Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Development of a High FluenceFusion Neutron Source and

Component Test FacilityBased on the Magneto-kinetic

Compression of FRCs

John Slough, David Kirtley, Chris Pihl, and George Votroubek

MSNW LLC8551 154th Avenue NERedmond WA 98052

URL: http://www.MSNWLLC.com

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Motivation for CTF based on the FRCCriteria for Component Test Facility:

(1) Provide an environment close to the fusion reactor(a) On the smallest physical scale (cost and timeliness)(b) With the simplest configuration (cost and ease of use)

(2) It should be capable of evaluating the full tritium fuel cycle.(3) It should allow for easy diverter access for evaluation of a

range of materials evaluationMagneto-kinetic Compression of FRC plasmoids

Fusion Power Density scales as β2B4

(1) The FRC has the highest <β> of all fusion plasmas (<β> ~ 0.8-0.9)(2) Compression and burn occurs in a simple linear geometry at highest

possible B consistent with pulsed solenoidal coil (Bz ~15-20 T) (3) D-T fusion neutron generation provides more realistic test for

materials and tritium breeding(4) Diverter outside blanket and remote from burn chamber

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Magneto-kinetic heating to fusion temperatures: Kinetic energy is transferred from array of axially sequenced low field coils and thermalized by self compression into high field burn chamber

PHD FRC neutron source provides• Remote burn in ideal breeding geometry• Greatly simplified PFC management• Direct, High efficiency ion heating to fusion

temperature• Small, compact source maximizes wall loading with minimum environmental impact

Component Test Facility based onPulsed High Density (PHD) FRCs

Key Physics Demonstrated:• Kinetic stability from formation thru fusion burn• Observed transport scaling sufficient for Q > 1• Magneto-kinetic heating (M ~ 3) forming

robustly stable FRC • Confinement scaling better than prediction from in situ PHD FRC τ

> τLHD ~ r2n1/2

Component Test Facility

Magnetic coilsBurn Chamber

Blanket TestChamber

Diverter Chamber

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

EXTERNALFIELD

FRC CLOSED POLOIDAL FIELD

R – null radiusrs – separatrix radiusrc – coil radiusxs – rs /rc

EquilibriumRelations:

2s

r

020 x1dr

BP2

2

1s

−=μ

=β ∫

( )2s

vacext x1

BB−

=

0

2ext

00 2BkTnPμ

== Radial Pressure Balance

Axial Pressure Balance

Flux conservation

The Field Reversed Configuration (FRC)

0.5 < ⟨β⟩

< 1

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

nτ

~ 6x10-15 rs2 n1.6

Radial Pressure balance:⇒

nτ ∝ rs

2 Be3

FRC Reactor Regime Based on Observed Confinement Scaling:

In terms of confining flux φp :

nτ ∝ φp Be2

ReactorReactor BBe (T) φφ

(mWb)(mWb)MTF 200 0.5 to 1 IPA 20 20

SS FRC 1 - 2 1000

Be2 = [2μ0 n0 kT(=10 keV)] = 4x10-21n0

(with xs = 0.6 ε

= 20 )

Regime of Interest here

τN = 3.2x10-15 ε0.5 xs0.8 rs

2.1 n0.6From LSX and earlier expts:

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Bupstream

Bdc

Bdown0

•Upper plot of flux contours taken from numerical calculations for discharge1647 during the acceleration of an FRC plasmoid

•Bottom plot illustrates phasing of the accelerator coilsEach coil in turn is switched on for one complete cycle.Phase of each coil at time of calculation is indicated by arrow

FRC Plasmoid Acceleration Method Employed in IPA

Inductive Plasmoid Accelerator (IPA):

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

(1) With IPA a series of sequentially fired axial field coils accelerating two FRCs toward one another at a relative velocity of 400-800 km/s

(2) The two FRCs collide and merge, thermalizing their directed kinetic energy resulting in ions with temperatures of several hundred eV to several keV.

(3) The FRC plasmoids are compressed radially as they mergeThe resulting FRC was stable and well confined – decaying more slowly than insitu formed FRCs. The neutron flux was significantly higher than anticipated based on theradial pressure balance temperature

The Inductive Plasma Accelerator is a Device Designed toCreate Fusion Relevant, High Energy Density FRC Plasmas

Formation-Accelerator Compressor Accelerator-FormationFormation-Accelerator Compressor Accelerator-Formation

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

FRC Parameters Measured on IPA with Magnetic Compression

Midplane HeNe Interferometer+ Excluded Flux Signal

External Magnetic probe

Excluded Flux from flux and B-dot loops + B0

Radial pressure balance Eq.+ ne and B0⎟⎟

⎠

⎞⎜⎜⎝

⎛=

μ total0

20 kTn

2B

Diagnostics Employed

Supersonic Merging Process is Observed to Form Stableand Quiescent FRC Target for Simultaneous Compression

