Perspective on Fusion Energy Strategy
By

Tony S. Taylor
With
M. WadeW. Solomon

Presented at

NAS Committee for a
Strategic Plan for U.S.
Burning Plasma ResearchAugust 29, 2017
1

T. S. Taylor/NAS Committee/Aug 29, 2017

Fusion Energy is at a Crossroads in the U.S.
• ITER construction underway

ITER– Exciting and vital validationof the fusion energy concept

Central Solenoid• World program considering major facilities beyond ITER

EU DEMO

K-DEMOJapan DEMO

World program is moving ahead aggressively
with fusion energy development.
What path with the U.S. take?
2

T. S. Taylor/NAS Committee/Aug 29, 2017

CFETR

Your Charge to Me
We would especially appreciate learning your views on:1) The importance of U.S. burning plasma research to the development of fusionenergy,2) The scientific and technical developments since the 2004 report of the NAS Burning
Plasma Assessment Committee
3) The current status of U.S. research that supports burning plasma science including
U.S. scientific support for ITER
4) Any strategic elements that might strengthen or accelerate U.S. burning plasma
research given that economical fusion energy within the next several decades is a
U.S. strategic interest.

3

T. S. Taylor/NAS Committee/Aug 29, 2017

Importance of Burning Plasmas

Executive Summary:• Burning plasmas are a critical next step towards the realization of fusionenergy• Tokamak physics is sufficiently advanced to support burning plasma step,and the tokamak remains the only fusion concept mature enough toproceed to the burning plasma step
• Strongly recommend that this committee reaffirm the importance ofburning plasmas in fusion energy development, the highly developed
status of tokamak plasma science, and the unique opportunity that ITER
provides the U.S.

4

T. S. Taylor/NAS Committee/Aug 29, 2017

Burning Plasma: First Major Step on Path to Fusion Energy
Other Steps: Build on a Burning Plasma to Complete•

For DEMO, technical readiness must be
established for:- Fusion power source- Materials- Breeding Tritium & Extracting Heat•

Successful burning plasma
experiment facilitates progressin materials and blanket
technology

Fusion Energy
Deployment

Integrated
Demonstration

Materials
Tritium Breeding
Heat Extraction

Burning Plasmas

Scientific
Basis

5

Foundational Science & Technology

T. S. Taylor/NAS Committee/Aug 29, 2017

A Burning Plasma Will Enable Frontier Fusion Science• Self-sustained fusion plasma is a highly nonlinear system– Self-generated heating & magnetic fields à complex behavior– “Grand Challenge” for theory and numerical modeling• A burning plasma experiment and the supporting scientific program will
advance basic plasma science– Plasma turbulence, magnetic field line reconnection,
wave-particle interactions, …
– Applicable in other regimes (e.g. astrophysical plasmas)“A burning plasma experiment can offer substantive and important contributions
to other fields of science connected to plasma physics, primarily throughexperimental access to the fundamental and/or extreme conditions offered bysuch a state.”– Burning Plasma, NRC Report

6

T. S. Taylor/NAS Committee/Aug 29, 2017

Burning Plasmas are both a Challenge
and an Enormous Scientific Opportunity• Challenge: Produce burning plasma
conditions and then maintain them
– Achieve necessary density/ temperature/
confinement (n T τ)

JET

C-Mod

MAST

ASDEX-U

JT-60SA

Physics Basis– Operate safely at high plasma pressure– Handle concomitant heat/particle flux

DIII-D

NSTX– Minimize/Eliminate effect of transients• Opportunities enabled:

TCV

EAST

KSTAR

Realization– Alpha-particle impact on stability &turbulence

ITER– Turbulent transport and resistive MHD at low
ρ* (relative gyroradius) and rotation– Fusion burn stability, control, andpropagation– Strong, non-linear coupling of heating,current drive, turbulent transport, MHD
stability and boundary plasma

7

SST-1

T. S. Taylor/NAS Committee/Aug 29, 2017

Exploitation

A Burning Plasma Experiment Drives
Advances in Fusion Technologies•

Large, high field magnets– superconducting if long pulse• Remote maintenance and handling•

Tritium processing systems•

Hardened diagnostics•

High heat flux energy removal systems•

Long pulse, high power density heating
and current drive systems•

Plasma current quench detection/
remediation systems•

Integrated control systems for the nuclear
plant and plasma, including burn control•

