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Atlas for magneto-inertial fusion
Richard E. Siemon
6th Symposium
CURRENT TRENDS IN INTERNATIONAL
FUSION RESEARCH: A REVIEW
7-11 March 2005,
Washington, DC, U.S.A.
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SynopsisMagnetized Target Fusion (MTF) is the approach to fusion energy that is intermediate inparameters between conventional magnetic and conventional inertial fusion. Typical
parameters are microsecond time scales, megabar pressures, megagauss magnetic field, andmegajoules of energy. The essential ingredients are formation of a plasma target containing thefusion fuel embedded in a magnetic field to improve energy confinement, followed by pulsedcompression of the fuel to achieve fusion reactions during the inertial dwell time of thecompression system. A variety of detailed approaches are being considered for this purpose.1-4
Theoretical analysis shows that the intermediate regime of parameters has better prospects for
economical development of practical fusion energy than either extreme represented byconventional approaches.5
This year the Atlas pulsed power facility, designed and developed at Los Alamos NationalLaboratory, is beginning to operate at the Nevada Test Site. It is the worlds largestmicrosecond pulsed power system. Given that the primary purpose of Atlas is high-energy-density science for stockpile stewardship, it is serendipitous that Atlas is also extremely well
suited for critical tests of the magneto-inertial fusion concept.The design of an initial experiment on Atlas will be described that investigates magnetic fluxcompression without plasma, and generation of magnetic field in the megagauss regime.6 Annew and interesting aspect of the experiment is a unique method of providing seed flux forcompression by diverting a small amount of current from the main Atlas power system while itdrives a liner implosion.
Progress on formation of an MTF plasma target has been recently reported by Los Alamosresearchers,7 and other possibilities are being investigated.8 Plans for a campaign of Atlasexperiments based on this progress are being developed. This campaign is one part of aroadmap for developing the MTF concept, which was recently prepared by the internationalcommunity of scientists interested in MTF. The roadmap shows how Atlas in combinationwith other existing pulsed power facilities can provide a faster pathway to fusion than possiblewith conventional approaches.
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References
1. D.D. Ryutov and R.E. Siemon, Comments on Modern Physics 2, 185 (2001).2. Y.C.F. Thio, C.E. Knapp, R.C. Kirkpatrick, R.E. Siemon, and P.J. Turchi, J. Fusion Energy
20, 1 (2001).
3. F. Winterberg, Phys. Plasmas 11, 706 (2004).
4. A.J. Kemp, M.M. Basko, and J. Meyer-ter-Vehn, Nucl. Fusion 43, 16 (2003).
5. R.E. Siemon, P.J. Turchi, D.C. Barnes, J.H. Degnan, P. Parks, D.D. Ryutov, F.Y. Thio, Proc.12th International Toki Conference, Toki, Japan (2001).
6. T.S. Goodrich, R.E. Siemon, B.S. Bauer, T.E. Cowan, I.R. Lindemuth, V. Makhin, R. Faehl,R. E. Reinovsky, 46th Annual Meeting of the Division of Plasma Physics, Savannah, Georgia,Nov. 15-19, 2004
7. G. A. Wurden, T. P. Intrator, S. Y. Zhang, I. G. Furno, S. C. Hsu, J. Y. Park, R. Kirkpatrick,
R. M. Renneke, K. F. Schoenberg, M. J. Taccetti, M. G. Tuszewski, W. J. Waganaar, ZhehuiWang, R. E. Siemon, J. H. Degnan, D. G. Gale, C. Grabowski, E. L. Ruden, W. Sommars, M.H. Frese, S. Coffey, G. Craddock, S. D. Frese, N. F. Roderick, Paper IC/P6-53, Proc. 20thIAEA Fusion Energy Conference, Vilamoura, Portugal (2004)
8. R.E. Siemon, W.L. Atchison, B.S. Bauer, A.M. Buyko, V.K. Chernyshev, T.E. Cowan, J.H.Degnan, R.J. Faehl, S. Fuelling, S.F. Garanin, A.V. Ivanovsky, I.R. Lindemuth, V. Makhin,
V.N. Mokhov, R.E. Reinovsky, D.D. Ryutov, D.W. Scudder, T. Taylor, V.B. Yakubov, PaperIC/P6-48, Proc. 20th IAEA Fusion Energy Conference, Vilamoura, Portugal (2004).
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Terminology
Magneto-inertial fusion (MIF) is the general idea of achieving fusion with ahigh-density pulsed system that incorporates magnetic field
--magnetic field to improve energy confinement during burn
--high-energy-density achieved with high-power pulsed technology
--time scale governed by inertia of material surrounding the heated fuel
Magnetized Target Fusion (MTF) is the subset of MIF approaches that seeks
to work at a density intermediate between conventional inertial and magnetic
systems.
--preheat the fuel and compress to thermonuclear temperature with one of
several possible pushers.
