Fusion neutron source as a developmental step to commercial fusion energy

ICPP 2016Kaohsiung, Taiwan

Jay Anderson, Cary Forest, Oliver Schmitz, John Sarff, Paul Wilson

UW-Madison

IAEA Fusion Enterprise MeetingSanta Fe NM 2018

Outline

2

• Volumetric neutron source is needed - complements, does not replace, point source

• The Gas Dynamic Trap configuration is ready - game changing scientific and technological developments - GDT/ tandem mirror reactor path

3

A next-step gas dynamic trap is a good strategic move for the US

Fusion

Energy to the grid (attractive path evolving)

Neutron source for fusion materials development and industrial applications

Enabling technologiese.g. HTS, NBI, steady state operations,

tritium handling: common to most magnetic confinement schemes

4

There is a growing community consensus that a low cost and

accelerated VNS for materials and component testing must be considered;

only alternative may be component testing on pilot plant

Slides taken from recent presentations to NAS Panel

5

SHINE: Fusion-Fission Hybrid for Mo99 production using D beam into T gas target

A fusion neutron source has many current and future applications

6

Fusion neutron source in industry is stepping stone to energy production

• Phoenix Nuclear Labs/ SHINE planned path for commercialization of fusion via neutron source development

• Step 1: non destructive testing, demining $ - $$ • Step 2: large scale medical isotope production - moly 99 $$$$ • Step 3: transmutation of large quantities e.g. transuranic waste mitigation; large

scale production of valuable isotopes - Recall Gordon’s talk: Hanford cleanup expected to cost additional $114B

• Step 4: fusion power

7

deuterium ion beam

high pressure tritiumtargetLow-enriched

uranium blanket

• Tritium handling fusion facility licensed by the NRC - moved at ”speed of light”

• Tc99 (from moly 99) is usedin 50,000- 70,000 medical imaging procedures (~$5M)per day

• Production facility under construction in Janesville, WI; commercial production starts 2019

14 MeV fusion neutrons

The SHINE Fusion Fission Hybrid uses very simple technology to breed Mo99

Outline

8

• Volumetric neutron source is needed - complements, does not replace, point source

• Is the Gas Dynamic Trap configuration ready ?- game changing scientific and technological developments - GDT/ tandem mirror reactor path

Gas dynamic trap experiment, Novosibirsk

9

10

1

B z(T

)

Gas dynamic trap experiment, Novosibirsk

10A.A. Ivanov, Fusion Science & Technology 55 2010 Idea: V.V. Mirnov and D.D. Ryutov JETP 1979

Gas dynamic trap experiment, Novosibirsk

11

Localized neutron flux ideal for test facility; short pulse experiment free of microinstabilites

12A. Anikeev

13

Remarkable physics and technological developments justify another look in the mirror

• Perceived physics flaws - min B stabilization- low Te, electron confinement- microinstabilities

• Technology gaps to a reactor- ~MeV neutral beams- >~100 GHz gyrotrons- requires superconducting coils

1986: US cuts mirror budget ~95%

14

Remarkable physics and technological developments justify another look in the mirror

• Perceived physics flaws - min B stabilization- low Te, electron confinement- microinstabilities

• Technology gaps to a reactor- ~MeV neutral beams- >~100 GHz gyrotrons- requires superconducting coils

1986: US cuts mirror budget ~95%:

• Remarkable physics achievements- axisymmetric high b equilibrium

* DCLC, AIC stabilized - Axial electron confinement solved

* successful ECH -> Te ~ 1keV

Today:

15

Remarkable physics and technological developments justify another look in the mirror

• Perceived physics flaws - min B stabilization- low Te, electron confinement- microinstabilities

• Technology gaps to a reactor- ~MeV neutral beams- >~100 GHz gyrotrons- requires superconducting coils

1986: US cuts mirror budget ~95%:

• Remarkable physics achievements- axisymmetric high b equilibrium

* DCLC, AIC stabilized - Axial electron confinement solved

* successful ECH -> Te ~ 1keV

Today:

