Design of DC septum magnets based on measurements and 3D calculation of
an R&D septum magnet
for Rapid Cycle Synchrotron of J-PARC
Masao Watanabe,
Accelerator Group, JAERI
J-PARC overview RCS and the septum magnets overview
Comparison of measurements and
3D calculation of an R&D septum magnet 3D calculation of RCS septum magnets
Outline
Overview of J-PARC
181MeV (400MeV)
RCS and Septum magnets
Injection
Dump
Extraction
3 Septum magnets
2 Septum magnets
2 Septum magnetsCircumference: 348m
3 GeV(B=12.8Tm)
181 MeV(B=2.03Tm)
Septum magnets of RCS are required for
7 Septum magnets [2(injetion) 、 3(extaction) 、 2(dump)],
large aperture for low losses of high intensity beam (1 MW),
high durability to minimize the maintenance after the high activation.
RF acceleration
Design parameters of septum magnets
Injection Dump Extraction
Unit SEPI-1 SEPI-2SEPD-
1SEPD-
2SEPE-
1SEPE-
2SEPE-
3R&D(SEPE-
3)
number of magnets
1 1 1 1 1 1 1 1
max. field T 0.487 0.439 0.501 1.086 0.695 1.402 1.659 1.13
effective length mm 1400 800 1000 1000 900 1000 1000 1000
gap width mm 370 348 368 622 336 521 743 760
gap height mm 136 136 136 140 223 189 166 142
wave form DC environment Air (not in vacuum) septum thickness mm 87 45 51 340 34 90 260 185
material of core Electromagnetic soft iron (JIS SUYP-1; block) excitation current A 6246 5650 6787 5603 11176 12312 11035 12800(MAX)
turn number of coils
turn 8 8 8 24 10 16 20 10
max. voltage of coil
V 20 14 19 53 33 28 17 10
cooling of coils Water
J-PARC overview RCS and the septum magnets overview
Comparison of measurements and
3D calculation of an R&D septum magnet 3D calculation of RCS septum magnets
Outline
Schematic diagram of the R&D septum magnet
Upper view
Side view (without edge shield)
90097 163
4040
1010
SUS tickness
Mag
net
ic s
hie
ld t
ick
ne
ss(S
oft
-iro
n b
loc
k)
Magnetic shield tickness (Silicon steel sheet:0.5tmm*20)
Mag
net
ic s
hie
ld t
ick
ne
ss(S
oft
-iro
n b
loc
k)
1022
142
760
1200
Coil(Copper bar):10turn Core(Soft-iron block)
440
Photographs of the septum magnet and the measurement
Septum magnet
Hall device probe
3D stageDC power supply
Photograph of the coil inside the shield
Ceramic is employed against the high radiation for the electronic insulation of the coils.
Schematic diagram of cross section of the gap
OPERA3D modelWhole view Core and coil
Coil (2 turns)Magnetic Shield (Silicon steel)
Core (soft-iron)
Magnetic Shield (soft-iron)Core (soft-iron)
(1/2 model)
Comparison of measurements and 3D calculation
S(mm)
S(mm)
Leakage field was not agreed.
Field distribution (By) at X=0
Magnetic field in the gap was agreed.
90097 163
4040
1010
Magnetic shield
Core
Coil
Magnetic field in the gap.
Leakage field.
X(mm)
Leakage field distribution (By) at X=-334mm(Distance of 18mm from the septum shield)
-1.2 104-1 104-8000
-6000
-4000
-2000
0
2000
-150 -100 -50 0 50 100 150
By(Gauss)
S(cm)
MeasurementCalculation
Why?-150
-100
-50
0
50
100
-150 -100 -50 0 50 100 150
By(Gauss)
S(cm)
Edge shieldposition
Calculation
Measurement
Upper view
BH curves
1.6 104
1.62 104
1.64 104
1.66 104
40 50 60 70 80 90 100
By(Gauss)
X(cm)
Calculation 2
Calculation 1
Effects of BH curves near the saturation
Leakage field distribution (By) at X=-334mm
-150
-100
-50
0
50
100
-150 -100 -50 0 50 100 150
By(Gauss)
S(cm)
Calculation 2
Calculation 1
Measurement
Edge shieldposition
0
0.5
1
1.5
2
0 5000 1 104 1.5 104 2 104
H(A/m)
B(T
)
Calculation 1 (Catalog data)
Calculation 2 (The near lower limit of the standard)
Near saturation
-1.5 104-1 104-5000
0
5000
1 1041.5 1042 104
-50 -25 0 25 50 75 100
By(Gauss)
X(cm)
Calculation 2Calculation 1
Field distribution (By) on the median plane at S=0
Schematic diagram of the core
Cross sectional area of the bolt holes are
only 0.17% of the one of the return yoke.
