Superconducting Solenoids for COMET
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Transcript of Superconducting Solenoids for COMET
Superconducting Solenoidsfor COMET
KEK Cryogenics Center, Osaka Univ. Kuno-san’s
Team,J-PARC MLF Muon Group
Layout of Beam Line Magnets
• Pion Capture– High Field– High Radiation
• Transport & Decay – Medium Field– Curved solenoid
• Experiment– Low Field– Large volume– Curved solenoid
Pion Capture Solenoid
Requirement• High Field
– More pion to capture– More (better) conductor– Larger stored energy
• High Radiation – High Power Beam– Heat Load– Radiation Damage
Big SC Solenoids in Real World
Heat Load~1WCost~1M$
Heat Load~10kWCost~100M$
MRI MagnetsField: 1~4TCooling: He Free?
Detector SolenoidsField: 1~4T (NbTi)Cooling: IndirectAl Stabilized CableWith Cooling pipes
Fusion (ITER CS model)Field: ~13T (Nb3Sn)Cooling: DirectCable in Conduit
Heat Load~100WCost~10M$
Technology ChoiceConductor Material
1. NbTi (~5T) choice for now 1. Well established2. Not Expensive
2. Nb3Sn or Nb3Al (~12T)1. Established for solenoids2. Expensive (x5:conductor, x2:assebly to NbTi)
3. High Tc (~20T??)1. Not established for high field magnets2. Very expensive
Technology ChoiceHeat Load
• 50GeV x 15A – Beam: 750kW– Coil: ~100W– Cable in Conduit?
• 8GeV x 7A
– Beam: 56kW– Coil: ~10W– Detector Solenoid
Mostly Common Feature
•Aluminum stabilized cable
•quench stability•quench protection•transparency
•Indirect cooling with cooling pipe
•2 phase forced flow•Thermo siphon
•Technology well established
•Many solenoids are in use•Familiar to people in high energy physics
•Good for field up to ~5T•4T already achieved
•Good Solution for near future plan
•With modest budget
Detector Solenoids
ATLAS MEC MEC
B0 [T] 2 5 6
Bpeak [T] 2.3 5.3 6.4
I [A] 7730 11100 6800
Coil Layer 1 2 4
Rinn [mm] 1250 500 500
Length [mm] 5300 1400 1400
Support-Cyl [mm] 12 10 10
Conductor Width [mm] 4.25 (4.5) 4.7 (5) 4.7 (5)
Hight [mm] 30 30 30
Jcond [A/mm2] 61 80 49
Strand Diameter [mm] 1.28 1.28
Number 32 32
Total CrossSection
41.1 41.1
NbTi/Cu/Al 1/1.1/5.0 1/1.1/5.0
JNbTi [A/mm2] 566 347
LoadLineRatio 0.63 0.71
Bc [T] 8.4 9.1
Jc [A/mm2] 889 476
General M [ton] 0.988 1.94
E [MJ] 12.26 19.3
E/M [kJ/kg] 12.5 9.9
σh [MPa] 93.8 83.2
σeq [MPa] 113 97.8
σeq/σ0.2 0.77 0.67
Capture Solenoid Design
5mm
30mm
Load Line (5-30-2Layers)
0
500
1000
1500
2000
2500
3000
0 1 2 3 4 5 6 7 8 9 10
B [T]
Jc [A/mm
2]
4.2K
5.0K
6.0K7.0K
6.08K
5.41K
Jc = -591*B+5854
Temperature Margin
Indirect cooling
Cooling path from conductor to cooling pipei.e. Temp. gradient
We choose 5T versionMore temp margin2 < 4 layer (transparency)Lower peak field
Quench Protection
0
5
10
15
0.1 1 10 100 1000 104
WASABESS
CMD-2
D0
ZEUS
VENUS
TOPAZ
CLEO-IIBABAR
CDF
BELLEDELPHI
ALEPHH1
SDC-proto
ATLAS-CS (2 T)
CMS (4 T)under construction
BessP-Proto
Stored energy (MJ)
BessP (1 .05T)
M-E conversion
QuenchStored energypartly extractedpartly into coil
To protect coilspread heat evenly
Still there are limitParameter to lookStored Energy toCoil Mass Ratio
Yield Strength VS RRR
0
50
100
150
200
0 500 1000 1500 2000
Residual Resistivity Ratio
Ni 20000-ppm
Zn 200-ppm
Ni 1000-ppm
(20%)
(20%)
(20%)
(0 %)
(0 %) (0 %)
(+)
Cu
Good RRR: for quench stability and protection
High Yield Strength: for high EM force
High Yield Strength Al stabilized Conductor R&D
• For High Energy Physics– Higher Field : > 5 Tesla– Larger Size : Diameter 〜 10m
• Combination of Various Technology
– ATLAS Al Ni Alloy• Ni-0.5 ~ 1 %
– CMS-Hybrid Support • A6058 -->> A7020
Y.S.(0.2%) = 400 MPaRRR = ~ 400
13
An R&D Work using ATLAS-CS Conductor + A6061-T6
• T.S. is > 50 % reinforced with A6061using Electron Beam, and Laser Beam Welding
• LBW may be a potential technology EBW, LBW
Laser Beam Welding
Refrigerator
• Cryocoolers (GM or pulse tube) may not be strong enough
• Maybe Helium refrigerator plant needed
Guideline for magnet design
• Optimize the magnetic field design below 6 T – As base-line, using NbTi superconductor
• (with a future option for > 10 T Nb3Sn, Nb3Al magnet for the pion capture solenoid)
• Apply “thin solenoid” design concept with Al-stabilized superconductor and indirect-cooling to– Minimize radiation heating, – Refer technology established at,
• ATLAS, BESS, and CMS Solenoid
Toward Higher Field
• Al-stabilized Nb3Sn/Nb3Al Solenoid beyond 10 T
• An R&D may be proposed in cooperation with NIFS.