Desired: test blankets for tritium breeding

•

…

8

T. S. Taylor/NAS Committee/Aug 29, 2017

Tokamaks Presently at Highest Level of Readinessof Any Concept to Exploit Burning Plasmas• Achieved tokamak performance is
two orders of magnitude above otherconcepts• Physics basis is well established(ITER Physics Basis in NF 1999, 2007)- Recent advances in later section• Strong Worldwide Research Program- Complementary and versatile facilities- Well diagnosed à solid science- Theory & simulation à prediction- Advanced plasma control- Large, capable work force

Tokamak is well positioned for continued
scientific advances and innovation

9T. S. Taylor/NAS Committee/Aug 29, 2017

ITER

Stellarator ~2020

Previous Panels Have Affirmed the Importance of Burning
Plasmas and Opportunity to Participate in ITER
NRC Burning Plasma Report 2004•

“Participation in a burning plasma experiment is a criticalmissing element in the U.S. fusion science program”.

•“The United States should participate in the International
Thermonuclear Experimental Reactor (ITER) project”•“Progress toward the fusion energy goal requires this
step”

•

“There is now high confidence in the readiness toproceed to the burning plasma step.”•“The tokamak is the only fusion configuration ready for
implementing such an experiment.”

NAS Decadal Study 2010•

“It is clear that the next critical step in the developmentof fusion power is a burning plasma experiment. ITER isthat step.”

Strongly recommend that this NAS committee reaffirm
the importance of burning plasmas and the unique
opportunity of ITER
10

T. S. Taylor/NAS Committee/Aug 29, 2017

Scientific Developments since 2004 NAS Report

Executive Summary:• The understanding of key physics governing underlying performance hasadvanced dramatically• The U.S. fusion program remains at the forefront of fusion science.
• Research since the NAS Burning Plasma Report (2004) has strengthened
our confidence in burning plasma (ITER) performance.

11

T. S. Taylor/NAS Committee/Aug 29, 2017

Scenarios Match ITER Q=10 Dimensionless Parameters
Relevant to Fusion Power & Gain in Present-Day Expts
ITER baseline

Advanced

Issue

ITER Physics Basis (1998, 2007)

Present

Rotation

Co-NBI, high rotation

Zero applied torque solutions foundElectron heating

Ion dominant

Electron dominant heating explored

Operational issues

Basic EC/low voltage startup,
rampdown in constant shape

Integrated tests of EC startup andrampdown with shape control

ELM mitigation

First indications of mitigation by
RMP

RMP ELM suppression in baseline andadvanced scenario, pellet pacing

Heat flux mitigation

Basic radiative divertor
demonstration

Radiative divertor in operating scenario

Disruption
mitigation

Basic physics understood

MGI and SPI tested

PMI

Mostly in graphite walls

Direct tests of ITER-like wall

12

T. S. Taylor/NAS Committee/Aug 29, 2017

Theory-Experiment Validation Has Increased Confidencein ITER Achieving its Q=10 mission
2004 status:• Manually-intensive “Herculean” simulations. Missing first principle pedestal model,
rotation etc
Plasma and Fusion Research: Regular Articles
2017 status:• Self-consistent coupling of core &pedestal theoretical models• Enables prediction and optimizationof ITER fusion gain: Q~12 possible
Profile Prediction (OMFIT, IPS, TRANSP,TGYRO using TGLF, NEO, EPED)(TGLF+NEO)

Meneghini Nucl. Fusion 2017,
Snyder Nucl. Fusion Award 201413

Romanelli Plasma Fus. Res 2014
Fig. 2 JINTRAC simulation of a JET-type discharge.

