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united nationseducational, scientific
and culturalorganization
international atomicenergy agency
thesinternational centre for theoretical physics
SMR 1331/19
AUTUMN COLLEGE ON PLASMA PHYSICS8 October - 2 November 2001
The Structure of the US FusionEnergy Science Program -
What Scientific Questions areWe Trying to Address?
R.J. Goldston
Princeton University, Plasma Physics Lab.Princeton, U.S.A.
These are preliminary lecture notes, intended only for distribution to participants.
strada costiera, I I - 34014 trieste italy - tel.+39 04022401 I I fax +39 040224163 - [email protected] - www.ictp.trieste.it
The Structure of the US FusionEnergy Science Program -
What Scientific Questions are WeTrying to Address?
Rob Goldston, DirectorPrinceton Plasma Physics Laboratory
October 15, 2001
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Fusion Plasma Science is In Pasteur's QuadrantProf. Donald Stokes, Dean, Princeton Woodrow Wilson School
Considerations of Use?No - Yes
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Edison
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Tight coupling of understanding and innovation.
Strong commitment to both!imVSRS tB»K§!8»
PPPL Mission Statement
The DOE Princeton University Plasma Physics Laboratoryis a Collaborative National Center for plasma and fusionscience. Its primary mission is to develop the scientificunderstanding and the key innovations which will lead toan attractive new energy source.
Associated missions include conducting world-classresearch along the broad frontier of plasma science andtechnology, and providing the highest quality of scientificeducation.
PPPL
CO2 Accumulation is a 100 to 200 Year Process
2000 2050 2100 2130 2200 2250 23002000
If CO2 is a problem, non-carbon emitting sourcesmust provide about half of the world's power by 2100.
PPPIHIBITH PUtSfflipgf SSJS
Plasma Science ChallengesNRC Plasma Science Committee
• Macroscopic Stability- What limits the pressure in plasmas?
• Geomagnetic substorms, Chandra data• Wave-particle Interactions
- How do hot particles and plasma wavesinteract in the nonlinear regime?* Coronal heating, laser amplification
» Microturbulence & Transport- What causes plasma transport?
* Astrophysical accretion disks• Plasma-material interactions
- How can high-temperature plasmaand material surfaces co-exist?* Materials processing
Fusion Plasma Science is Addressedthrough a "Portfolio Approach"
Scientific synergy - Common physics- Ideas from one configuration help others.- Hybrid configurations emerge.- Provides rigorous test of plasma science understanding.
Breadth - Complementarity- Range of configurations avoids common roadblocks.- Broadens science and technology impact of fusion science.
Leverage - > $1B/year International Program- Opportunities to access advanced scientific facilities abroad.
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The Portfolio of MFE ConfigurationsEiternally Controlled Self-Organized
'r'
Example: SteliaratorCoils link plasmaMagnetic fields from external currentsToroidal field » poloidal fieldLarge R/aMore stable, better confinement
Example: FRCCoils do not link plasmaB from internal currentsPoloidal B » Toroidal BR/a -> 1.0Higher power density
The Magnetic Fusion Energy Portfolio
tc 6
FusionEnergyDevelopment
PerformanceExtension
ProofofPrinciple
Attractive Fusion Energy Source
*^ I !1? ,.
Future/ Opportunity
Design Phase.
ConceptExploration
AdvancedSteliarator
AdvancedTokamak
Only U.S.Shown
Spherical j RFP.FRCTorus '< Spheromak
Emerging
Fusion Technology & Plasma Theory
Facilities both operating and under construction.
Innovative Confinement ConceptsExpand the Range of Stability Studies
Compact Auburn Torsatron tobecome Compact Toroidal HybridAuburn University, Auburn Alabama
Levitated Dipole ExperimentColumbia University/Massachusetts
Institute of Technology
Sustained Spheromak Plasma ExperimentLawrence Livermore National Laboratory
High-fit With Good Confinement
1.2
1.5
20
0.1
Plasma Current (MA)
1.3MW,Neutral Beam Power (MW)N
pt(%) (EFIT)
-0.1 *
f B. (Volts)
m- 4HA.
q 0 (EFIT)
-A.
0.1 0.2
Time (sec)
0.3
U I q^7J
At time of _maximum p.
NSTX is Beginning to Study Transport atHigh p and High Mach Number
• Broad Ts profile . '(compared to Te) o ,
• Large Tj - Te
• High V^ in core &edge
20 40 60 80 100 120 140 160RADIUS (cm) 2 0 4 0 6 0 8 0 1 0 ° 1 2 0 H 0 1 6 0
RADIUS (cm)
0.290s 14,200 -
High edge rotation
#104001
6!