16

A Neutron Source Design

A.A. Ivanov and V. V. Prikhodko, PPCF 55 2013 and references therein. A.A. Ivanov, Fusion Science & Technology 55 2010

• PNBI ~50 MW @ 65 keV DT steady-state• Bc = 1.3 T, Rmirror = 10 (based on low Tc)• L = 15 m• 15 dpa/ full power year • 150g Tritium consumption/ full power yearWith Te = 0.65 keV• Neutron Flux = 2 MW/m2 (4x ITER flux)

GDT Device at Novosibirsk

PNBI ~ 5 MW @ 25 keV for 5 msBc = 0.3 TRmirror = 17L = 7 mTe ~ 0.9 keV

ConjectureScales to neutron source

Outline

17

• Volumetric neutron source is needed - complements, does not replace, point source

• Is the Gas Dynamic Trap configuration really ready to go to neutron source ??- game changing scientific and technological developments - GDT/ tandem mirror reactor path

Neutron source development effort at UW-Madison

18

• Small seed grant from University ($500k, 2 years) to formulate plans

• Neutron source design underway- magnetic field profile,- auxiliary heating recipe for optimized fusion neutron flux, spatial localization

• An intermediate step is prudent for risk retirement

• A small prototype of the prototype is under construction - leveraging several $M in stored equipment;

10MW D NBI + 4MW HHFW @ 30MHz

-6 -4 -2 0 2 4 6Z (m)

1000

0

2000

3000

n flu

x (W

/cm

2/sr

) Using well-verified tokamak code, CQL3D; will also try to match

published Novosibirsk GDT data

Next steps toward establishing the GDT as a credible candidate for a volumetric neutron source

19

• GDT opportunity: Fusion neutron production via beam-into-plasma reactionsRequired parameters: density ~1020 m-3, Te~1 keV, 80 keV neutral beam energySystem scoping studies predict 1015 D-D neutron/s for these parameters

• Axisymmetric MHD stability: b~60% • Sufficient electron thermal confinement with Te ~ 0.9 keV• Beam-driven micro instabilities not yet observed (25 kV beams, 5 ms)• Self-plugging by sloshing ions• ExB stabilization from biased limiters

Next steps toward establishing the GDT as a credible candidate for a volumetric neutron source

20

• GDT opportunity: Fusion neutron production via beam-into-plasma reactionsRequired parameters: density ~1020 m-3, Te~1 keV, 80 keV neutral beam energySystem scoping studies predict 1015 D-D neutron/s for these parameters

• Status of plasma physics: Stable, short-pulse plasmas at requisite parametersKey science advances from the GDT program at Novosibirsk GDT, Novosibirsk

• Axisymmetric MHD stability: b~60% • Sufficient electron thermal confinement with Te ~ 0.9 keV• Beam-driven micro instabilities not yet observed (25 kV beams, 5 ms)• Self-plugging by sloshing ions• ExB stabilization from biased limiters

Next steps toward establishing the GDT as a credible candidate for a volumetric neutron source

21

• GDT opportunity: Fusion neutron production via beam-into-plasma reactionsRequired parameters: density ~1020 m-3, Te~1 keV, 80 keV neutral beam energySystem scoping studies predict 1015 D-D neutron/s for these parameters

• Status of plasma physics: Stable, short-pulse plasmas at requisite parametersKey science advances from the GDT program at Novosibirsk

• Next step: A mid-scale, non-nuclear experiment can resolve outstanding physics questions and exploit game-changing technology• Establish high density plasma target formation (fueling, pumping)• Identify MHD stability limits (outflow and rotation; shaping in expander region)• Identify kinetic stability limits with a stationary fast ion distribution (tNBI >> tslowing-down)• Understand and control electron confinement, e.g., heat conductivity through double

layers, secondary emission from target, ECH or Helicon rf heating• Exploit REBCO magnets to increase plasma density and fast ion confinement• High energy neutral beams (80 keV) + HHFW for fast ion distribution control

GDT, Novosibirsk

Where does a next step mirror fit; how do we get there?