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

0 10 20

10

8

6

4

2

0

time (µsec)

CXF4_WB 373 (375)CXF4_WB 369 (375)

Δϕ(mWb)

Merging 2 FRCsSingle FRC

Vz ~ 2.1x105 m/s

0 10 20

10

8

6

4

2

0

time (µsec)

CXF4_WB 373 (375)CXF4_WB 369 (375)

Δϕ(mWb)

Merging 2 FRCsSingle FRC

Vz ~ 2.1x105 m/s

Employing a single accelerator, the FRC transits the compression section (a and b)Simultaneous firing (c) shows mergingExcluded flux measurements indicate the FRCs do merge and decay over ~40 µs

Contour plots of Δφ

axially along compression chamber

Time [ μs]

Axi

al L

ocat

ion

[m]

Axial Excluded Flux [mWb] Shot#369 (375)

6 8 10 12 14

-0.2

-0.1

0

0.1

0.2

0

1

2

3

4

5

6

7

8

Bothc) Both

Time [ μs]

Axi

al L

ocat

ion

[m]

Axial Excluded Flux [mWb] Shot#376 (375)

6 8 10 12 14

-0.2

-0.1

0

0.1

0.2

0

0.5

1

1.5

2

Gun 2 Only

Time [ μs]

Axi

al L

ocat

ion

[m]

6 8 10 12 14

-0.2

-0.1

0

0.1

0.2

0

0.5

1

1.5

2

Time [ μs]

Axi

al L

ocat

ion

[m]

6 8 10 12 14

-0.2

-0.1

0

0.1

0.2

0

0.5

1

1.5

2

Accelerator 1Only

a)

FRC Dynamic Behavior Exhibited in Excluded Flux (Diamagnetism) from Diagnostic Array

in Merging Chamber FRC

Time [ μs]

Axi

al L

ocat

ion

[m]

Axial Excluded Flux [mWb] Shot#373 (375)

6 8 10 12 14

-0.2

-0.1

0

0.1

0.2

0

0.5

1

1.5

2

Gun 1 Only

b)

Time [ μs]

Axi

al L

ocat

ion

[m]

6 8 10 12 14

-0.2

-0.1

0

0.1

0.2

0

0.5

1

1.5

2

Accelerator 2Only

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

0.10

1.4 1.2 1.0 0.8 0.6 0.4 0.2 0

R(m)

Z (m)

0

2

4

6

8

20

time(µsec)

2D MHD Calculations Based on Measurements andResults from IPA (2008)

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Phase 0:Proof of Concept

Demonstrated 2008

Phase 1:IPA-HF

Nneut ~ 1015/pulse

Phase 2:CTF

(IPA-HF@800 Hz?)Phase 3:

Q=1.5Thorium Breeder

Large ScaleTransmutation

Of High Level Waste

Increasing Fusion Neutron Production Enables Several ApplicationsSuch as Fissile Fuel Breeding, and Waste Transmutation

6.2i

DT3/1

c

p2/3

p4/7

31neut T

vrEB

10x62.2N ⟩σ⟨ϕ=

103

104

105

1061011

1012

1013

1014

1015

1016

1017

1018

Neu

trons

per

pul

se

Ep (J)

*

*

IPA (2008)

IPA- HF (2010)

CTF (2012)

B = 2 T5 T

10 T15 T

rc = 0.1 mϕp = 10 mWb (40)Ti = 8 keV

* D-T fuel assumed

*

Development Plan for FRC Based CTF

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

MHD Calculation for Next Step Experiment: IPA-HF

Z (m)

0

2

4

6

8

120.2

0

1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0

R(m) time

(µsec)

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Vz

(km/s)

Average Te Average Ti

IPA66-1-18

6

4

2

0

T(keV)

IPA66-1-1

0 2 4 6 8 10 12T (µsec)

600

400

200

0

-200

• IPA-HF increases plasmoid KE and TE prior to compression• Optimum yield Ti attained quickly maximizing neutron yield

Supersonic collisionalmerging heats only ions

Compressional heating adiabatically heats bothions and electrons

Ions remain much hotter thanElectrons for FRC lifetime

in IPA-HF

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Compression Experiment: IPA-HF

•IPA-HFC will provide verification of scaling at compression fields up to 10 T•This requires a capacitor bank upgrade (~1/2 MJ)•FRC plasmoid parameters at or near those desired for CTF

Current IPAExperiment

IPA-HF

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

For a given energy input to the plasma, The optimum neutron yield is at a somewhat lower temperature than Lawson for FRC scaling

Temperature Dependence of Neutron Production

2 4 6 8 10 12 14 16 18 200

1

2

3

x 10-22

0

0.5

1

1.5

2

x 10-25

D-T

cro

ss-s

ectio

n <σ

v>(m

3s-1

)

Ti (keV)

<σv>D-TTi

2.6

<σv>D-T<σv>D-TTi

2.6

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Employment of D-T Fusion Neutron Source is Optimum for Both Materials Damage Studies as well as Tritium

Processes In Blanket and Diverter

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Flexible Blanket for Breeding Studies Blanket coverage should beclose to 100%;

- Point-like neutron source - Long cylinder with only smallon-axis ports for diverter.