--metal liners and pulsed systems like Atlas are available now to test basic
concept
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FRC plasma target
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DT Fuel Mass heated to10 keV
103
Required DT Fuel Mass
Density (gram/cm3
)
1
10-3
10-6
10-9 10-6 10-3 1
FuelMass(grams)
Diffusion-limitZero magneticfield
NIF
ApproximateUpper-limit Bohm
Advancedconcepts
ITER
Diffusion-limitclassical magnetic confinement
MTF
FuelE
nergy(joule
s)
106
109
103
MTF regime is intermediate between MFE and ICF
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Intrinsic fusion cost considering size andpower is minimized around 1 Mbar
10
100
1000
10000
1.E+02 1.E+04 1.E+06 1.E+08 1.E+10 1.E+12
ITER-FEAT
FIRE
NIF
Z
Atlas
Generic MTF
Nominal tokamak
High pressure tokamak
Fuel pressure (megabar)
0.0001 .01 1 100 10000
Facilitycost($M
)
10
100
1000
10000
1.E+02 1.E+04 1.E+06 1.E+08 1.E+10 1.E+12
ITER-FEAT
FIRE
NIF
Z
Atlas
Generic MTF
Nominal tokamak
High pressure tokamak
Fuel pressure (megabar)
0.0001 .01 1 100 10000
Facilitycost($M
)
See Siemon et al.,
Toki conference (2001).
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MIF can be developed faster thanconventional fusion
Road map analysis suggests a time scale of 20
years instead of 50 yearsCost of development is reduced because
facilities are intrinsically less expensive.
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Concept ExplorationPlasma target experiments & Liner tests
Theory & Modeling
~ $5 M/year
Proof-of-Principle
Atlas facility / Variety of targets~$20M/y
Performance Extension
Atlas & Engineering Prototypes
$30-50M/y
Energy Development
Demo$1B
Commercialization
Power plant$2B
2015
NASA Development
Ground-based rocket$1B
Manned Exploration
of Solar System
Stockpile Stewardship
Intense neutron source$300M
20122012
Integrated plasma-on-liner test
T~1 KeV, Qeff~0.01
Economic feasibility
demonstrated
Engineering & Economics
demonstrated
PoP experiment
Qeff~1
Mission adopted
Rocket-specific
technology
demonstrated
Technology,
Materials,Theory,Ad
vancedComputing
R
ampingto~$10M/yatProof-of-Principle~$2
5M/yatPerformanceE
xtension
Magneto-inertial Fusion Roadmap
Design based on
mission requirements
Spac e Energy Defense
20252025
2010
2007
Concept ExplorationPlasma target experiments & Liner tests
Theory & Modeling
~ $5 M/year
Proof-of-Principle
Atlas facility / Variety of targets~$20M/y
Performance Extension
Atlas & Engineering Prototypes
$30-50M/y
Energy Development
Demo$1B
Commercialization
Power plant$2B
20152015
NASA Development
Ground-based rocket$1B
Manned Exploration
of Solar System
Stockpile Stewardship
Intense neutron source$300M
20122012
Integrated plasma-on-liner test
T~1 KeV, Qeff~0.01
Economic feasibility
demonstrated
Engineering & Economics
demonstrated
PoP experiment
Qeff~1
Mission adopted
Rocket-specific
technology
demonstrated
Technology,
Materials,Theory,Ad
vancedComputing
R
ampingto~$10M/yatProof-of-Principle~$2
5M/yatPerformanceE
xtension
Magneto-inertial Fusion Roadmap
Design based on
mission requirements
Spac e Energy Defense
2025202520252025
20102010
20072007
Roadmap
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Atlas power supply
Standard person
240 kV
24 MJ~ 25 nH30 MA
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Atlas is ideal for doing importantMTF experiments
Near term -- magnetic flux compression to
megaguass field level in an MTF-relevant
geometry
Longer term using various plasma targets,
test plasma compression inside a liner
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Flux compression experiment isbeing designed
z
Atlas Bank Current
Conductinghard core
5cm
5mm
Insulator
Metal
Liner
Shunt
z
Atlas Bank Current
Conductinghard core
5cm
5mm
Insulator
MetalMetal
Liner
Shunt
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Liner implosion with trapped fluxresults in megagauss magnetic field
Magnetic Field and Radius vs Time
0102030
4050607080
90100
0 5 10 15
Time(s)
Radius(mm)
B-500(T)
B-200(T)
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Hard-core stabilized z pinch ispotential MTF target plasma
B
Plasma
current
Hard core
current
B
Plasma
current
Hard core
currentPlasma
Outer conductoris the imploding liner
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MAGO generates hard-corestabilized z pinch
MAGO at VNIIEF
I. R. Lindemuth, et al., Magnetic
Compression / Magnetized Target Fusion
(MAGO/MTF): A Marriage of Inertial
and Magnetic Confinement, 16th IAEAFusion Energy Conference, Montreal,
Canada, October 7-11, 1996.
