Target Magnets & Shielding
Bob WeggelParticle Beam Lasers, Inc.
Magnet Optimization Research Engineering, LLC.March 5, 2012
1
Isometric View of Three Target‐Magnet Designs
Design IDS120h (top), IDS120i (middle) & IDS120j (bottom) [courtesy Van Graves]
2
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
3
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.
4
Isometric View of Meshed Shielding Vessels of IDS120h
5
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.
6
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]
Sag
of s
uppo
rt tu
be w
ith 2
00 G
Pa
You
ng's
mod
ulus
[m
m]
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.
7
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
of s
hiel
ding
ves
sel w
ith 2
00 G
Pa
You
ng's
mod
ulus
[m
m]
500
1000
2000
200
300
400
600
800
1200
1600
5 6 7 8 9 10 11 12 13 14 15 16
10 K 9 K 8 K 7 K 6 K 5 K 4.2 K
Ambient field [T]
Nb 3Sn
-stra
nd n
on-c
oppe
r cur
rent
den
sity
[A
/mm
2 ]
Field and Temperature Dependence of Current Density of Nb3Sn Strands
8
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
Radius ratio O.D./I.D.
Fiel
d ra
tio
B
2/B1
9
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 error103(B)2/B
Desired fieldTotal field
SC magnet
Resistive magnet
Distance along axis [cm]
On-
axis
fiel
d [T
]
10
-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
11
-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) -
Bz(z
,0)
[T]
Bz(z,r) - Bz(z,0) of Off-Axis Field of Target Magnet IDS120j
12
Field Magnitude |B| ≡ (Br2+Bz2)½ of Target Magnet IDS120j
Maximum field = 20.4 T; contours at 1.5 T and integer values from 1 T through 20 T
13
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%.
14
σhoop in Copper & Nb3Sn Magnets (Most‐Upstream Cryostat)
Maximum hoop strain in each coil is 0.35%; contour interval = 0.02%.
15
σhoop in Coils of Cryostat #2 (NbTi Conductor)
Maximum hoop strain in each coil is 0.35%; contour interval = 0.02%.
16
σhoop in in Coils of Cryostat #3 (NbTi Conductor)
Maximum hoop strain in each coil is 0.35%.
17
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.
18
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.
19
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 error103(B)2/B
Desired fieldTotal field
SC magnet
Resistive magnet
Distance along axis [cm]
On-
axis
fiel
d [T
]
20