Toward Higher Beam Power
• Cable in conduit– Removal of large heat load– ITER CSExperiencedby modelNb3Sn ready
Up to 13 T
Can be idealIf affordable…ITER CS: 170M€
Capture SolenoidSummary & Issues
• For Pion Capture Solenoid for J-PARC– Detector Solenoid Technologies can be good solution
• Field ~5T, Heat Load ~10W (Beam Power ~56kW)
– More advanced technologies are also available• with some more money…
• Issues– High Radiation Doze
• Insulation material: Organic < 107 Gy
– High Neutron Fluence• Al and Cu: Resistivity change• Superconductor: Jc change
What about others
• Pion Capture– High Field– High Radiation
• Transport & Decay – Medium Field– Curved solenoid
• Experiment– Low Field– Large volume– Curved solenoid
Transport solenoid• COMET is not the only project
needing muon transport solenoid• Even in J-PARC there is a similar
curved solenoid needed– J-PARC MLF muon beam line– Lot of similarity in spec– Joint R&D
• Osaka Univ• KEK muon group• KEK cryogenics center
J-PARC Muon Beam Line
• Field; ~2T• Aparture; ~0.4 m
• Limited Access to shielded area– Refrigerator must be
outside of shield– Limited Space for the
refrigerators– Long distance to cold
head to coil front– Conduction Cooling with
Higher Temperature
Trial Winding of Curved Section with MgB2 conductor
• Purchase two kinds of MgB2 conductor from Columbus SC– 1 is the 1.13 mm diameter round wire
• Will be wound by a company
– 2 is the 1.5 * 2.5 mm square wire• Will be wound by Nakahara and Adachi at KEK
• They will be wound this winter and Tested in next spring
R&D Coil made at KEK in houseNbTiAlready woundTest just started
R&D on Transport SCSolenoid Coil by company
will be wound till Mar.
R&D on trim dipole coil
Trial Winding of Curved Section with MgB2 conductor
• Purchase two kinds of MgB2 conductor from Columbus SC– 1 is the 1.13 mm diameter round wire
• Will be wound by a company
– 2 is the 1.5 * 2.5 mm square wire• Will be wound by Nakahara and Adachi at KEK
• They will be wound this winter and Tested in next spring
MgB2 conductor actually purchasing
Monel 400 sheathed
Diameter: 1.13mmComposition MgB2 (Vol %) 14.6Fe (Vol %) 10.8Cu (Vol %) 13.8Ni (Vol %) 15.8Monel 400 (Vol %) 45.0
Monel 400 sheathed
Diameter: 1.13mmComposition MgB2 (Vol %) 14.6Fe (Vol %) 10.8Cu (Vol %) 13.8Ni (Vol %) 15.8Monel 400 (Vol %) 45.0
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8
0
50
100
150
200
250
300
350
400
Crit
ical
cur
rent
(A
)
Magnetic field (T)
16 K 20 K 24 K 30 K
Cost: 3€/m There is also 1.5 mm * 2.5 mm conductor
Themal Conductivity and Specific Heat of Cu and Al
89
100
2
3
4
5
6
789
1000
2
3
4
5
6
7
Thermal Conductivity (J/m2/K)
12 3 4 5 6 7 8 9
102 3 4 5 6 7 8 9
100T (K)
103
104
105
106
Specific Heat Capacity (J/K/m3)
Cu (RRR:50) Cu (RRR:100) Cu (RRR:200) Al (RRR:200) Al (RRR:500) Al (RRR:1000) Cu Al
NbTi MgB2
Thermal Conductivity: ~ 3 times betterCp: about 10 times larger
Refrigerator Performance
• Refrigerator Efficiency– Improve significantly at higher
temperature
7.2 kW
Transport SolenoidSummary
• MgB2 can be a good candidate– Operation Temperature 10~20 K– Better Refrigerator Performance– Best Thermal Conductivity– Better Specific Heat– Good Cost saving solution