Effects of the bolt holes near the saturation
Leakage field distribution (By) at X=-334mm
Distribution of B on the surface of the core
-150
-100
-50
0
50
100
-150 -100 -50 0 50 100 150
By(Gauss)
S(cm)
Calculation 2
Calculation 3
Measurement
Edge shieldposition
0
5000
1 104
1.5 104
2 104
-50 -40 -30 -20 -10 0 10 20 30 40 50
|B|(Gauss)
S(cm)Edge of the yoke Edge of the yoke
Distribution of B near the surface (Y=500mm) at center of the bolt holes
440mm:Return yoke thickness
33:Bolt holes
900m
m
0.014T
2.24T
Effects of the bolt holes near the saturation 2
1.6 104
1.65 104
1.7 104
1.75 104
-40 -20 0 20 40
|B|(Gauss)
S(cm)Edge of the yoke Edge of the yoke
Distribution of B near the surface (Y=500mm) at center of the bolt holes
Distribution of B on the surface of the core
0.014T
2.24T
we have to operate the core in the low magnetic field region which means the permeability is high enough. Our standard is 1.5 Tesla in maximum to be operated.
Attention points in design of RCS septum magnets
1.To suppress the leakage field,
When we operate not only the shield but also the return yoke at near saturation region.
2. When we cannot to obtain the shield or the yoke thickness enough,
(by weight limit, space limit and so on)
we have to take into account effects of dispersion of BH curves and bolt holes.
Design parameters of septum magnets
Injection Dump Extraction
Unit SEPI-1 SEPI-2SEPD-
1SEPD-
2SEPE-
1SEPE-
2SEPE-
3R&D(SEPE-
3)
number of magnets
1 1 1 1 1 1 1 1
max. field T 0.487 0.439 0.501 1.086 0.695 1.402 1.659 1.13
effective length mm 1400 800 1000 1000 900 1000 1000 1000
gap width mm 370 348 368 622 336 521 743 760
gap height mm 136 136 136 140 223 189 166 142
wave form DC environment Air (not in vacuum) septum thickness mm 87 45 51 340 34 90 260 185
material of core Electromagnetic soft iron (JIS SUYP-1; block) excitation current A 6246 5650 6787 5603 11176 12312 11035 12800(MAX)
turn number of coils
turn 8 8 8 24 10 16 20 10
max. voltage of coil
V 20 14 19 53 33 28 17 10
cooling of coils Water
Schematic diagram of the third extraction septum magnet
Side view (without edge shield) Upper view
100 100900
160
40
Ma
gn
eti
c s
hie
ld t
ickn
ess
(So
ft-i
ron
blo
ck
)
771.5742.5
1514
77
1.5
16
6
17
09
30
40
45
0
38
0
The gap between the coil has 1 mm slope.
Core(Soft-iron block)
Mag
net
ic s
hie
ld t
ickn
es
s(S
oft
-iro
n b
loc
k)
Coil(Copper bar):20turn
SUS tickness
Schematic diagram of extraction septum magnets
232.5
3.96°
51.6
3.1
61. 4
9. 55°
471.2
4
45
1.74°
141.5
Extraction septum 3
Extraction septum 2
Extraction septum 1
OPERA3D modelWhole view Core and coil
Coil (2 turns) Core (soft-iron)Magnetic Shield (soft-iron)
Core (soft-iron)
BH curves of soft iron
Field distribution (By) on the median plane
2D calculation and effects of BH curve
0
0.5
1
1.5
2
0 5000 1 104 1.5 104 2 104
H(A/m)
B(T
)
Calculation 1 (Catalog data)
Calculation 2 (The near lower limit of the standard)
-2 104-1.5 104-1 104-5000
0
5000
1 1041.5 104
-50 0 50 100 150
By(Gauss)
X(cm)
Calculation 2
Calculation 1
Not saturated in the shield
3SEPE3.3
F:\MASAO\MYDOCU~1\FILE\SUPERF~1\RFBUNC~1\3SEPE3~1.AM 2-27-2005 3:25:40
0
20
40
60
80
100
120
140
0
20
40
60
80
100
120
140
-60 -40 -20 0 20 40 60 80 100 120
More than 1.5T region.
Leakage field of the extraction septum 3
-5
-4
-3
-2
-1
0
1
-300-250-200-150-100 -50 0 50 100 150
By(Gauss)
S(cm)
End of the shield
Center of the core
Leakage field distribution (By) at the central orbit on the RCS
OPERA3D model
Central orbit on the RCS
BH curves of soft iron
0
0.5
1
1.5
2
0 5000 1 104 1.5 104 2 104
H(A/m)B
(T)
Calculation 1 (Catalog data)
Calculation 2 (The near lower limit of the standard)
Magnetic fields of an R&D septum magnet were measured and calculated by OPERA3D (TOSCA).The core was operate in high magnetic field region. This means the permeability is low. Leakage fields depended on not only the dispersion of BH curves but also bolt holes to fasten the return yoke.We obtained a standard ; the core should be excited less than 1.5 Tesla.On the basis of the results of the R&D magnet, the third extraction septum magnet was designed. The magnetic field in the core and the leakage field were estimated.
Conclusions
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