- No beam, antenna, or pumping ports

No significant structural elements between blanket and plasma:

- PFC - structural Be (10 cm)- End supported, rigid cylinders- Simple, flow through geometry

Helium gasCoolant(solid)

Axial magnetic field

Burning Plasma

Flux break(for pulsed)

Magnet(pulsed or SC)

Breeding Blanket(Liquid, Molten salt,

Or Solid)

2 m

Berylliumcylinder

(first wall)

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Phase 0:Proof of Concept

Demonstrated 2008

Phase 1:IPA-HF

Nneut ~ 1015/pulse

Phase 2:CTF

(IPA-HF@800 Hz?)Phase 3:

Q=1.5Thorium Breeder

Large ScaleTransmutation

Of High Level Waste

Increasing Fusion Neutron Production Enables Several ApplicationsSuch as Fissile Fuel Breeding, and Waste Transmutation

6.2i

DT3/1

c

p2/3

p4/7

31neut T

vrEB

10x62.2N ⟩σ⟨ϕ=

103

104

105

1061011

1012

1013

1014

1015

1016

1017

1018

Neu

trons

per

pul

se

Ep (J)

*

*

IPA (2008)

IPA- HF (2010)

CTF (2012)

B = 2 T5 T

10 T15 T

rc = 0.1 mϕp = 10 mWb (40)Ti = 8 keV

* D-T fuel assumed

*

Development Plan for FRC Based CTF

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Method for producing suitable fusion plasma demonstrated:

IPA Experiment (2008)

Component Test Facility (2012)

Magnetic coilsBurn Chamber

Blanket TestChamber

Diverter Chamber

IPA-HF (2010)

Optimum Fusion Ti reached with Nneut ~ 5x1014 /pulse

Rep Rated IPA at sufficient fluence for Pneut (wall) > 1 MW/m2

Timeline and Cost for FRC Based CTF

~ $600k

~ $2.5 M

~ $30 M

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

Compression section

Drift section(future accelerator)

Dynamic formationsection

UW Plasma Dynamics Laboratory

FRC device at scale desired formation section for CTF has beenAchieved on the PHD device at the University of Washington

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

( )1Q)M1(Q

1EE

thinblththDT

elec −ηη++ηη

=

•Fusion electrical energy generation per fusion increases little beyond Qfus ~ 5 with high ion heating efficiency

•Blanket heating from fissile fuel production dominates electrical energyproduction for Qfus > 1

•Even for Q < 1 additional energy generation from bred fissile fuel dwarfs energy production from Q = ∞

fusion alone

EDT - energy from fusion reaction= 17.6 MeV ×

NDTηth - therm. to elect. conv. eff. = 0.4ηin - ion heating efficiency = 0.7Mbl – effective blanket multiplication

= 0.14 [6Li ⇒ 1.1 T + 4.8 MeV] = 2.0 [6Li,232Th ⇒ 1.1 T, 1.3 233U +

49 MeV)= 5.0 [233U,n ⇒ FP, 2.5 n+198 MeV]

Low Q More Than Sufficient for Fissile/Fusile Breeder Reactor

Qfus

DT

elec

EE

0 1 2 3 4 5-1

0

1

2

3

4

5

6

6Li blanket (Lithium fission only)6Li + 232Th blanket

(fission suppressed)6Li + 232Th blanket

(233U fuel burnedin fission reactor)

Qfus = ∞

Theme 4 ReNeW, UCLA March 2-4 2009 J. Slough

SummaryThe pulsed FRC based CTF:(1) Reduces by orders of magnitude the scale and complexity

involved in a CTF based on a spallation source, ST or tokamak(2) Provides for a vastly lower cost, risk and a much shorter

timescale for implementation(3) Can address both material exposure issues in blanket as well as

diverters.(4) Can address crucial Tritium fueling concerns –(I) Inventory, (II) Production, (III) Processing, and (IV) Recovery

All are without resolutionAll represent potential show-stoppers for DT fusion.

(5) Can be further developed to contribute to energy production in the near term (I) fissile/fusile breeder (II) Waste transmutation/burner