T. S. Taylor/NAS Committee/Aug 29, 2017

Major Advancement in Core Fluctuation Diagnostics Have
Enabled Detailed Validation of Fast Ion Transport Models
ECH modification of RSAEs in DIII-D

2004 status:• Alfven Eigenmodes andassociated transport observedand characterized

fTAE
fRSAE-min

fTAE
fRSAE-min Interplay of Sawteeth and AEs in JET1
EAEs

f (kHz)

EAEs

TAEs reduce
fast ionsLeads tosawtoothcrashTime (s)14

T. S. Taylor/NAS Committee/Aug 29, 20172017 status:• Fast-ion instability control tools
show promise• First principles simulations
reproduce measured modes &transport (MEGA)• Reduced predictive models
based on critical gradient

Van Zeeland Nucl. Fusion 2016
Y. Todo Nucl. Fusion 2016
Sharapov IAEA 2016

ASDEX-Upgrade obtained full ELM
ELM Suppression
Achieved
in Fully Non-Inductive
suppression with full
W wall matching
collisionality
shape
Hybrid DIII-D
Plasmawithand
Minimal
Impact on Performance•2004 status:

Demonstrates reliability for
extrapolation towards ITER

• Proof-of-principle demonstrations of RMP• Full RMP
ELM suppression
was
ELM suppression,pelletpacing, andQHobtained for >10s at KSTAR andmode~20 s at low rotation on EAST2017 status:•

Extension of all technique towards
ITER conditions
29•

Long-pulse ELM suppression•

I-mode developed,
QH-mode operation expanded•

Role of plasma response
and field penetration
Petty Nucl. Fusion 2017
Oh IAEA 2016
Sun IAEA 2016

15

KSTAR
3
161403"2
1.2"
Suppression ~ 10sI (MA)"
1 P
ECCD"
0.8"
0
NBCD"
0.4"
2
bootstrap"
Γ
0.0"
ion
0.2" Vsurf "
1
(V)"
0.0"
0

Paz-Soldan, EX/1-2 Kallenbach, OV/2-1
OV/2-4
B. Wan, OV/2-2
Hybrid scenario-0.2" Y.-K. Oh, DIII-D
4" Y. Sun, EX/P4-7
Nazikian PD/1-2

3"
2"
1"
0"
4" D
3" α
2"
1"
0"
0"

T. S. Taylor/NAS Committee/Aug 29, 2017

βN"

IRMP (kA)"
qmin"

1"

2"

3"
4"
Time (s)"5"6"Major New Understanding in SOL Heat Flux Channel
Width Developed Through Joint Experiments
2004 status:• Conflicting experimental data onheat flux width; large experimental
uncertainties

2017 status:• ITPA empirical scaling developed
setting potential challenge for 15
MA ITER discharges (λq ~ 1mm)•

High performance computing
enabling gyrokinetic simulations ofheat flux width•

New role of electron turbulencefound in simulations which may
significantly broaden heat flux
Goldston Nucl Fusion, 2012
Eich, Nucl. Fusion, 2013
Chang, Nucl. Fusion, 2017,16

T. S. Taylor/NAS Committee/Aug 29, 2017

Major Advances Have Been Made to UnderstandTungsten Behavior Under Extreme Conditions
2004 status:• Most devices favor low-Z wall for
plasma performance2017 status:• ITER to start operation withfull-W divertor••

JET ITER-like-wall (ILW) used tocharacterize tritium retention, fuelremoval, cracking, melting, dust,
plasma performance– Low T retention (0.3%)– Similar core confinement,pedestal Te reduced

ITER Divertor

Surface modifications (He-fuzz)
Litaudon Nucl. Fusion 2017
Baldwin Nucl. Fusion 2008

17

T. S. Taylor/NAS Committee/Aug 29, 2017

occurr

150

2.5% False Positive

Powerful Tools Have Been Developed to
Predict and Avoid Disruptions

100
50• Advanced
disruption warning systems predict oncoming disruptions
00
200 disruptions
400
600– NSTX:> 96%
caught, < 3% false alarm
Warning Time, tquench-twarn [ms]– JET: > 98% disruptions caught, < 1% false alarm
250

occurrence

200
150
100

(b)

6 Level Warning Rule
5 points: 0.9% Late+Missed
14.2% False Positive
10 points: 3.7% Late+Missed
2.8% False Positive

A. Murari, ITPAMHD (2013)

S. Gerhardt Nucl.
Fusion 2013

50
0
0
200
400
600
Warning Time, tquench-twarn [ms]gure 7. Histograms of warning times. (a) shows the statistical
Extensive
suitewhileof disruption
ults•of thethree-level tests,(b) shows the avoidance
results of the techniques-level test.

