Cosine-theta
configurations for
S.C. Dipole
Massimo Sorbi
on behalf of:
INFN LASA & Genova Team
Giovanni Bellomo, Pasquale Fabbricarore, Stefania Farinon, Vittorio Marinozzi, Massimo Sorbi, Giovanni Volpini
Eurocircol annual meeting,
Orsay, 19-20 November 2015
INTRODUCTION
We explored more configurations and conductors lay-out for cos-theta dipole.
Main constrains:
- Bore inner diameter
- Bore nominal field
- Operating temperature
- Nominal op. point on load line
- Strand max diam.
- Max strand N./cable
- Nominal insul. thick.
- Layer N. per cable type
- Yoke outer radius (single apert.)
- Field quality
- Fringing field (out of cryostat?)
50 mm
16 T
4.5 K
max 90% resp. to critical surf. ( T=1.7 K)
 1 mm
40
0.15 mm
2 (double pancake)
275 mm
b3,b5,…< 1 unit
<0.1 T
Additional preliminary constrains (to be confirmed):
• Collar thickness
30 mm
• Cu/S.C.
≥1
90%
100%
Conf. - INFN-1
2+2 layers
2 cable types:
N. Strand
Str. diam. (mm)
Cu/S.C.
Magnet characteristic:
cable1
28
1
1
cable2
32
0.7
1.5
•Op.Current 10700 A
•Coil out.rad. 80 mm
•Peak field 16.3 T (blc 3)
95.3 % load line @ 4.5 K
•Peak field 12.9 T (blc 6)
92.5 % load line @ 4.5 K
Turn n/quad.
Layer 1 15
Layer 2 24
Layer 3 34
Layer 4 33
NI/quad 1.13 MAt
Conf. - INFN-2
2+2 layers
2 cable types:
N. Strand
Str. diam. (mm)
Cu/S.C.
Magnet characteristic:
cable1
40
1
1
cable2
40
0.7
1.5
•Op.Current 12700 A
•Coil out.rad. 95 mm
•Peak field 16.2 T (blc 4)
91.5 % load line @ 4.5 K
•Peak field 12.6 T (blc 8)
90.7 % load line @ 4.5 K
Turn n.
Layer 1
Layer 2
Layer 3
Layer 4
14
22
33
37
NI/quad 1.35 MAt
Conf. - INFN-3
2+2 layers
2 cable types:
N. Strand
Str. diam. (mm)
Cu/S.C.
Magnet characteristic:
cable1
40
1
1
cable2
40
1
2.1
•Op.Current 12200 A
•Coil out.rad. 95 mm
•Peak field 16.2 T (blc 3)
91.4 % load line @ 4.5 K
•Peak field 12.1 T (blc 8)
87.5 % load line @ 4.5 K
Turn n.
Layer 1
Layer 2
Layer 3
Layer 4
17
29
33
40
NI/quad 1.45 MAt
Conf. - INFN-3
2+2 layers
Iron yoke external Radius = 400 mm (for single aperture)
Magnet characteristic:
Conf. - INFN-4
2+2+2 layers
•Op.Current 5251 A
•Coil out.rad. 88 mm
3 cable types:
N. Strand
Str. diam. (mm)
Cu/S.C.
cable1
20
1
1
cable2
38
0.53
1.27
cable3
38
0.53
2.1
Weight av.: 1.76
•Peak field 16.2 T (blc 3)
88.5 % load line @ 4.5 K
•Peak field 14.02 T (blc 9)
90.0 % load line @ 4.5 K
•Peak field 12.79 T (blc 11)
90.0 % load line @ 4.5 K
Turn n.
Layer 1
Layer 2
Layer 3
Layer 4
Layer 5
Layer 6
16
21
36
49
57
65
NI/quad 1.28 MAt
Summary of configurations:
Common parameters:
• Single bore dipole
• Bore diam.
• Collar thick.
• Yoke out. rad.
Type
Cable
str. N.
Str.diam.
(mm)
50 mm
30 mm
275 mm
Cu/S.C. Rcoil-out. Current Operating point
(mm)
(kA)
on load line (%)
Tot.
Energy
L
En./cond strand NI
(MJ/m) (mH/m) (J/mm3) area (MAt)
(mm2)
4 layers
INFN-1
28
32
1
0.7
1
1.5
80
10.7
95.3
92.5
(lay.1)
(lay.3)
1.22
21
0.18
6730
2.26
4 layers
INFN-2
40
40
1
0.7
1
1.5
95
12.7
91.5
90.7
(lay.1)
(lay.3)
1.77
21
0.20
8834
2.7
4 layers
INFN-3
40
24
20
38
38
1
1
1
0.53
0.53
1
2.1
1
1.27
2.1
95
12.2
22
0.15
11285 2.90
5.25
(lay.1)
(lay.3)
(lay.1)
(lay.3)
(lay.5)
1.71
88
91.4
87.5
88.5
90.0
90.0
1.42
102
0.15
9244
6 layers
INFN-4
2.56
Consideration on inductance/current for quench protection:
• For a magnet with energy extraction (dumping resistance) it is preferable to have low
inductance and large current (the current constant time is L/Rd)
• For magnet with negligible energy extraction (our case) the requirement of low
inductance and large current does not appear necessary (the current constant time is
L/Ri with both L ÷ N2 and Ri ÷ N2 )
• It may be harder to induce fast transition on internal layers  solutions may be interlayer heaters or CLIQ
Other considerations:
• The configuration of 6 layers has additional construction complication (1 more splice
for cable connections) and construction cost (1 more double pancake)
• The vantage is reduced dimension for cable ( easier for winding), easier cable
“packing” in winding, more critical temperature margin, more control of field quality
Two-in-one layout
Preliminary considerations for the cross talking:
• The bore field increases 0.9 T (6%)  current can be decreased 6%
• The operating margin increase 1% 
• Quadrupole harmonic appear 10-20 unit  not hard to correct (iron
machining/holes, asymmetric positioning of conductor)
Fringing field consideration
• The target of 0.1 T is reached at about 400-450 mm from the yoke outer radius=275
mm for single aperture  outside of the cryostat
• In the double aperture the 0.1 T is reached at about 150-200 mm yoke outer
radius=400 mm  now very close outside of the cryostat
Single aperture
Yoke ext. R=275 mm
Double aperture
Yoke ext. R=400 mm
Conclusions:
• The space of possible configurations has been explored
• With the 2+2 layers configurations the target of 90% operating point on load
line is almost reached (actually reached for the double aperture)
• With the 2+2+2 layers configuration the target is reached
• The required field quality can be reached
• The explored configurations have to be optimized for construction reliability
(conductor positioning, angles, etc.)
• The mechanical analysis has to confirm the thickness of collars (now 30 mm)
• Protection studies will have to confirm the choice for Cu/S.C. ratio
• The passage to double aperture is not challenging from the magnetic point of
view  we can focus on single aperture design