Strategic Plan for Burning Plasma
ResearchR. J. Hawryluk and M. C. Zarnstorﬀ
presented to:
NaConal Academy of Science CommiEee
Dec. 15, 2017

Fusion Performance Has Increased SubstanCally UnCl 1997
Exis%ng experiments have achieved
Gain = QDT ~ 0.6• JET and TFTR have produced DTfusion powers >10MW for ~1s• ITER is designed to a scale whichshould yield QDT ≥ 10 at a fusion
power of 400 – 500 MW for 300 –500 s•• Progress has been determined by:• Scien%ﬁc advances• Larger more powerful facili%es•
2Need the next generaCon offaciliCes to make progress toburning plasmas

DEMOITER

Gain = Q =Fusion Power~ niTiτ EInput PowerITER Will Enable the Understandingof Burning Plasmas•

Understanding of:• Sustaining hot burning plasma by alphapar%cles• Conﬁnement of reactor-scale plasma• Stability from micro to macro in burning
plasmas• Plasma wall interac%ons at high heat ﬂux• High gain dynamics

3• Nonlinear interac%on of turbulence, wall-interac%on, external sources, fusion reac%vity,
macroscopic instabili%es.
• Strong coupling between the plasma and “external” systems especially plasma-wallinterac%ons

ITER is Developing Reactor Relevant Technology That
Relies on Large IntegraCon Eﬀort••••

4First wall materials
Superconduc%ng magnets
Remote handling
Tests of breeding blankets(at modest neutron ﬂuence)Superconduc%ng model
Central Solenoid Coil

• Progress in burning plasma research and fusion development relies
on integra%on of cubng edge physics and technology.
• ITER provides a unique opportunity to study burning plasmas• Integra(on issues are complex and will never be captured in thepublished literatureInternaConal Community Is ShiZing Focus toAZer ITER
• ITER, while a very important step in developing fusion, is not
the ﬁnal step toward a power plant• Important scien%ﬁc and technological ques%ons remain• In addi%on, cost issues for both future burning plasma experiments
and the produc%on of electricity have to be addressed• Major design and R&D studies are underway in most of theITER partners for the steps beyond ITER
5

Outstanding ScienCﬁc and Technical Challenges
Beyond ITER
ScienCﬁc Challenges•Improve plasma conﬁnement•Improve shaping, control• Simplifying, reducing size

Increase plasma stability andsustainability• The plasma-material interface:• eﬀect of plasma on materials• eﬀect of materials on plasma•

6

Technical Challenges• Harnessing fusion power• durable materials in fusion
neutron ﬂux,
• power extrac%on•

Tri%um Breeding Ra%o >1•

Increase magne%c ﬁeld and current
density
Improve economic performance•European Fusion Roadmap:
Put Electricity on the Grid Mid-Century•

Vision of a demonstra%onplant is deﬁned largely byITER• Ini%ally pulsed opera%on• Substan%al technological
R&D program•

7Construc%on schedule is setby ITER results

A.Donné presented in Beijing, Nov. 2017, to be issued in the spring 2018

China is Embarking on a More Aggressive Path
• China’s Ministry (MOST) is funding the next step of China Fusion
Engineering Test Reactor (CFETR)• Relies heavily on ITER technology but goes beyond ITER
• Exploring higher ﬁeld and possibly high temperature superconductors• Steady state opera%on (200 MWe to 500MWe)• Tri%um breeding• Timeline is not %ed directly into ITER’s• PPPL par%cipates in both CFETR and South Korean DEMO studies

8

CFETR Design Takes Advantage of Work Done on ITER
and Strong R&D Program to Address Speciﬁc Issues•

EAST results and ITER
procurement arrangements
support both ITER and CFETR•

CFETR R&D includes work on:
••
•
•
•

•
9Vacuum vessel
High Tc (?) central solenoid
Advanced divertor
Breeding blanket
Tri%um system

Goal is demonstrate TBR>1
and produce electricity

Different Perspectives Exist on the Future Direction ofTokamak Research
US research has pioneered theopera%onal boundaries• Op%ons under discussion includepulsed/steady state, high βT/ highβp (q95)•Diﬀerences in perspec%ve reﬂect
integra%on assump%ons:• Current drive eﬃciency• Magnitude of ﬁeld
• Power ﬂux assump%ons•

US studies have emphasized cost(high performance) and steadystate

q95=3
ε

βT
(1+ k 2 ) / 2

0.6

0.4

CREST

Current limit•

ACT1
SLIM-CS

EU-SS

K-DEMO 2

EU-DEMOpulsed ITER-SS K-DEMO 1

CFETR

0.2

0.5

βN ~5

q95=8ACT2

βN =30.60.7

εβP

What are the US’ roles in burning plasma researchand fusion energy development?
•The road to fusion energy is a long one with other countries stepping
forward to take the lead
• Unless there is a radical redirec%on in US funding, work on burning plasma andfusion energy development will have to done interna%onally•