– NTM control by ECCD, MHD instability control, MHD spectroscopy

rning fraction is approximately 1%, while the false-positivee is still high at 14%. However, increasing the warning level
T. S. Taylor/NAS Committee/Aug 29, 201718
10 points, which only occurs when more than a single test

Strong Progress in Explaining Fast Dissipationof ‘Runaway’ Electrons at Plasma Termination2017 status:• Simulations capture underlying
dissipation mechanisms• Dominant RE seed processes
discovered (hot tail)• RE control developed
Strong U.S. focus• Experiment• SciDAC SCREAM• BPO task group• ORNL/DIII-D
pellets

AnomalouslyhighdissipationNew
impurities
model

Shatteredpellet

DIII-D19

γ raycameraIncreaseddissipation

2004 status:• Critical electric field quantified,additional terms starting to be
explored

ITER
T. S. Taylor/NAS Committee/Aug 29, 2017

Paz-Soldan PRL 2017
Hesslow PRL 2017

Progress Since the 2004 Burning Plasma Report Has
Strengthened Our Confidence in BP Performance
Topic (example)

2004

2017

ITER Operational
Scenarios

Isolated examples of
performance, high rotation, ion
heating• Integrated solutions• Extended toward ITER conditions(low rotation, e-heating)• JET ILW

Pedestal

Peeling-ballooning theory
developed• Predictive model of pedestal
performance validated against
experiments

Energetic particles

AEs observed, basic mode
properties and associatedtransport characterized• Advanced fluctuation and fast ion
distribution measurements• First gyro-kinetic simulations
reproduce measurements• Reduced predictive models basedon critical gradient

Disruption
mitigation andavoidance

Massive gas injection for fast
• SPI technique
shutdown, limited capabilities on • Understanding of radiation
disruption avoidance &asymmetries
mitigation characterization• Real-time stability calculations &disruption predictors

20

T. S. Taylor/NAS Committee/Aug 29, 2017

Progress Since the 2004 Burning Plasma Report Has
Strengthened Our Confidence in BP Performance
Topic (example)

2004

2017

Runaway electrons Critical electric field quantified +other terms being explored• Simulations capture underlying
dissipation mechanisms• RE control developed

ELM control

Proof-of-principle demonstrationsof RMP ELM suppression, pellet
pacing, and QH-mode• Extension towards ITER
conditions• Understanding of stability limits

Error Fields

Simple vacuum fieldunderstanding• Predictive models with plasma
response and field penetration

Transport

Gyrokinetic codes and reduced
transport models being
developed• Multi-field, multi-scale simulations
compared with data
• Improved fidelity reduced models

Integrated
modeling

Manually intensive “Herculean”
simulations. Missing firstprinciple pedestal model, rotationetc• General frameworks developed for
streamlined integrated workflows• High fidelity models using highperformance computing

21

T. S. Taylor/NAS Committee/Aug 29, 2017

Progress Since the 2004 Burning Plasma Report Has
Strengthened Our Confidence in BP Performance
Topic (example)

2004

2017

Plasma control

Feedback control of 0D plasma
parameters• Profile control• Offline control developed bysimulation

Divertor power
handling

Demonstration of heat flux
reduction in low-Z tokamaks• Extended to metal walls• Feedback control of divertor heatflux

SOL heat flux
width

Conflicting experimental data on • ITPA empirical scaling developed
heat flux width• New role of electron turbulence
predicted in gyrokinetic simulations

Divertor geometryStandard configurations withlimited poloidal flux expansion• Advanced divertor configurations
with increased poloidal/toroidal flux
expansion

PMI

Individual research on local
surface, global migration, SOL
transport• Integrated studies between core/edge/wall• Mixed wall and ITER-like wallmaterial studies

22

T. S. Taylor/NAS Committee/Aug 29, 2017

Status of World-Wide Research
That Supports Burning Plasma Science
Executive Summary:• The world program is focused on preparing for burning plasmas in ITER
• ITER has been highly effective as a forcing function for driving progressin fusion science and technology.
• World tokamak program is well positioned to address any emerging
issues with regard to ITER operations and successful attainment of Q=10
• U.S. facilities are highly capable research platforms for innovation andunderstanding

