Plasma Science & Fusion Center

The Road Not Taken* --- Yet
D. Whyte, for	MIT Plasma Science & Fusion Center

NAS CommitteeStrategic Plan for U.S. Burning Plasma Research	Austin, TX	

December 2017	

* with sincere apologies to R. Frost	

Whyte, USMFRSD, 07/17	1	1) long-term strategic plans for national program ofburning plasma science?	

Presently•Insufficient diversification in approaches	•Stagnated innovation in science/technology  incrementalism	

•US program is missing strategic opportunitites for leadership	

Could be•Leveraging present thought-leadership in US	

•Program that stands in contrast to “locked-step” international
scene	

 Higher risk tolerance	 Innovative	 US-defined economic targets	

Whyte, NAS, 12/17	2	2) the potential impact on this plan if the U.S. is, oris not, a partner in the ITER project?	

ITER decision	

In	Out	Whyte, NAS, 12/17	

Pros	

Challenges	

Leveraged investment	

Out-leveraged by $$	

Known technology	

40-year old tech at burn	

Known timeline	> 20 years, slow!	

Partnered	Not leading	

Take lead	

Lost trust /w partners	

Forced to innovate	Unknown timeline + tech	

Free to innovate	

Tolerate higher risk	3	2) the potential impact on this plan if the U.S. is, oris not, a partner in the ITER project?	

ITER decision	

Not ours tomake!	

Pros	Challenges	

Leveraged investment	

Out-leveraged	

Known technology	

40-year old tech at burn	

Known timeline	> 20 years, too slow	

Partnered	

Not leading	

Take lead	

Lost trust /w partners	

Forced to innovate	Unknown timeline + tech	

Free to innovate	

Tolerate higher risk	

Plan must be robust to decision  US fusion energy goals	

Whyte, NAS, 12/17	

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(3) the vision and plan for MIT's Plasma Science and Fusion Center inthe pursuit of fusion energy science(4) any strategic elements that might strengthen or accelerate U.S.
research in burning plasma science given that economical fusion energy
within the next several decades is a U.S. strategic interest	

•Reinvigorated US leadership, leveraging a newly available
science and technology toolkit 
•Enabling cost-effective diversity and innovation in fusion andplasma sciences •Accelerated path towards US-led vision of economicallycompetetive fusion energy that considers	 Climate change timeline; deep decarbonization needed by 2050	

 A rapidly evolving energy marketplace	 Making fusion a part of the conversation in this new energy
landscape	

Whyte, NAS, 12/17	

5	

Reminder: NAS sanctioned more than a single
pathway to burning plasmas	

Whyte, NAS, 12/17	

6	

ITER and FIRE addressed same physics, with same
assumptions; vast difference in scale due to single
technology design choice	

pth! E ~ R 2.7 B 5.5

Volume ~ R3~ 1/B5	

Cryogenic	

Copper	Whyte, NAS, 12/17	

Nb-Sn	

Superconductor	

FIRE	

ITER	

B (T)	

10	

5.3	R (m)	

2.14	

6.2	

Q	10	10	τ / τCR	> 1	> 1	Vp (m3)	

30	800	25x	7	Choosing ONLY the low-field, large volume path
now appears to have severe strategic disadvantages	

• 40-year gap!

[atm×s]10• A single
experiment in theentire world!	

 Fusion is too
important to rely
on a single
project/concept	

historic progress towards net energy
D-T breakeven (Q=1)
ITER (projected)

1
0.1
0.01
0.001

• Technology &science probably
evolve in 20-30years?	

Whyte, NAS, 12/17	

0.0001
1960 1970 1980 1990 2000 2010 2020 2030 2040

8	

“Two roads diverged in a yellow wood”	

High-Field +	Compact	

Low-Field +	Large	

Whyte, NAS, 12/17	

9	

How did we get here?
He who ignores history..	

Technical vs programmatic vs politicalconstraints	

“Dead end technology”	

Perception of where you are going ‒ 
for your sponsor “perception is reality”	

Certain scale ($$, time) necessarily leadto deep politicization of decisions	Whyte, NAS, 12/17	

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Was your 2003 version correct? YESHigh-B field path is viable and attractive	

Issue	

Scaling	Issue	

Power density	

B4	

Confinement (generic)	

R2 B2	

Confinement(tokamak)	

Confinement(stellarator)	

Gain	

Stable pedestal/I-mode	Whyte, NAS, 12/17	

R2.7 B3.5!		