22

Where does a next step mirror fit; how do we get there?

23

Z (m)r (

m)

Investment of internal funding by UW-Madison is being used to construct a GDT prototype device featuring HTS magnets

• The Rotating Wall Machine is being repurposed as a prototype mirror device– The UW has invested $550k (equivalent to ~$800k DoE dollars)– Will produce high density helicon target plasma – 0.7 MW, 20 kV NBI for short pulse fast ion studies– Expander physics with Li end walls – Rotation/ biasing with LaB6 cathodes

24

Prototype assembly underway.

Investment of internal funding by UW-Madison is being used to construct a GDT prototype device featuring HTS magnets

• The Rotating Wall Machine is being repurposed as a prototype mirror device– The UW has invested $550k (equivalent to ~$800k DoE dollars)– Will produce high density helicon target plasma – 0.7 MW, 20 kV NBI for short pulse fast ion studies– Expander physics with Li end walls – Rotation/ biasing with LaB6 cathodes

25-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5Z (m)

0246

Bz (T

)

-1.0

-0.5

0.0

0.5

1.0

Z (m

)

-1.0

-0.5

0.0

0.5

1.0

-1.0

-0.5

0.0

0.5

1.0

Prototype device in UW Physics Dept. GDT type magnetic field (Rm>15)

• 6 T REBCO coil under construction(collaboration with GA)– Will help drive use of HTS for plasma

confinement

Investment of internal funding by UW-Madison is being used to construct a GDT prototype device featuring HTS magnets

• The Rotating Wall Machine is being repurposed as a prototype mirror device– The UW has invested $550k (equivalent to ~$800k DoE dollars)– Will produce high density helicon target plasma – 0.7 MW, 20 kV NBI for short pulse fast ion studies– Expander physics with Li end walls – Rotation/ biasing with LaB6 cathodes

26

Proto-type device in UW Physics Dept. GDT type magnetic field (Rm>15)

Limited field line

Cryostat

Water-cooled aperture

Investment of internal funding by UW-Madison is being used to construct a GDT prototype device featuring HTS magnets

27

Proto-type device in UW Physics Dept.

Physics goals for proto-type experiment:• Demonstrate MHD stability in GDT geometry at moderate plasma regime (ne~2.0 1019 m-3, Te~100eV)• Understand and control Te• Explore use of liquid Li in end-cells; compatibility with GDT plasma fueling and exhaust

First plasma 5/30/18, central solenoid only

Off-the-shelf MRI coils3T 1T Plasma generating

rf antennas

Electron heatingsystem

High field REBCO magnet

Plasma absorber, stability and rotation control

Neutral beam sourceof energetic ions

A cost-effective magnet upgrade would establish a high-field experiment, moderate pulse (100 ms) experiment

28

Upgrade features:• Reliable, low-cost central cell magnets using commercial MRI-industry magnets (1-3T @$400k)

• Two compact, 30T high-field mirror plug coils (simple planar REBCO coils)

• Novosibirsk-developed NBI injection for fast ions• Expanding-field Li diverter for MHD stability and

pumping• HHFW for heating ions at turning points• ECH/helicon for plasma formation and Te control

a= 10 cmPNBI = several MWPECH = 1 MWfECH = 110 GHz

Path to reactor: evolving; will benefit from performance extension device.

