magnet design considerations & efficiency advantages of magnetic diversion concept
DESCRIPTION
UCRL-PRES-210109. Magnet Design Considerations & Efficiency Advantages of Magnetic Diversion Concept. W. Meier & N. Martovetsky LLNL HAPL Program Meeting NRL March 3-4, 2005. Work performed under the auspices of the U.S. Department of Energy by the University of California, - PowerPoint PPT PresentationTRANSCRIPT
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Magnet Design Considerations& Efficiency Advantages
of Magnetic Diversion Concept
W. Meier & N. MartovetskyLLNL
HAPL Program MeetingNRL
March 3-4, 2005
Work performed under the auspices of the U.S. Department of Energy by the University of California,Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48.
UCRL-PRES-210109
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Meier HAPL March 05 2
Many system trades need to be considered for magnetic diversion concept
• Costs
+ Chamber (smaller chamber lower cost first wall and blanket)
– Magnets, cryo refrigeration system, magnet structural support and shielding
– Ion dump (ion dump “first wall”, cooling, shielding)
• Performance
+ Lower first wall heat flux more options for FW coolant
+ Possible higher operating temp higher thermal conversion efficiency, but
- requires advanced materials higher costs, longer development time?
+ Possible direct conversion of ion energy possible higher conversion eff., but
- requires added equipment, cost and complexity
• Nuclear Considerations
– Small chamber shorter FW life for given fusion power
– Neutron leakage thru ion port reduced TBR, shielding issues
– Need to shield cryo magnets
+ Ion dump wall out of direct line of sight of neutrons less n damage
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Meier HAPL March 05 3
ITER Central Solenoid (CS) Cable in Conduit Conductor (CICC)
Conductor consists of:• Nb3Sn superconducting strands• Pure copper strands• Multi-stage cable including wraps and central spiral• Jacket
– Extruded segments 4-8m long– Butt welded/inspected– Cable inserted and compacted
CICC(49 mm x 49mm)
Strand Nb3Sn
(0.83 mm diameter)
Conductor in winding pack:
1 mm per side insulation
1 mm axial shim
0.5 mm radial shim
Shims are used to compensate winding errors and keep winding pack tolerances
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Meier HAPL March 05 4
CS CICC Construction
Conduit
Cable wrap (protects cable against damage during pull through)
Subcable wrap (to reduce AC losses)
Strand
Subcables Helium flow
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Meier HAPL March 05 5
ITER PF Conductor (NbTi+Cu)
Strand (courtesy of EMI, 0.81 mm diameter, Ni plated)
CICC in 316 LN steel jacket, 1152 strands
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Meier HAPL March 05 6
PF magnets for ITER are similar in size and complexity – possible prototype
12.5 m
PF2 is about same radius as our middle magnets
PF3 is about same radius as our deflector magnet
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Meier HAPL March 05 7
Conceptual design of the magnet system
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Meier HAPL March 05 8
Peak field is 5.4 T at inner edge of smaller radius (3.25 m) coils – allows NbTi CICC
Field, T
Field, T
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Meier HAPL March 05 9
Forces and stored energy are significant, comparable to ITER PF coils
1 30.0 -14.02 29.3 14.83 24.2 83.04 7.2 31.65 20.4 -115.0
Mag Hoop Axial
Forces, 106 N
1
2
3
5
4
Stored energy in system = 2.9 GJ – very significant,
requires good quench detection and protection
system (dump resistors, fast circuit breakers).
Arrows indicate direction of forces. (Not to scale)
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Meier HAPL March 05 10
ARIES is developing magnet costs and scaling for Compact Stellerator study
From L. Bromberg and J. Shultz, “ARIES CS Magnets” PPPL Meeting, 12/4/04
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Meier HAPL March 05 11
Near-term, real world cost info is available from ITER
1 IUA = $1000 (1989$) ~ $1360 (2005$)** escalated using US producer prize index for manufacturing
~ $100M(2005$) forsix PF coils
PF5: I = 9.8 MA-turns, R = 8.4 m Cost ~ $19.6M (14.4M IUA)
IFE5: I = 9 MA-turns, R = 7.85 mIf Cost ~ Vol, then Cost ~ $17M
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Meier HAPL March 05 12
Power flow diagram with direct conversion
Chamber:Target
gain (G)
Laser (d)
Blanket(x M)
Neutrons & x-rays(~70%) HGH
Steam orBrayton
cycle(t)
Charged particles& plasma (~30%)
HGH = High Grade Heat
DirectConverter
(i)
HGH
Laser poweron target
Pd = laser power
Pne = net electric power
Pte = thermal-electric
Pde = direct-electric
Adapted from A.E. Robson
Pe = gross electric
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Meier HAPL March 05 13
Efficiency improvement using DC is easily implemented in systems code
Overall conversion efficiency for gross power
g t i Pe t i Pnx Pi
Driver power
Pd ERR
d
Net electric power
Pne t d Pe t d Pd
Overall conversion efficiency for net power
n t i Pe t i Pd
Pnx Pi
Fusion Power
Pf E G RR
Neutron + x-ray power including blanket multiplication
Pnx 0.7 Pf M
Ion/plasma power
Pi 0.3 Pf
Electric power from direct conversion
Pde i Pi i
Electric power from thermal conversion
Pte t i Pnx 1 i Pi t
Gross electric power
Pe t i Pde i Pte t i
E = driver energyG = Target gainRR = Rep-rateM = Blanket multiplication
d = driver efficiency
t = thermal-electric conversion efficiency
i = ion-electric conversion efficiency
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Meier HAPL March 05 14
Net plant efficiency can be significantly higher with DC of ion energy
Net
eff
icie
ncy
Ion-to-electric efficiency
0 0.1 0.2 0.3 0.4 0.50.3
0.32
0.34
0.36
0.38
0.4 Assumes:• Gain = 140• Laser eff. = 7%• Thermal eff. = 40%• Ion dump heat also converted at 40%
50% DC = 38.9%No DC = 30.5%
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Meier HAPL March 05 15
COE could be significantly lower depending on added costs of magnets and direct conversion
0 0.1 0.2 0.3 0.4 0.50.75
0.8
0.85
0.9
0.95
1
Ion-to-electric efficiency
Nor
mal
ized
CO
E
No added capital cost
10% higher capital cost
Assumes:• Same as previous• COE ~ (Capital cost)/Pne
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Meier HAPL March 05 16
Next Steps?
• Next steps depends largely on level of detail desired for evaluation of magnetic diversion concept
• Need more info on
– Choice of FW and blanket for chamber
– Design of ion dumps and cooling method
– Direct conversion systems and costs
• Good start on basis for magnet design, costs and scaling
• Potential plant efficiency improvements are significant, but will be offset to some degree by added costs for magnets, ion dumps and conversion equipment.