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The High-Magnetic-Field Path To Practical Fusion Energy · 8/30/2017 High Field Path To Fusion 10...
Transcript of The High-Magnetic-Field Path To Practical Fusion Energy · 8/30/2017 High Field Path To Fusion 10...
The High-Magnetic-Field Path To Practical Fusion Energy
Presented by Martin Greenwald for MIT-PSFC TeamAugust 30, 2017
ARPA-E Annual Review – San Francisco
Acknowledgements
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Many contributions, particularly from
– ARC Team
– Dan Brunner
– Zach Hartwig
– Earl Marmar
– Joe Minervini & PSFC Magnet Group
– Bob Mumgaard
– Brandon Sorbom
– Dennis Whyte
Common Ground
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● Focus on mission, product, customer
● Need to move fast
● Centrality of Innovation
● Agile approach - Identify and retire risks at lowest cost
● Desire to raise the profile of fusion energy – place into the discussion of our energy future
Where we differ – technical approach
● MIT stresses robust and aggressive magnet engineering harnessed to proven physics
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The World Needs Reliable Carbon-Free Energy
Can Fusion Contribute To The Solution?
Dilemma - The Physics Is Mature, But… The Conventional Path Is Too Big, Too Slow
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2015 2020 2025 2030 2035 2040 2045 2050
$50 B $10 B ??$30 B ??
JETNow operating
JT-60SAUnder construction, 2019
ITER First plasma 2026
D-T 2035-2040
FNSF/Pilot (US)2040-2045 start?
DEMO (EU)2060 start?
First power on grid in >2070
Is There A Faster, Cheaper Way?
Before They Got Too Big, Tokamaks Demonstrated Enormous Progress
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Progress Exceeded Moore’s Law for 30 years
JT-60U (JP) KSTAR (KR)
NSTX-U (US) Tore Supra (FR)
HT-7 (CN)
MAST-U (UK)
COMPASS (CZ)
EAST (CN) JET (EU)DIII-D (US)
ASDEX-U (DE)Alcator C-Mod (US)
+ 170 other tokamaks across 60 yearsEnormous technical and scientific base
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● HTS technology has emerged into industrial maturity
● Form factor ideal for high-field fusion magnets
– Higher current densities
– Higher operating temperatures
– Strong (mostly steel) substrate
We Think The Basis For Breakthrough Is Here – High Temperature Superconductors
Why Do We Care? At Higher Fields, Fusion Reactors Can Be Smaller
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● Fusion requires achievement of certain absolute parameters (bracketed by nuclear and atomic physics) ⇒ size matters
– The “size” of the plasma is properly measured in ion gyro-radii ⇒ B×R is critical figure of merit
● Using “Standard” assumptions we can map out tokamak fusion performance
Why Do We Care? At Higher Fields, Fusion Reactors Can Be Smaller
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● Fusion requires achievement of certain absolute parameters (bracketed by nuclear and atomic physics) ⇒ size matters
– The “size” of the plasma is properly measured in ion gyro-radii ⇒ B×R is critical figure of merit
● Using “Standard” assumptions we can map out tokamak fusion performance
– Best LTS (Low Temperature Superconductor) is Nb3Sn; Large-volume fusion magnets can’t have much more than 5-6 T on axis
– Result: Machines are huge
Inaccessible with LTS Magnets
ITER
Why Do We Care? At Higher Fields, Fusion Reactors Can Be Smaller
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● Fusion requires achievement of certain absolute parameters (bracketed by nuclear and atomic physics) ⇒ size matters
– The “size” of the plasma is properly measured in ion gyro-radii ⇒ B×R is critical figure of merit
● Using “Standard” assumptions we can map out tokamak fusion performance
– Best LTS (Low Temperature Superconductor) is Nb3Sn; Large-volume fusion magnets can’t have much more than 5-6 T on axis
– Result: Machines are huge
● HTS ⇒ Double the field, cut the linear size in half. The volume, weight decrease by a factor of 8
ITER Fusion Pilot Plant Concept
ARC
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Why Do We Care? At Higher Fields, Fusion Reactors Can Be Smaller
ARC9.2 T500 MW Fusion PowerWith same physics
ITER5.3 T500 MW Fusion Power
Increase B
ARC: Concept for Modular Fusion Pilot Plant
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●Originated in a Graduate design seminar at MIT
– Challenge was to use HTS to find the smallest machine that would produce 500 MW fusion power - using physics from existing experiments
– Reference: Sorbom et al., Fusion Engineering and Design 100, 378, 2015
●Not an engineering design, but
– Sufficient mechanical, hydraulic, nuclear and electrical calculations were performed to suggest engineering plausibility for this class of device
What’s The Basis For Our Confidence In This Path?