4!....
20 40 60 80 100 120 140 160 Q 0.2 0.4 0.6 0.8 1RADIUS (cm) r/a
ft Bell, B. LeBlanc PPP1Hmmnim mmsm
Motional Stark Effect Measurements ofField Angle Revolutionized Stability Studies
• Motional Stark Effectdepends on v x B => E.- Linear effect in Do beam
injected into plasma.
• Allows measurement ofB field tilt => q profile.- Can get Er and |B| as well
as tilt => rotation & pressureprofiles,
• Developed! on PBX-M atPPPL by FP&T; revolutionizedstability studies.- Laser induced fiourescence
being developed for strongersignal in NSTX and otherlow field / high p* devices.
New Approach to Diagnosis andUnderstanding of Turbulence
GTC simulation:
Z. Lin
Parallelized simulationof |i-wave reflection:
E. Valeo, R. Nazikian
Data Interpretation(JT-60U)
j= 0.8Reflectometer
5 10 15 20Radial Displacement [cm]
System size ~ 200 X x 100 X
TextorGermany
R. Nazikian et al., IAEA 1998
ExperimentalDesign
PPPL
Simulation of microwave Imaging Experiment
Strong Theory / Experiment Collaboration PPPLtalHHtii PiBSiliIRBSMSliBiiSHSW
Opportunity: Physics link withAstrophysics via High Beta Turbulence
• Turbulence in accretion disks,active galactic nuclei may beamenable to codesdeveloped for fusion.
• Benchmark turbulence codes athigh beta in NSTX.
• Requires qualitative advance inplasma measurement:- diagnostics: spatial, low k, high k
resolution
• Key collaborators: U Maryland, UCBerkeley, UC Davis, PPPL
PofcMal Cross Section
From Chandra;our galaxy'score, 0.5-10keV x rays
ImagingReflectometry(PPPL, UC Davis)
t.O 1.2 1.4 1.6 1.8 2.0 Z2 2.4 2.6
A Proposed Experiment to Study MagnetorotationafInstability Important to Accretion Disk Physics
H. Ji (PPPL), J. Goodman (PU), A. Kageyama (NIFS), E. Shoshan (Rutgers)
Mechanisms of fast accretion /angular momentum transport inaccretion disks has been a longstanding problem inastrophysics
Magnetorotational instability(MRI) is an important candidatemechanism in MHD, but neverrealized in laboratory
Rotating gallium disk experimentcould create MRI and study itsrelations with other importantMHD physics, such as dynamo.Experiment with water is startingto test hardware and fluidstability
t t t t t t t t t t tB<1T Container
:=600 rpm
ST Development may be an Attractive Element of theWorld Program
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1.0
0.1
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Performancepxtension:R0~::1.5m
#roof of PrincipleNSTX, MAST (UK)
EnergyDevelopmentR0~1.5m
Concept ExplorationSTART (UK), CDX-U, Pegasus, Giobus-M (RF)
-ih _L1 0-8
(equiv)0.001 0.01 0.1
Neutron Fluence (MW-a/m2) per Year
Advance in Fusion Energy Technoiogy
Energy
1.0
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Strong Connection Between Stellarators and Other3D Plasma Physics Problems
Many other plasma problems are three-dimensional- Magnetosphere; astrophysical plasmas- free-electron lasers; accelerators- perturbed axisymmetric laboratory configurations
Development of 3D plasma physics is synergistic, with stellarator researchoften driving new 3D methods. Examples:- methods to reduce orbit chaos in accelerators based on stellarator methods
[Chow & Carry, Phys. Rev. Lett. 72,1196 (1994)]- chaotic orbits in the magnetotail analyzed using methods developed for
transitioning orbits in stellarators [Chen, J. Geophys. Res. 97,15011 (1992)]- astrophysical electron orbits using drift Hamiltonian techniques and magnetic
coordinates developed for stellarators- tokamak and RFP resistive wall modes are 3D equilibrium issues- transport due to symmetry breaking was developed with stellarators
We expect this connection to continue
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10
Gyro-averaging Allows a New Form of Symmetry
Hamiltonian formulation of Alfven gyro-averaged drift equations:
vgc = p|, (fl + V x pj,B)/(I + pp • V xb)Expressions for magnetic fields in canonical coordinates:
p
• Theorems by Boozer et al. show you can construct magnetic fieldconfigurations which have H symmetric (|B| symmetric) in canonicalcoordinates, but non-symmetric in configuration space.
• For compact stellarators - of special interest is toroidal symmetry.- Symmetry and compactness of the tokamak.- Stability and steady-state operation of the stellarator.