23

T. S. Taylor/NAS Committee/Aug 29, 2017

The World Program Is Focused on
Preparing for Burning Plasmas in ITERJET

DIII-DASDEX-U

MAST-UITER

NSTX-U

WEST

TCV

SST-1

EAST

JT-60SA

KSTAR

U.S. is a major contributor, and benefits greatly from participation
24

1706-0101/ 24

T. S. Taylor/NAS Committee/Aug 29, 2017

The World Program Is Focused on
Preparing for Burning Plasmas in ITERJETASDEX-U

MAST-UITER

JT-60SAInternational partners provide• Stronger scientific basis• Broad team, range of facilities,
tools, and experience• Industrial fabrication capabilities• Shared costs

DIII-D

NSTX-U

WEST

TCV

SST-1

EAST

KSTAR

U.S. is a major contributor, and benefits greatly from participation
25

1706-0101/ 25

T. S. Taylor/NAS Committee/Aug 29, 2017

The World Fusion Community is Organized toCarry Out Burning Plasma Research• International Tokamak Physics Activity (ITPA) makes key contributions tocoordinating worldwide burning plasma research through joint
experiments on multiple devices– ~ 850 scientists from all 7 ITER parties (US, China, EU, India, Japan, Korea, Russia)
plus Australia– 7 Topical Groups focus research in key areas•

Diagnostics, Divertor-Scrape-Off-Layer, Energetic Particles, Magnetohydrodynamic Instabilities,
Pedestal & Edge Physics, Transport and Confinement, Integrated Operating Scenaros– Semi-annual meetings convene 30-40 members and other experts• State of the art burning plasma research discussed• Multi-machine joint research proposals generated• Recommendations for ITER generated– Over 100 refereed journal publications produced directly from ITPA topics inlast 5 years• The US plays a substantial role in ITPA experiments and documentation
activities– Over 200 US scientists
26

T. S. Taylor/NAS Committee/Aug 29, 2017

ITPA Success Story: ELM Suppression by Magnetic
Perturbations Verified on US and EU Tokamaks•

ELM Suppression using internal coils on DIII-D initially formed the basis for adding 3D
coils to the ITER design•

ITPA Joint Experiment organized to reproduce ELM suppression on other tokamaks•

DIII-D and ASDEX-Upgrade joint experiment led to the first observation1-3 of ELM
suppression in AUG, confirming basis for ITER

1. R. Nazikian, W. Suttrop et al. Proc. 26th IAEA Fusion Energy Conf., Kyoto, Japan (2016), to be submitted to Nuc. Fusion
2. W. Suttrop, R. Nazikian et al., submitted to Phys. Rev. Lett. (Nov 2016)
3. W. Suttrop, R. Nazikian et al., Proc 44th European Phs. Soc. Conf., Belfast, N. Ireland (July 2017), to be submitted to Plas.
Phys. Control. Fusion
27

T. S. Taylor/NAS Committee/Aug 29, 2017

ITER Project is Coordinating Additional
Research Activities Involving World Community• ITER Research Plan
– Developed in collaboration with community experts worldwide, this document
outlines the anticipated content and schedule for research activities on ITER

• ITER Integrated Modeling Expert Group– Help guide the ITER integrated modeling program and to act as an interface
between member physics modeling programs and the ITER organization.

• ITER Scientist Fellow– Prepare for the scientific exploitation phase of the device by strengthening the
involvement of the fusion community directly with ITER. Interact closely with the
ITER Science & Operations Department in the definition of a research program• ITER Operations Network– Provide advice and feedback to the ITER project in the Operations area…”

28

T. S. Taylor/NAS Committee/Aug 29, 2017

Complementarity/Uniqueness of World Tokamak Facilities
Continue to Advance Fusion Toward Burning Plasmas••

Tokamak

Key Contributions to Burning Plasma
ScienceComplementarity enables multiplatform development andevaluation of key physics

DIII-D

Scenarios, transients, control, EPs

NSTX-U

Low R/a physics, EPs, transients

JET

Tritium, size scaling, ITER-like wall

Uniqueness promotes evaluation of
new ideas that emerge fromsynergistic collaborations acrossfacilities