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1970 1980 1990 2000 2010 2020
Record Plasma Pressure (MFE)
High confidence in Tokamak physics performance
Record nτELawson number exceeded 1983
10cm
26T YBCO
C-Mod 8T Demountable magnet
12T Alcator C9T Alcator A
ITER Model CS
Levitated SC Coil
Twisted Stack HTS
First 10T SC Fusion Magnet
Invented CIC Superconductor Cable
High-Field Copper Magnets
<p> > 2 ATMn = 4×1020/m3
T = 5 keVτE = 0.1 sec
Alcator C-Mod, as a compact, high-field device performs as well in many metrics as devices up to 100x larger and more costly at the national and international scale
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JT60Japan3 Tesla
Alcator C-ModMIT
8 Tesla
JETEurope3 Tesla
Demonstrates the cost-effectiveness of the high-field approach
Innovations – Fast and Furious
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● HTS – High Field, Compact Size
– Cheaper, faster
– Modular – fabricate in factory, assemble on site
● Demountable Magnet
– Vastly improved fabrication & maintenance
● Immersion molten-salt blanket
– When core wears out – replace it
– Dramatically reduced solid radwaste (x50)
● Long-leg, x-point target divertor
– Fully detached operation
● High-field side LH current drive for sustainment
Upper halfOf TF
Lower halfOf TF(ToroidalField) coils
Vacuum vessel containing complex internals
Liquid blanket tank
When the core wears out, just replace it like fission.
Common Ground – Revisited
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To move ahead – issues we all face
● Regulation/licensing
● Siting
● Fuel Availability and Fuel Cycle
● Public perception/acceptance
● Zero-carbon incentives and tax credits
● Need for independent validation
– Safety
– Technical
– Economic
Moving Forward
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Now is the time
● Convene interested parties – build the required coalition
● Take the processes into our own hands
● Address common interests
– Private/Public relationship
– Begin to drive the regulatory process
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END
The narrative that high-performance tokamaks have to be big, & expensive in slow unwieldy programs is not true.
• There are some small very high performance early tokamaks
Alcator CMIT 197812 Tesla
Alcator AMIT 196910 Tesla
• These were enabled by a cutting edge technology at the time• High-field, cryogenically-cooled, high-strength copper
magnets developed for magnetic science (MRI, NMR, etc)• They were early, inexpensive, small, team-oriented, and quickly
constructed on a university campus• These, what might qualify as “startups”, beat the large devices
at the national labs to get the Lawson criteria above breakeven
Alcator C-Mod performs as well in many metrics as devices up to 100x larger and more costly at the national and international scale.
Approximately to scale
JT60Japan3 Tesla
Alcator C-ModMIT
8 Tesla
JETEurope3 Tesla
• It is well demonstrated that within tokamaks, high-performance can be achieved at small size
• Despite its size, C-Mod is a very high performance device• Operated in fusion-relevant regimes of plasma physics
(e.g. thermonuclear Te=Ti )• Contributes important data to the understanding of
tokamak operation
World-record tokamak pressure
7 keV
High D-D fusion yields
Alcator C-Mod achieves record breaking plasma performanceat small size and high field.