IPWSHS msmaiwm
New Stellarators Test Quass-Syrrsmetrlesand Disruption Immunity
Natural plasmas are asymmetric
Asymmetrical neoclassical transportscales as eeff
3/2
Low (adjustable) flow-damping
- manipulation of flows for flow-shear stabilization
- zonal flows like in tokamaks,but can be turned on and off
Test quasi-axisymmetry and MHDphysics at low v, and high p.
)edge
11
Compact Stellarators will Address KeyIssues of Fusion Plasma Science
1 Macroscopic Stability:
• Disruptions - when, why, why not?=> High p, 3-D stability to kink, ballooning,neoclassical tearing, vertical displacement.
Microturbulence and Transport:
• is quasi-symmetry effective at high Ts?Challenge Er shear understanding viarippie control.=> High T|, flexible coil system
Wave-particle Interactions:
• Do we understand 3-D fast ionresonances, *AE modes in 3-D?=> Good fast ion confinement
' Plasma-boundary interaction:
• Effects of magnetic stochasticity?==> High power, flexible coil system
Auburn U., Columbia U., LLNL, NYU, ORNL, PPPL, SNL-A, U. Texas, UCSD, U. Wisconsin
Australia, Austria, Japan, Germany, Russia, Switzerland!
National Compact Stellarator Experiment:Modular Coils have Flexibility for Physics Studies
(3=0, full current
Can externally controlrotational transform andshear.
Can adjust to avoid iota=0.5,or hit it in mid-radius.
Can accommodate widerange of p, j profiles.
Will allow systematicstudies of rotationaltransform and shear effectson ideal, resistive andkinetic (fast-ion)instabilities.
12
The World Adwanced Tokamak Program almsat an Attractive Steady-State Operating Mode
• An attractive steady-state tokamak power sourcerequires:- Relatively high beta (~ 5%)
• Feedback and/or rotational stabilization of resistive wallkink modes
• Feedback stabilization of neociassica! tearing modes- Strong self-sustained bootstrap current (~ 80%)
• Pressure profile control• Current drive and current profile control
• A strong international effort is underway todemonstrate the Advanced Tokamak mode:- US: C-MOD, DIII-D- EU: JET, ASDEX-U- JA: JT-6GU / JT-60SC- Korea: KSTAR v \ | P P P l
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13
Rotation Stabilizes Plasma "Kinks'to Higher Pressure
• Strong plasma rotation waspredicted to stabilize "kinks"to higher pressure.
• Columbia - Princeton - GAcollaboration to test feedbackcontrol of kinks on Dlll-D.
• Control of field errors allowedrotation to continue,
- stabilized kink to higherplasma pressure=̂> more fusion!
• Will be transferred to NSTX.
A Burning Plasma will Extendthe Reach of Fusion Plasma Science
• Macroscopic Stability- Effects of lower coSlisionality, smaller
gyro-radius.• Wave-particle Interactions
- Effects of intense, isotropic alpha particleconcentrations.
• Microturbu fence & Transport- Effects of lower collisionaSity, smaller
gyro-radius.• Plasma-material Interactions
- Much more intense, longer-lastinginteractions for study.
• Integrated demonstration of substantialfusion power production.- Relevant to a range of toroidal systems,
esp.: Advanced tokamak, ST, StellaratorIPtiKM mums;
14
Iter Addresses Burning Plasma andFusion Technology Issues
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pfusionQ
PulseMajor RadiusMinor RadiusPlasma CurrentToroidal FieldHeating/Current
Drive PowerCost ($2000)
500MW10500 - 2500s6.2m2.0m15MA5.3T
73MWS4.6B
FIRE EmphasizesBurning Plasma Physics Issues
"fusion
Q
Burn DurationMajor RadiusMinor RadiusPlasma CurrentToroidal FieldHeating PowerCost ($2000)
200MW10~20s2.14m0.58m7.7 MA10T30MW$1.25B
A more modest potential domestic step.PPPI
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15
Understanding, Innovation andCollaboration
Continuing deepening and broadening of thescience of plasmas is central to the innovationsneeded for the success of fusion energy research.
Plasma science itself is a beautiful and deepcontribution to world scientific culture.
Strengthening collaboration between areas ofplasma science and between plasma science andother areas is beneficial to all concerned.
jPPPLiHIVSia UMiHTOW
Not Science vs. Energy -Strong Commitment to Both!
• PPPL and the world fusion research communityare committed to providing the world with anattractive new energy source.
• We are also committed to deepening andbroadening the science of plasmas.
• The prospect is not a choice of "Science vs.Energy" but wonderful advances in both.
,PPPL
16