AUG

Transport, divertor, tungsten wall

TCV

Shaping effects on core and divertor

MAST-U

Low R/a physics, advanced divertor

WEST

Long-pulse tungsten divertor

EAST

Long-pulse scenarios, core/edge
compatibility, metal walls

KSTAR

Long-pulse physics, 3D fields, H&CD
technology

JT-60SA*

H&CD technologies, advanced
scenario demonstration

ITER*

Integrated burning plasma
demonstration

Well positioned to advance burning
plasma science in preparation for andin concert with ITER

*under construction
29

T. S. Taylor/NAS Committee/Aug 29, 2017

U.S. Facilities: Excellent, Cost-Effective Research Tools
to Provide World-Leading Fusion Science

DIII-D•

NSTX-U

DIII-D and NSTX-U provide world-leading and complementary capabilities toresolve scientific Issues for fusion energy– Mature facilities with established infrastructure and experienced staff– Highly flexible, 2D shaping, controlled 3D magnetic perturbations,– Well diagnosed: in-depth scientific investigations and model validation– Divertor structures top and bottom, easily modified– National and international research teams– Low vs high torque and ρe– Complementary current drive (ECCD, Helicon vs HHFW, helicity injection)– Complementary boundary approach (cryopump vs lithium, solid vs liquid)

Train the next generation of scientists and engineers
30

T. S. Taylor/NAS Committee/Aug 29, 2017

US Theory and SciDAC Burning-Plasma Research: Rapid
World-Leading Advances in Predictive Capability• Develop and support world-class numerical tools
–
–
–
–
–
–

GYRO, GS2, GTC, GEM: electromag. turbulence
M3D-C1, NIMROD; nonlinear extended MHD
BOUT, ELITE, XGC1, COGENT, UEDGE: bound. & PMI
TGLF, NEO, EPED: core/pedestal prediction
OMFIT, TRANSP, ISP: integrated simulation
AORSA, NuBEAM, CQL3D: RF sources

EPED Super H-Mode Prediction
Theory ! experiment• Address important burning plasma issues– Performance prediction with coupled core &––––pedestal à higher confidence, optimization
Pedestal transport and L-H transiton
Plasma response to 3D fields àELM suppression
Simulation of RE dynamics and disruption
mitigation scenarios
Critical gradient and resonance broadening
EP transport models

Multi-Scale Turbulence (GYRO)

GYRO δTe/Te0

electron scale• Strong U.S. partnership between theory & experiment– Model validation– Interpret, direct, and predict experimentàdiscovery and innovation in fusion research

31

T. S. Taylor/NAS Committee/Aug 29, 2017

ion scaleU.S. Leadership In Burning Plasma Research
Evidenced By Nuclear Fusion Prize Recipients (won 8 of 11)
Luce, Scenarios, 2006

Evans, ELM Suppression, 2008

Diamond, Rotation Theory,
2012

Rice, Intrinsic
Rotation, 2010

Snyder, Pedestal, 2014

Whyte, Scenarios, 201332

Sabbagh, Stability, 2009

T. S. Taylor/NAS Committee/Aug 29, 2017

Goldston, SOL physics, 2015

Strategic Elements to Strengthen or
Accelerate U.S. Burning Plasma Research
Executive Summary:• Realizing fusion energy within the next several decades will require
increased funding and reduced costs.
• ITER provides the most timely and capable option for the U.S to exploit
burning plasmas.
• The U.S. should develop a strategic plan with exciting stage milestones
targeting a U.S. cost-attractive DEMO in the next several decades• Fusion energy development requires an increasing effort in fusionmaterials and fusion nuclear science

Strategic elements in mostly considering the United states is a partner in ITER
33

T. S. Taylor/NAS Committee/Aug 29, 2017Electricity Demand in Next 100 Years Presents Major
Challenges and Also Tremendous Opportunity*Message AMPERE2-450-FullTech-OPT Scenario•

Integrated emissions limited tomaintain CO2 levels below 450
ppm , full technology

Projected need for ~ 35,000
GW from non-CO2 producing
sources

35,000 1 GW-e plants !!!