!		

(H98)	

R3.1 B2.1 (Petty) 	 !		

R2.8 B2.1	

Density (stellarator)	

!		

R-1 B1	!		

β B2.5 (burning)	 !		

Heat exhaust: min. fZ	

R1.3 B0.9 	

Heat exhaust: q//	B-1 (burning)	

Runaway e- amp.	

exp (R0.28 / B0.3)	

!		

R2-3.1 B4-5.5	 !		

~ βN B2	

Density (tokamak)	

Scaling	Synchrotron: runaways	

B2	

Synchrotron:thermal	

~B1.5	TAE	!		

!		

n~B, vA~B	 !		

11	In fact they were more correct than they
could have known!	

Issue	

Scaling	Issue	Power density	

B4	

Confinement (generic)	

R2 B2	

R2.7 B3.5

Confinement(tokamak)	

Confinement(stellarator)	

!		

(H98)	

R3.11998	

B2.1 (Petty) 	 !		

2008	

Gain	

Stable pedestal/I-mode	

2010	

Whyte, NAS, 12/17	

!		

2005	!		

R2-3.1 B4-5.5	 !		

~ βN B2	

2016	

!		

R-1 B1	

Density (tokamak)	

Heat exhaust: min. fZ	

Heat exhaust: q//	R1.3 B0.9 	

2010-17	

B-1 (burning)	

TAE	

!		

exp (R0.28 / B0.3)	

2005-17	

B2	

Synchrotron: runaways	

Synchrotron:thermal	!		

β B2.5 (burning)	 !		

Density (stellarator)	

Runaway e- amp.	

R2.8 B2.1	

Scaling	!		

~B1.5	

n~B, vA~B	 !		

12	

Oh boy, here we go, HTS will save us all, yada, yada
Send lots of money to MIT..NO	• Debate is NOT: 	

• ITER vs. not ITER	

• tokamak vs. stellarator	

• HTS vs NbSn, etc.	

• The debate is about slow & incremental vs. rapid & innovative	The hard truths of innovation	

- Difficult/impossible to incorporate into large, decadal+ projects	

- Often end up demonstrating (ISS) or abandoning (HumanGenome Project) obsolete technologies	- Require stomach for risk	Whyte, NAS, 12/17	

13	

“Two roads diverged in a yellow wood”	

Less-trodden	Innovative	

Leadership	Well-trodden	

Conservative	

Coalition	

Whyte, NAS, 12/17	

14	

The science death spiral of having a
single mega-project “road”	

Single device must satisfy all	constituents	

Increased scope	More conservatism 	

Innovation cannot	

be adapted 	

Takes longer	

Costs more	

Whyte, NAS, 12/17	

15	

“Two roads diverged in a yellow woodAnd sorry I could not travel both”	

2060?	

2040	Whyte, NAS, 12/17	

16	

“The one less travelled by”	?	

Whyte, NAS, 12/17	

17	The virtuous circle of the high-field compact “road”	

Smaller devices to 	access new science	

Focussed constituents	

Faster	Cheaper	

Science & technology	

Innovation leveraged	

Diverse missions	Diverse approaches	

Whyte, NAS, 12/17	18	

High-Temperature (HTS) superconductors is an
example of leveraging revolutionary technology
developed outside fusion	Commerically	Available tapes	Jc ! B $=J c, 0 #" B0 &%'(Jc0	B0	α	

Nb-Ti	

103	5	3	

Nb3-Sn	103	

10	3	REBCO	

2.5x103	5	0.6	

T~4 K, B>B0	Whyte, NAS, 12/17	19	

High-Temperature (HTS) superconductors is anexample of leveraging revolutionary technology
developed outside fusion	

ARC	

Q~13, 500 MW	

R~3.2 m	PilotST	pth! E ~ R 2.7 B 5.5

Bmax~23T	

B0 ~ 9.2 T	

Whyte, NAS, 12/17	

Bmax~19 T	

B0 ~ 6 T	

B. Sorbom et al
FED 2015	

Menard et al Nucl. Fusion 56 2017	

20	

Many news technologies, developed outside fusion,
should be leveraged to improve our fusion science andenergy product. And these are often highly synergistic	