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Self-organization indiffuse z pinch
Plasma is unstable if pressure gradient violates Kadomtsevcriterion
Result is turbulent interchange motions of flux tubes in the rzplane (B=B).
Plasma fluctuates in space and time around the marginalKadomtsev-stable pressure profile.
Process observed in numerical simulations of many different
initial conditions; consistent with MAGO experimental data. Process illustrated by simulation using idealized initial
conditions with eg. pressure gradient 10% too large
See Makhin et al., Physics of Plasmas, April 2005
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Sequence of interchange motionfollowing Q=1.1 initial profile
Z(m
)
Plasma density contours (color) and velocity streamlines
R(m)t = 1.0 s t = 2.0 s
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Last moment of interchange before chaotic mixing;Mass contours and velocity stream lines
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Chaotic mixture after interchange;
mass contours and velocity stream lines
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Diffuse z pinch target on Atlas
z
Atlas Bank Current
Hard core
5cm
5mm
Coaxial Plasma Injector
Insulator
Metal
Liner
Switch
z
Atlas Bank Current
Hard core
5cm
5mm
Coaxial Plasma Injector
Insulator
MetalMetal
LinerLiner
SwitchSwitch
Plasma injector and Atlas Bank
are separate electrical circuits
Coaxial injector could be aMAGO device or a Marshall
Gun type accelerator
Liner region labeled switchcauses the plasma injection gap
to close at the beginning of liner
compression
After switching action plasmawith flux is trapped in a
toroidal chamber surrounding
the hard core, and
compressional heating occurs as
the liner implodes.
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Liner driven by Atlas(Raven 1D code)
-10
0
10
20
30
40
50
60
0 5 10 15 20 25 30
Liner outsideLiner inside
Current
Hard core
R
adius(mm);Current(MA)
Time (s)
-10
0
10
20
30
40
50
60
0 5 10 15 20 25 30
Liner outsideLiner inside
Current
Hard core
R
adius(mm);Current(MA)
Time (s)
0
0.1
0.2
0.3
3.5 4 4.5 5
Radius (mm)
Tempera
ture(eV)
Boil
Melt
20 s
21 s
19 s
0
0.1
0.2
0.3
3.5 4 4.5 5
Radius (mm)
Tempera
ture(eV)
Boil
Melt
20 s
21 s
19 s
Initial liner 50-mm radius,
10-cm long, 2-mm thick
Surface of hard core reaches
boiling temperature just beforetime of maximum compression
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2D MHRDR simulation results
18 20 22 24 260
20
R(mm)
18 20 22 24 26-5
0
5
V
km/s
18 20 22 24 260
5
10
/1024(m-3)
18 20 22 24 260
5
(s)
(keV)
VelocityLiner inner radius
Hard-core radius
t(s)
18 20 22 24 260
20
R(mm)
18 20 22 24 26-5
0
5
V
km/s
18 20 22 24 260
5
10
/1024(m-3)
18 20 22 24 260
5
(s)
(keV)
VelocityLiner inner radius
Hard-core radius
t(s)
--compressible two-fluid model
--Braginskii coefficients of thermalconduction and electrical resistivity.
--Ohms law is E+vxB= j-- No Hall terms or thermoelectric termssuch as Nernst current included.
Neutrons ~ 4x1012
Excellent diagnostic
See Siemon et al., NuclearFusion, to be published (2005).
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Compressed plasma turbulentstructure
time= 2.290e-005s
5.2 5.4 5.6 5.8 6 6.2
x 10-3
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
500
1000
1500
2000
2500
3000
3500
4000
5.5 6 6.5
x 10-3
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
0.05
time= 2.290e-005s
9.2
9.4
9.6
9.8
10
10.2
Temperature contours& white streamlines
Pressure contours
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Issues that need study
Modeling of plasma formation process by MAGO or othercoaxial generators is needed.
Transport modeling should include estimates for Bohmmicroturbulence, wall-plasma interaction, sheath physics, andradiation from impurities.
A coating of lithium on walls (optionally including dissolvedhydrogen fuel) offers the possibility of low-Z contamination.
Future simulations should examine radiation from a lithium-hydrogen plasma mixture.
Hall terms and thermoelectric terms such as Nernst current
(not in simulation) need further investigation.
RS, VM, BSB 5/26/03
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MTF Team
HyperV Technologies
U. Wisconsin
U. Colorado
U. Washington
UNR
UNLV
NTSLLNL
UCDavis
GA
LANL
AFRLNASA
MSFC
Groups funded (often small) or proposing to work on MTF
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Summary
An exciting possibility to advance fusion with MTF on Atlaspresents itself.
Results from MTF exploratory experiments on Atlas andShiva Star in the next two years will motivate a larger MTFProof-of-Principle campaign on Atlas.
International team is in place to do this work.
Proposed plan has small impact upon other DP plans and
resources; valuable method for recruiting DP manpower.
The moment is right for a significant MTF initiative
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