•Strategic Interestfor the U.S. and the World
34

Consequently, annual
investment in energy
projected to explode- $0.8T by 2050
- $2.5T by 2100

! Timely positioning is key

T. S. Taylor/NAS Committee/Aug 29, 2017

Substantive Progress Towards Fusion Energy Requiresa) Increased Funding and/or b) Reduced Costs
International partners are needed
to develop fusion energy

Koepke, 2014
35

T. S. Taylor/NAS Committee/Aug 29, 2017

What is Required to Increase Funding• Provide an exciting vision for the future to motivate increased public
and political support, funding and attract the brightest and best
researchers• Work to unify the community, get the community working together– Requires community leadership and engagement, perhaps a processsimilar to that of 1998 - 2004

• Establish a partnership between the Feds (OFES, OS) and thecommunity• Resolve to maintain a strong U.S. commitment to the path forward• Engage the entire U.S. fusion community in burning plasma research:planning, preparing, and execution.
– Community must own the path forward as their path forward– Required to maintain community unity and commitment• Recommendation: FES and the U.S fusion community should begin aprocess to develop a roadmap and strategic plan
36

T. S. Taylor/NAS Committee/Aug 29, 2017

Accelerating the Path to Burning Plasmas andFusion Energy Development

Ages-old quip: “Fusion is 50 years away and always will be.”How toreconcile?
NAS charge: “given that economical fusion energy within
the next several decades is a U.S. strategic interest”

37

T. S. Taylor/NAS Committee/Aug 29, 2017

Accelerating the Path to Burning Plasmas andFusion Energy Development•

The Challenge– Very challenging problem à Robust funding required– Multiple challenges must be resolvedà Strategic plan required– Staging of elements essential à Community consensus needed
Ages-old quip: “Fusion is 50 years away and always will be.”How toreconcile?
NAS charge: “given that economical fusion energy within
the next several decades is a U.S. strategic interest”

38

T. S. Taylor/NAS Committee/Aug 29, 2017

Accelerating the Path to Burning Plasmas andFusion Energy Development•

The Challenge– Very challenging problem à Robust funding required– Multiple challenges must be resolvedà Strategic plan required– Staging of elements essential à Community consensus needed
Ages-old quip: “Fusion is 50 years away and always will be.”How toreconcile?
NAS charge: “given that economical fusion energy within
the next several decades is a U.S. strategic interest”•

The Solution– Compelling vision for energy mission à Increase available funding– Vetted strategic plan à Inform prioritization of available funding– Broad community consensus à Unified purpose and messaging– Bold leadership à Implement & execute difficult priority choices--- All done in partnership with Office of Science and FES ---39

T. S. Taylor/NAS Committee/Aug 29, 2017

Accelerating the Path to Burning Plasmas andFusion Energy Development•

The Challenge– Very challenging problem à Robust funding required– Multiple challenges must be resolvedà Strategic plan required– Staging of elements essential à Community consensus needed
Ages-old quip: “Fusion is 50 years away and always will be.”How toreconcile?
NAS charge: “given that economical fusion energy within
the next several decades is a U.S. strategic interest”•

The Solution– Compelling program vision à Increase available funding
My
recommendation:– Well informed strategic plan à Inform prioritization of available funding•– Fully
ITER as the
U.S. Burning
PlasmaExperiment
Broadparticipate
community inconsensus
à Unified
purposeand messaging•

40

Developa strategicplan withwith
exciting
milestones
targeting--- All donein partnership
Officestagedof Scienceand FES--a U.S. cost-attractive DEMO in the next several decades

T. S. Taylor/NAS Committee/Aug 29, 2017

U.S. Should Fully Participate in ITER as theMost Direct and Fastest Path to a Burning Plasma
Observations• All fusion programs worldwide have chosen ITER as the most expedient means toburning plasmas on their path to fusion energy development
ü Broad consensus on goals, responsibilities, and ownershipü Broad worldwide participation in burning plasma research•

The framework for pursuing a project of this magnitude is now in place withestablished management, design and construction teams; infrastructure;
nuclear license…
ü Established mechanisms for timely resolution of emerging issues•

ITER construction is progressing rapidly under new management
ü Clear communication, responsibility, and accountability structure•

Planning and preparation for operations and exploitation are beginning

These efforts/activities take time and money
Recommendation: Fully fund U.S. contributions to ITER
– Guarantee on-time, on-spec delivery of U.S. in-kind contributions– Enable ITER IO to address emerging issues in timely, efficient manner– Expand breadth of U.S. community efforts in burning plasma research
41