29T.K. Fowler, R.W. Moir, and T.C. Simonen, Nuclear Fusion 57 2017

A new simpler way to obtain high fusion power gain in tandem mirrors

Utilizes ITER-scale NBI, ECH55 meter length, 24 T mirror coils, 1.2GWe

GDT route: • Recall plasma lifetime ~ Rm L (without any

confinement enhancement)• All power losses out ends; independent of L • GDT reactor quite long: ~1km. • Reactor shrinks with each confinement

improvement- sloshing ion self-plugging- electrostatic potential barrier- tandem or multi-mirror end cells- rotation/ centrifugal confinement

Path to reactor: still evolving

30

Component Basis short pulse 100 ms

steady-state DT Neutron Source(actinide burner,

neutron test facility)

Tandem Mirror Reactor

First Experiments 2020 (3yrs) 2023 (6 yrs) 2030 (10 yrs) 2035 (15 yrs)6 x 1 m long, 3TCentral Cell SC Magnets

$400k/magnet, turnkey from Phillips

$2.5M

2 x 30T, 10 cm bore field REBCO coils

jointly develop with high field magnet lab (Florida or MIT) $5M

Vacuum Vessel $2MPumping System $1M +$4M

2 110 GHz, 1MW gyrotrons (CW)

$4/watt GA / steady state

$2M (GA tubes??)

+$6M

4 MW HHFW (50-60 MHz, CW)

$2/watt $2M +$6 M +$20M (+10 MW)

4 MW 80 kV, deuterium neutral beams, 100 ms

$2/watt $8M +$10 M +$20M (+10 MW)

Diagnostic Set Move Thomson, MSE and ChERS spectroscopy, NPA, from MST

$1M +$2M

Plugs, End Cells, Stabilizers

Contingency $6.5MSiting UW Campus in

Sterling or PSLprovided by UW

provided by UW xxx

Cumulative Investment $30M $60M $xxx M $x,xxx M

Summary:

31

• Volumetric neutron source in mirror geometry should be built

- materials testing, enabling technologies for mainstream magnetic confinement - spin-off to industry could be quite profitable;

* (another) success of fusion application could improve public perception

• Risk retirement in performance extension device required- steady state ion distribution - particle handling/ sustained electron confinement in steady state

• Attractive reactor scenario exists; could be substantially approved* costing analysis for DT operations & reactor not yet mature

32

Appendix

Input power required to sustain warm plasma; escaping plasma provides MHD stability

33

particle flux

nozzle area

energy/electron losttwo ends

GDT HF GDT NS

Te 1 keV 1 keV

a 5 cm 7 cm

ne 1019 m-3 5 x 1019 m-3

Rm 20 30

Ploss exp~5 MW ; theory=2.7 MW 18 MW

Thermonuclear Breakeven Length with GDT requires non-equilibrated electrons

•Each factor of 2 is a big improvement•sloshing ion self-plugging•rotation•tandem or multi mirror

•2.5 km, a = 20 cm is 300 MW •Ti=50 keV, Te=1 keV??

Overview of ECR plasma heating experiment in the GDT magnetic mirror, P. Bagryansky 2015

Gas Dynamic

TrapMirror-to-mirror distance 7m

Magnetic field at midplane 0.35 T (0.27 T)

Mirror ratio 35

Number of injector modules 8

Total neutral beam (NB) power 5MW

Trapped NB power 1.8MW

Time of NB operation ≈ 5ms

NB injection angle 45◦

Energy of NB particles 25 keV

Mean energy of fast ions 9 keV (12 keV)

Warm ion density at midplane 2 x 1019m−3

Fast ion density at turning points 5 x 1019m−3

Electron temperature up to 250 eV (<180 eV)

Plasma radius at midplane 0.14m

Maximum local plasma β 0.6

GDT performs better with vortex stabilization

P. Bagryansky 1990P. Bagryansky 2000

Anikeev, 1997 Ivanov 2010

(Ellis MCX 2008)

Secondary electron emission from lithium and lithium compoundsA. M. Capece, M. I. Patino, Y. Raitses, and B. E. Koel

Citation: Appl. Phys. Lett. 109, 011605 (2016); doi: 10.1063/1.4955461View online: https://doi.org/10.1063/1.4955461

Pristine Lithium has low SEE, oxidized does not

Sputtering Yield from ion bombardment is low if Li temp is low