000
60000
Vertical (cm)
Gaussian incld beam loss sh 17mm
V_DEC8_2.DAT
Peak density ~11J/cc/pulse
Having larger aperture than 250 p mm mrad
26
0 200 400 600 800 10000
10
20
Beam power for 25Hz (kW)
Peak h
eat
den
sity
(J/c
c/p
uls
e)
JSNS 1MWDesign
Hp <1W/cc
SNS(at 0.3, 0.7 and 1 MW)
JSNS 2009 Dec 2010 Jan 2010 Feb 2010 Jun 2010 Dec
SNS 2MW Design
Peak heat density by flattening
• Even in the beam optics having
large beam acceptance such as 250
p, reduction of the peak enables by
the ~30% of Gaussian case.
• By the beam study, we can carry out
the beam flattening with the
appropriate the beam acceptance
which has beam loss < 1 W/m at the
OCT.
Beam power at 25 Hz (kW)
Beam
flattening
Beam power trend
27
0
1000
2000
3000
4000
5000
6000
2008/5/30
2008/6/22
2008/9/24
2008/12/10
2008/12/24
2009/1/25
2009/2/11
2009/2/19
2009/2/27
2009/6/1
2009/6/9
2009/6/17
2009/10/8
2009/10/18
2009/11/10
2009/11/18
2009/11/26
2009/12/13
2009/12/21
2010/1/13
2010/1/23
2010/1/31
2010/4/16
2010/5/11
2010/5/19
2010/5/27
2010/6/8
2010/6/16
2010/6/24
2010/10/19
2010/11/8
2010/11/16
2010/11/24
2010/12/2
2010/12/10
2010/12/18
2011/1/27
2011/2/4
2011/2/12
Beam
Pow
er[
kWh/D
ay]
0
50
100
150
200
250
300
350
400
450
500
Accum
ula
ted
Beam
Pow
er[
MW
h]
Beam
Pow
er[
kW@
25hz]
Beam Power[kWh/Day]
Accumulated Beam Power【MWh】
Beam Power[kW]
- 0.1-0.2 MW operation begun after earthquake.
- After installation He bubbler in the target, 0.3 MW operation will begin
High power with very high availability (~90%)
(/sr/pulse)
SNS(1MW) 4.2x1012
J-PARC/JSNS(0.3MW) 5.4x1012
Pulse neutron yield
28
Summary
Flattering system 30~40% of peak reduction
Due to scattering at the muon production target, makes difficult for flattening.
Focusing at the muon target is key at J-PARC/MLF
Beam acceptance is key issue of the system.
For 0.18GeV LINAC case, the case of 250 p mm mrad showed acceptable.
Octupole magnet Fabrication has been done
Good agreement with the magnetic field of design
Installation in summer 2013
29
Thank you for attention
- Note: Bulldogs have flat face
30
Y. Yuri et al., Phys rev special topics Accelerators and Beams 10, 104001 (2007)
K2n=(n-2)!(-1)n/2/(n/2-1)!(2eb)n/2-1btanf (n=4,6,8,10…) ⇒ Koct=1/eb2tanf, Kdodeca=-3/e2b3tanf
Settlement
Periodical survey for floor level
-14.0
-12.0
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
May-10 Jun-10 Aug-10 Sep-10 Nov-10 Jan-11 Feb-11 Apr-11 Jun-11 Jul-11 Sep-11 Nov-11 Dec-11 Feb-12 Apr-12
Date
Dis
plac
em
ent
(mm
)
RCS-03
S1
N1
N7
N81
N82
LM1-11
- Swing of 2mm observed at downstream
- Stable ??? Scheduled periodical beam adjustment is necessary.
RCS-03
EXPJ
EXPJ
S1
N1
N7 N81 N82
LM1-11
MLF
32
To MR To MLF
Kicker and septum
RCS
Beam orbit
3NBT Dump
Bending
B01 Pulse Bending
PB
Bending
B15U
Effect of residual field of pulse bending magnet
In every 80 pulses(3.2s) 4 pulses(K1-4): injected MR 74 pulses(K7-80): transport to MLF
Residual magnetic field distorts the beam orbit to MLF Measurement effect of residual field
Spatial distribution for K9 having kick angle
of 0.06 mrad by residual field (calculation) Beam profile for K9 pulse (0.06mrad)
By the pulse steering magnets
with slow response, possible
to compensate residual field
> 76 pulses can be utilized.
Time dependence of kick angle
by the residual field effect
0 1000 2000 30000
0.1
0.2
0.3
Elapsed Time after K4 pulse(ms)
Kic
k a
ngle
(m
rad)
y=exp(a + b x)a=-2.20276731e+00b=-3.20571963e-036.78503433e-02|r|=9.88279259e-01
Fitted after K7 Estimated by Magnetic Field
K5
2~3 pulses in every pulses
increases ~8 % at the edge
Pulse train K1 K2 K3 K4 K5 K6 K7 K8 K9 ... K80
Not used K7,8 delivered since Run#37
33
Residual field compensator
Orbit by compensation Response of field for compensation
for case1
Pulse steering magnet
Case1: 2 magnets at downstream
Case2: 2 magnets at upstream
Required kick angel
Case1: 0.3 mrad, Case2: 0.6 mrad