DT polarization and Fusion Process

Magnetic Confinement Inertial Confinement

Persistence of the Polarization - Polarized D and 3He in a Tokamak - DD Fusion induced by Laser on polarized HD

The “Few-Body” Problems

Static Polarization of HD Dynamic Polarization of HD and DT

POLAF Project at ILE (Osaka)

Conclusion

DT Polarization for ICF

DT polarization and Fusion Process

(Kulsrud, 1982)(More, 1983)D + T → 4He (3.5 Mev) + n (14.1 MeV) + 17.6 MeV

S = ½S = 1

S = 3/2S = ½

95% – 99%D + T → 5He (3/2+) → 4He + n

1% – 4%

S = 3/23/2

1/2

-1/2

-3/2

S = 1/21/2

-1/2

4 states

2 states

2/3 of the interactions contribute to the reaction rate

If D and T are polarized then - all interactions contribute

- n and α have preferential directions Sin2(θ)- n from DD fusion are suppressed QSF (Jülich – Gatchina)

50 % Increasein released energy

The question is to know if the polarization will persist in a fusion process ?Depolarization mechanisms are small:

1) Inhomogeneous static magnetic fields, 2) Binary collisions,3) Magnetic fluctuations , 4) Atomic effects

(3.37 1011 J/g)

Plasma Density n = 1014 (cm-3) ; Confinement Time τ = 10 (sec) Lawson Criterion (n τ > 1015 (sec/cm3)

Fusion by Magnetic Confinement – (ITER)

ITER

Plasma Volume = 873 m3

τ = 300 (sec)

Power = 500 MW

Fusion by Inertial Confinement – (MEGAJOULE)

Plasma Density n = 1026 (cm-3) ; Confinement Time τ = 10-10 (sec) Lawson Criterion (n τ > 1015 (sec/cm3)

ICF

Target 3mm radiusCarbone &

4 mg cryogenic DT

2000 times compressed300 g/cm3

5 keV

825 MJ within 100 ps

J. MEYER-TER-VEHN, Nucl. Phys. News, Vol 2 N° 3 (1992) 15

A:unpolarized DT

B:polarized DT

At fixed G: EB / EA < 0.7

for G=100 EA = 880 kJ EB = 510 kJ

EAmin = 450 kJ

EBmin = 290 kJ

for E = 1 MJ GA = 140

GB = 307

DDD2T2

DTD2 T2

?

Fusion by Magnetic Confinement – (ITER)

Persistence of the Polarization

- Injection of Polarized D and 3He in a Tokamak (A. Honig and A. Sandorfi)

D + 3He → 4He + p + 18.35 MeV

(DIII-D Tokamak of San Diego, USA)

Expected: 15% increase in the fusion rate

- Powerful Laser on a polarized HD target → P and D Plasma

P + D → 3He + γ + 5.5 MeV

Expected: Angular distribution of the γ ray Change in the cross section

D + D → 3He + n + 3.267 MeV

Expected: Change in the total cross section Sin2θ angular distribution of the neutrons

Powerful Laser (Terawatt)creates a local plasmaof p and d ions (5 KeV)

5.5 MeV γ ray fromp + d → 3He + γ

2.45 MeV n fromd + d → 3He + n

Tentative Set-Up

Polarized HD Target25 cm3

H (p) polarization > 60%D (d) vect. polar. > 14%

200 mJ, 160 fs 4.5 µm FWHM

970 nm, ~ 1018 W/cm2

The “Few-Body” Problem

d

1/2 1

p d

3He

γ

dσ4/dωγ ~ (1+ cos2 θ) * (S = 3/2)

σ0 (10 keV) = 18 µbarn **1 - 10 radiative captures/laser shot ?

For polarized plasma, angular dependence relative to the polarization axis, but forward peaked, small cross section and almost impossible to detect the γ (EM background).

dσ5/dωn ~ sin2 θ *** (S = 2)

σ n5 / σ0 < 0.5 ; σ0 (1.5 MeV) = 100 mbarn ***

For polarized plasma, angular dependence perpendicular to the polarization axis, large cross section and “easy” detection of the very slow neutrons. Possibility to rotate the polarization of the RCNP HD target without any other change. High “D” polarization possible by AFP.

* M. Viviani ** G. J. Schmid PR C52, R1732 (1995) *** A. Deltuva , FB Bonn (2009)

HD Plasma5 keV

3He

d d

n

POLAF proposal (RCNP, ILE and ORSAY) with themulti-detector “MANDALA” at ILE - Osaka .