To make an impact, US needs to be driving innova%on based on strong
scien%ﬁc understanding• Iden%fy key scien%ﬁc and technical solu%ons to the challenges for ITER andbeyond to:• Establish the scien%ﬁc and technical viability and• Reduce the cost for fusion development and fusion energy

11• PPPL aims to extend this understanding to burning plasmas
and use it for innovaCon

On-going examples how PPPL Contributes toUnderstanding and InnovaCon• NSTX-U: high-β compact conﬁgura%on• Develop predic%ve understanding of burning plasma• Robust power and par%cle exhaust solu%on

12Fusion Technology and Performance

NSTX-U Pursues TransformaCve Ideas
to Accelerate Fusion Development

13ST =Spherical
Torus.
A magnetic
confinement
configurationthat can lead toa smaller andmore costcompetitive
fusion energy
reactor.

ST-based fusion neutron source
Provide steady-state fusion neutron
environment for nuclear material andcomponent R&D

ST Pilot Plant for net electricity
Liquid metal blankets for high thermal
efficiency and high–temperature
superconducting coils

NSTX Upgrade Facility and Research Program
Extend ST confinement understanding tofusion-relevant temperatures

Demonstratesustainment
for future
steady-state
operation

Advanced diagnostics + computation
provide fundamental understanding andbasis for next-step ST devices

NSTX Explored ST stability and confinement
Fundamental Plasma and Materials Science

High-power NSTX-U
tests of liquid metals astransformative wall solution

Exascale Project Oﬀers Path to High Fidelity
Whole Device Model••14First step is to integrate core with edge
Design of new facili%es and planning on burning plasma experiments will require
whole device models

Develop Robust Power and ParCcle Exhaust SoluCon
CompaCble with High Performance
Liquid metal boundary is a poten%al
solu%on to two challenges:• Self-healing and may be a robust ﬁrst
wall of a burning plasma• Increased plasma conﬁnement
and pressure
Current ac%vi%es:• PPPL’s LTX-β• EAST (China)• Long term plan for full liquid boundary
in NSTX-U•15 Vapor metal concepts

PPPL LTX-β

3D MagneCc Shaping for Minimal RecirculaCng Powerand Enhanced Stability
Oﬀer methods to transform the approach tofusion energy• Elimina%on of large-scale instabili%es andtermina%on events• Increased plasma sustainment eﬃciency• Improved pressure limits• Reduced turbulence• Wendelstein 7-X (W7-X) goal is sustained 5% beta
and validate stellarator op%miza%on• Already demonstrated Te = 10keV• Op%miza%on of stellarator performance has agreat deal of poten%al•

16

W 7-X

Validated in Experiment !
Even Small 3-D
MagneCc Fields Have Big Eﬀects!

• Control of plasma
stability using small
3-D magne%c ﬁelds
at edge• Quan%ta%ve
valida%on oftheore%cal modelfor edge instabili%es• Disrup%on
threshold also
validated

IPEC Prediction of stability
SpaceSuppressio
Locking
Suppression
nthreshold
thresholdthresholdmet
exceededmet

Are there magne%c conﬁgura%ons with small 3-D ﬁelds that canimprove the performance of tokamaks and decrease the cost of thestellarator coils?
1517Experimental Validation ofModel

access to“hiddenwindow”
Non-resonant 3D
perturbations

Strategic Approach to Burning Plasma Research• US decided in 1996 to pursue burning plasma interna%onally• US has an advantageous opportunity to par%cipate in ITER to address keyissues• Involvement in ITER needs to include universi%es, industry and na%onal labs
• For US to be eﬀec%vely involved in ITER, need a strong domes%c program• If US were to withdraw from ITER, US program needs to increase focuson innova%ons• Withdrawal from ITER will undermine interna%onal collabora%on• A decision for the US to do everything in fusion R&D suppor%ng DT burning
plasmas would require a major ﬁnancial commitment• Need to determine if innova%ons can substan%ally reduce the costs andovercome the impact of going it alone to study burning plasmas in the US18

Breakthrough InnovaCons and Detailed
Understanding PosiCons US Strategically• If US par%cipates in ITER:• Enables us to exploit ITER eﬀec%vely and transfer the knowledge to US• Breakthrough innova%ons posi%on the US industry to follow up onITER’s success in the next step of fusion energy development• If US does not par%cipate in ITER:• Breakthrough innova%ons may open a pathway to a burning plasmathat is consistent with constrained budgets. Examples include:19• Prac%cal high temperature superconduc%ng magnets• High conﬁnement at high β & low collisionality in NSTX-U• Sustained β=5% in W7X without disrup%ons• Enhanced sustained pedestal conﬁnement• Liquid-PFC/divertor enabling higher heat-ﬂux systems

US Fusion Strategy Needs to be Robust• Needs to make major breakout contribu%ons at all budgetlevels• The US community needs to make the case that we cansuccessfully address the scien%ﬁc and technical challenges todeliver on an energy program• Need to posi%on ourselves to take advantage of acommitment to develop fusion energy20• Na%onally or interna%onally