target magnets & shielding bob weggel particle beam lasers, inc. magnet optimization research...
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Target Magnets & Shielding
Bob WeggelParticle Beam Lasers, Inc.
Magnet Optimization Research Engineering, LLC.March 5, 2012
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Isometric View of Three Target-Magnet Designs
Design IDS120h (top), IDS120i (middle) & IDS120j (bottom) [courtesy Van Graves]
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Cross Sections of Target-Magnet Designs [courtesy Van Graves]
IDS120h: I.R.’s step down gradually from 120 cm to 45 cm; minimal gaps between coils IDS120i: Large gaps between cryostats; I.R.’s = [120, 100, 80, 60] cm; gaps at [3, 9, 15] mIDS120j: 3 coils per cryostat; I.R.’s = [120, 90, 70, 50] cm; gaps at [4,10,15] m; zmax = 20 m
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Cross section of Coils & Shielding Vessels of IDS120h
Tubes & flanges: = 7.85 g/cm3; shielding = 10 g/cm3; Outer ≈ 30 tons/m; Inner ≈ 8 tons/m.
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Isometric View of Meshed Shielding Vessels of IDS120h
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Sag of Shielding Vessel vs. Length L & Wall Thickness t
O.R.max = 114 cm; I.R.min = 60 cm; γ = 7.85 g/cm3; γshielding = 10 g/cm3; tin = ½tout; ~30 tons/m.
With tout = 4 cm, tin = 2 cm & L = [6, 7, 8, 9] m, sagFEM = [1.5, 2.5, 4.1, 6.4] mm Limit L to 8 m.
1
2
5
10
5 6 7 8 9
FEM
2-cm outer wall
2.5 cm
5 cm
4 cm
3 cm
Length of support tube [m]
Sa
g o
f su
pp
ort
tu
be
with
20
0 G
Pa
Yo
un
g's
mo
du
lus
[m
m]
Sag of Coaxial-Tube Beam: 1.14-m rmax
, 0.60-m rmin
; Tubes = 7.85 g/cm3; Annulus = 10 g/cm3
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Sag of Shielding Vessel vs. Length L & Wall Thickness t
O.R.max= 58 cm; I.R. min = 16 cm; tout = 4 cm; tin = 2 cm; γ = 7.85 g/cm3; γshielding = 10 g/cm3;
~8 tons/m. When L = [6, 6½, 7, 7½, 8] m, sag = [2.0, 2.9, 4.0, 5.4, 8.0] mm Limit L to 7 m.
2
3
4
5
6
7
6.0 6.5 7.0 7.5 8.0
FEM4-cm outer wall,2-cm inner wall
Length of shielding vessel [m]
Sag o
f sh
ield
ing v
ess
el w
ith 2
00 G
Pa Y
oung's
modulu
s [m
m]
Sag of Inner Shielding Vessel of IDS120h
8
500
1000
2000
200
300
400
600
800
1200
1600
5 6 7 8 9 10 11 12 13 14 15 16
Bob Weggel 5/9/2011
10 K 9 K 8 K 7 K 6 K 5 K 4.2 K
Ambient field [T]
Nb
3S
n-s
tra
nd
no
n-c
op
pe
r cu
rre
nt
de
nsi
ty
[A/m
m2]
Field and Temperature Dependence of Current Density of Nb3Sn Strands
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Normalized Maximum Hoop Stress σ* ≡ σmax / (B1 j1 a1)
a1 ≡ I.R. of coil; a2 ≡ O.R. of coil; B1 ≡ B(r=a1), B2 ≡ B(r=a2); j1 ≡ current density
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
3.53.02.52.01.51.0
Bob Weggel 5/8/2011
Radius ratio O.D./I.D.
Fie
ld r
atio
B2/B
1
Normalized Maximum Hoop Stress * max.
/(B1 j
1 a
1)
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On-Axis Field Profile B(z)of Target Magnet IDS120j
<B(z)> = 20 T over the 75-cm length centered at z = −37.5 cm. B(z=15 m) ≈ 1.5 T.
0.5
1
2
10
5
20
-450 -300 -150 0 150 300 450 600 750 900 1050 1200 1350 1500-75
Field error
103(B)2/B
Desired fieldTotal field
SC magnet
Resistive magnet
Distance along axis [cm]
On-a
xis
field
[T]
On-Axis Field Profile of Target Magnet "IDS120j"
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-0.45
-0.40
-0.35
-0.30
-0.25
-0.20
-0.15
-0.10
-0.05
0
0.05
0.10
0.15
0.20
0.25
0.30
0.35
-450 -300 -150 0 150 300 450 600 750 900 1050 1200 1350 1500-75
r = 5 cmr = 10 cmr = 15 cmr = 20 cmr = 25 cmr = 30 cm
Distance from plane z = 0 [cm]
Rad
ial c
ompo
nent
of m
agne
tic fi
eld
[T]
Radial Component of Off-Axis Field of Target Magnet IDS120j
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-0.08
-0.07
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
-450 -300 -150 0 150 300 450 600 750 900 1050 1200 1350 1500-75
5 cm10 cm15 cm20 cm25 cm30 cm
Distance from plane z = 0 [cm]
Bz(z
,r)
- B
z(z,0
) [
T]
Bz(z,r) - B
z(z,0) of Off-Axis Field of Target Magnet IDS120j
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Field Magnitude |B| ≡ (Br2+Bz
2)½ of Target Magnet IDS120j
Maximum field = 20.4 T; contours at 1.5 T and integer values from 1 T through 20 T
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Hoop Strain σhoop in Magnet of Copper Hollow Conductor
700-MPa coil banding limits σhoop in each coil to 0.35%; contour interval = 0.02%.
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σhoop in Copper & Nb3Sn Magnets (Most-Upstream Cryostat)
Maximum hoop strain in each coil is 0.35%; contour interval = 0.02%.
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σhoop in Coils of Cryostat #2 (NbTi Conductor)
Maximum hoop strain in each coil is 0.35%; contour interval = 0.02%.
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σhoop in in Coils of Cryostat #3 (NbTi Conductor)
Maximum hoop strain in each coil is 0.35%.
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σhoop in Coils of Cryostat #4 (NbTi Conductor)
Maximum hoop strain in two upstream coils = 0.35%; max.(σhoop) in downstream coil also is 0.35% if one adds an identical set of coils downstream.
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Target Magnet “DS120j5”: Optimized I.R. of Flanking Coils
I.R.’s of coils in cryostats #2-#4 are [120, 90, 116] cm, [76, 70, 75] cm & [67, 50, 67] cm.
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On-Axis Field Profile B(z)of Target Magnet IDS120j5
Maximum field error is nearly 30% less than in design IDS120j.
0.5
1
2
10
5
20
-450 -300 -150 0 150 300 450 600 750 900 1050 1200 1350 1500-75
Field error
103(B)
2/B
Desired fieldTotal field
SC magnet
Resistive magnet
Distance along axis [cm]
On-
axis
fiel
d [T
]On-Axis Field Profile of Target Magnet IDS120j5