An energy resolution of 28 keV for 2.45-MeV DD neutrons is achieved with MANDALA.

An energy resolution of 28 keV for 2.45-MeV DD neutrons is achieved with MANDALA.

13.42 m 13.42 m

Target Chamber

Target Chamber

MANDALAMANDALADD neutron energy [MeV]

Co

un

t ΔE

2

5.82

)()(

keV

keVE

Ti

D ～ 2.2 m

neutron detectorneutron detector

t10 cm PMT

10 cm

BC-408 scintillat

or×422 ch

An energy resolution of 28 keV for 2.45-MeV DD neutrons is achieved with MANDALA.

An energy resolution of 28 keV for 2.45-MeV DD neutrons is achieved with MANDALA.

13.42 m 13.42 m

Target Chamber

Target Chamber

MANDALAMANDALADD neutron energy [MeV]

Co

un

t ΔE

2

5.82

)()(

keV

keVE

Ti

D ～ 2.2 m

neutron detectorneutron detector

Static Polarization of HD

B/T > 1500

Dilution Refrigerator 10 mK and 17 T (B/T = 1700)

1220

mm

170mm

70m

m

Mixing Chamber

Nb3Sn joints&Protection Circuit

NbTi joints&Switch

Main CoilCorrection Coil

Null Coil

Rough dimensions of the magnet

400mm

600m

m

550m

m

1K Pot

538m

m

16.990

16.992

16.994

16.996

16.998

17.000

17.002

17.004

17.006

17.008

17.010

- 100 - 80 - 60 - 40 - 20 0 20 40 60 80 100

0

5

10

15

z (mm)

B (T)R(mm)

150mm

500ppm

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

400 500 600 700 800 900 1000 1100 1200

0

10

20

30

40

50

60

70

80

z (mm)

B (T)R(mm)

Static Polarization of HD : DR 10 mK, 17 T solenoid

B

Adding free electrons. For B=2.5 T and T = 1 K, e- polarization = 92%

Proton relaxation time >> electron

92%

~50%

~50%

Initial concentration Needed

o-H2: < 0.02 %p-D2: < 0.1%

e-

e- Proton or Triton

Dynamic Polarization of HD or DT

Solem et al. in 1974 reach 4% H polarizationwith HD containing 4 - 5 % H2 D2

Transitions made possiblethrough microwave excitation: ~70GHz

~50%

~50%

Mass Spectrometer

Sampler Tanks

Distillator

Extraction Valves

Conclusions

Polarization looks like a MUST for future power plants.We have in Europe (and in France): ITER to study the magnetic confinementand MEGAJOULE for the inertial confinement.

The full polarization of DT fuel increases the reactivity by at least 50% and controls the reaction products direction of emission. Simulations of ICF 100%.The cost of a polarization station (107 €) is negligible compared to the cost of a reactor (1010 € for ITER).

A first question remain: D and T relaxation times during fusion process ? We have proposed a “simple” experiment to approach this question, at least for the inertial confinement: POLAF Project accepted at ILE (OSAKA) Feasibility of the experiment confirmed for D + D → 3He + n reaction which can also test the RPA features

Polarization of the fuel?DNP of HD and DT must be revisited seriously somewhere,as well as high intensity polarized D2 and T2 molecular jets.

J.-P. Didelez and C. Deutsch, « Persistence of the Polarization in a Fusion Process », LPB 29 (2011) 169

TNSA on « thick » Targets

HD Target: NMR Measurements0.85 T – 1.8 K

Back conversion at room temp.for 5 hours is 30%

HD Target: Production

Step I: HD purity monitoring – Quadrupole Mass Spectrometer

HD quality on the market ?

Step II: HD production – Distillation apparatus in Orsay

Over 3 month of ageing necessary

Distillation apparatus in Orsay

3 extraction point3 temperature probe

To mass spectrometer

Stainless Steel column filled with Stedman Packing:

Heater 1

Heater 2

- Demontrate the persistence with an ultrashort laser and a polarized HD target (HIIF2010, GSI Darmstadt, August 2010)

- Develop the Dynamic Nuclear Polarization of HD (SPIN2010, KFA Jülich, September 2010)

- DNP of DT molecules (HIIF2012, ? )

- Fusion of polarized DT at Mégajoule (20??)