Innova&on

Descrip&on

Bo/om	  line	  impact

3D	  prin(ng	  (1)Components	  with	  internal	  eﬃcient	  cooling,	  precise	  alignment

Uprated	  heat	  removal	  limits,	  simpliﬁed	  assembly

Liquid	  blankets	  (2)Liquid	  Tri(um	  breeding	  and	  heat	  extrac(on	  in	  tanks

Simpler	  build,	  higher	  reliability	  and	  availability,	  leverage	  ﬁssion

Demountable	  jointed	   Ability	  to	  take	  the	  machine	  apart	  to	  magnets	  (3)service	  internals

Higher	  availability,	  mul(-­‐mission	  plants

Machine	  learning

Predic(ons	  of	  plasma	  performance	  and	   Op(mized	  performance,	  avoid	  stability
damaging	  disrup(onsEnhanced	  conﬁnement	  modes

BeSer	  plasmas	  than	  H-­‐mode	  in	  the	  same	  device,	  e.g.	  I-­‐mode

Supercomputer	  simula(onsPredic(ve	  understanding	  of	  plasmas	  for	   Plasma	  op(miza(on	  for	  higher	  op(miza(on	  of	  core	  (c.f.	  Bonoli	  et	  al)performance

Whyte, NAS, 12/17	

Higher	  plasma	  performance	  overall,	  smaller	  devices

21	

Many news technologies, developed outside fusion,
should be leveraged to improve our fusion science andenergy product. And these are often highly synergistic	

7	

Innova&on

Descrip&on

Bo/om	  line	  impact

Inside	  launch	  antennas	  (4)Advanced	  antennas	  for	  current	  drive	  and	  hea(ngLower	  recircula(ng	  power,	  longer	  life	  internals

Long-­‐leg	  divertors	  (5)New	  magne(c	  geometries	  for	  beSer	  plasma	  heat	  exhaust

Uprated	  performance	  and	  longer	  life,	  higher	  power	  density

Higher	  temp	  cryogens Higher	  opera(ng	  temperatures	  and	  more	  eﬃcient	  cooling
Nuclear	  shielding	  materials	  (6)Op(mized	  to	  reduce	  required	  thickness	   Smaller	  devices	  or	  longer	  life(mesin	  key	  areas

HTS	  superconductors	   Access	  higher	  ﬁeld,	  operated	  at	  higher	  (7)	  temperatures,	  larger	  SC	  margin	  Whyte, NAS, 12/17	

Lower	  recircula(ng	  power,	  smaller	  devices

Smaller	  devices	  for	  plasma	  and	  fusion	  science	  22	Other US-centric innovations 
we are not pursuing in earnest	

- Quasi-axisymmetric stellarators  recovering tokamak
confinement 	

- Modular SC coil design for stellarators	

- jointed coils?	

- PPPL-design of “straight coils” for outer section	

- Liquid plasma-facing surfaces (c.f. Boundary Workshop)	- GDT neutron source	Whyte, NAS, 12/17	

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The virtuous circle of the high-field compact “road” leads to increased US strategic opportunities 	Configuration optimization
Stellarators, ST, Advanced divertors,	

3D printing, liquid blankets, etc.	

US-based	

economic 	

target for fusion	

Whyte, NAS, 12/17	

Multiple paths
to burning	

plasma	

Impact/connections	outside fusion	(NMR, HEP, etc.)	

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My recommendations	• Leadership in developing fusion energy as a commerciallycompetetive energy source is in our national interest	•And this is unlikely if we stay on our present path, only lock-stepped
to a much larger, risk-adverse international effort	• There must be an innovation-driven, fast-moving US fusion
program regardless of the ITER decision	•••••
Whyte, NAS, 12/17	

And we have the talent, resources and overall US creativity/
innovation to carry this out.	

We must act soon with several modest, but “needle-moving”
initiatives	

Re-establish our credibility to deliver exciting science	

Inject enthuasiasm across full spectrum of our community	

And with sponsors	

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“I shall be telling this with a sigh, Somewhere ages and ages hence:
Two road diverged in a wood, and I ---I took the one less traveled by, and that has made all the difference”	

Whyte, NAS, 12/17	

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YT	

Plasma Science & Fusion Center

Thank you

Whyte, NAS, 12/17	

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