T. S. Taylor/NAS Committee/Aug 29, 2017

Strategic Plan
Assertions and Principles
Assertions••••

Burning plasma R&D is the next major step for fusion development
ITER represents the most timely, capable option for a U.S. burning plasma
experiment
Materials and nuclear science challenge is formidable and early resolution of key
challenges is critical for timely delivery of fusion energy
Tokamak is the most expedient path to fusion energy

Principles
•
•
•
•
•
•

42

Enable development of attractive fusion energy as soon as possible
Timeliness over attractiveness of end product (power plant)
Build on existing strengths
Maintain high level of scientific excellence
Value innovation
Leverage capabilities of international partners

T. S. Taylor/NAS Committee/Aug 29, 2017

Realization of Attractive DEMO Will Require Closing the
Feasibility Gap in Three Areas Required for Fusion Energy** Priorities, Gaps,
Opportunities … 2004

Fusion Power
Source (Neutrons)

A successful burning plasma experimentwill leave significant gaps in fusionmaterials and blankets

Materials
for Fusion
Environment
DEMO

Harnessing
Fusion Power

43

Approximate Technical
Readiness Level

T. S. Taylor/NAS Committee/Aug 29, 2017

Developing Key Elements of a Strategic Plan•

Support a significant community effort to provide a more in-depth evaluation ofopportunities for a more cost attractive DEMO or power plant. (systems studies)– Define domestic R&D needed to validate opportunities•

Support a community/FES process (follow-on to present community workshops) todevelop a long term fusion strategy/roadmap targeting a U.S. cost-attractive DEMOin the next several decades.
– Include exciting staged milestones•

Strategy should include– Robust support for engaging in burning plasma physics– Plans for solid foundational physics; engaging universities, industry,and national labs
– A strong theory and computation program– Plans for new U.S. fusion facilities– Plan (how/when) to transition from existing facilities to new facilities– A growing effort in fusion material development and testing– A growing effort in developing fusion blanket research

Challenge: broad effort is needed, requiring significant funding➜ Difficult priority choices are required
44

T. S. Taylor/NAS Committee/Aug 29, 2017

The U.S. Strategic Plan Must Include
a Robust Tokamak Effort•

To support and prepare for burning plasma research (ITER)! exploitation•

To prepare for a cost effective DEMO•

To train fusion scientists and engineers for the future

Key elements of a tokamak program should include•

Plasma exhaust (divertor, materials)•

Disruption prediction and avoidance•

Steady-state•Predictive capability•

Optimize performance (nTτ/RB)– Proposals for cost effective Demos include significantly improved
confinement (~ 1.6 - 1.8) and stability.

•

Enabling Technologies– Magnet Development program -> demonstrate large, high field magnet
with high temperature superconductors– Current drive?

Facility: new tokamak facility or upgrade of existing facility
45

T. S. Taylor/NAS Committee/Aug 29, 2017

A Growing Effort in Fusion Materials and Fusion Nuclear
Science is Required to Advance Fusion Energy• Materials– Develop new materials (BES: materials by design); plasma facing, structural– Test materials in a plasma environment• Linear devices, such as MPEX
• Fusion facility environment (tokamak, …) effect of material response on plasma
performance is critically important– Test material in high energy neutron environment• Gap in the world program• Potential opportunity for cost effective volume neutron source (Gas dynamicTrap), or integrated nuclear science test facility (FNSF)• Fusion Blankets– Propose next step is a multi-effect, non-nuclear blanket test facility– Develop a long term strategy and plan for U.S. fusion blanket development,in the context of the international program.

• We will require a growing workforce of scientists and engineers withexpertise in materials and fusion nuclear science

46

T. S. Taylor/NAS Committee/Aug 29, 2017

Summary
Burning plasmas are thenext step in fusion energy
development

Recommended Actions:Reaffirm previous panel
reports stressing theimportance ofburning plasmas
47

ITER represents a unique
opportunity for the U.S. topursue burning plasmas

Feasibility gaps in materials
and blanket technology
offer rich scientificopportunities

Capitalize on thesubstantial human,
technical and fiscal
investment made in ITER

Develop a strategic planwith exciting staged
milestones leading to a
cost-attractive DEMO

T. S. Taylor/NAS Committee/Aug 29, 2017