IPN Orsay FEW-BODY 19th – Bonn Jean-Pierre DIDELEZ Persistence of the Polarization in a Fusion Process J. P. Didelez IPN and C. Deutsch LPGP Orsay DT polarization.

IPN Orsay

FEW-BODY 19th – Bonn Jean-Pierre DIDELEZ

Persistence of the Polarization in a Fusion Process

J. P. Didelez IPN and C. Deutsch LPGPOrsay

DT polarization and Fusion Process

Magnetic Confinement Inertial Confinement

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

The “Few-Body” Problems

Conclusion

DT polarization and Fusion Process

(Kulsrud, 1982)

D + T → 4He + n + 17.6 MeV

S = ½S = 1

S = 3/2S = ½

95% – 99%D + T → He5 (3/2+) → He4 + 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 have preferential directions Sin2(θ)

50 % Increasein released energy

The question is to know if the polarization will persist in a fusion process ?

(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(input 50 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

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: Drastic change in the cross section

Powerful Laser (Petawatt)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%

20 mJ, 160 fs, 4.5 µm FWHM, 2.1018 W/cm3

The “Few-Body” Problem

d

1/2 1

p d

3He

γ

dσ/dωγ = σ0[(1+ cos2 θ) + b sin2 θ] *

S = 1/2 S = 3/2

σ0 (10 keV) = 18 µbarn**100 radiative captures/laser shot ?

For polarized plasma, some angular dependence relative to the polarization axis.

Questions for the Few-Body specialists:

- is the dσ/dω relation correct ? - how large is the parameter « b »?

σ n++ / σ0 = 0.08 ?

Questions for the Few-Body specialists: - Is it really true ? (10 Yes: Part. W. A. & DWBA; 2 No: Reson. Group. Theor.)

* Eduard KURAEV (BFKL, Dubna), ** G. J. Schmid PR C52, R1732 (1995)

HD Plasma5 keV

3He

d d

n

Conclusions

Fusion is 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 could increase the reactivity by 50% and control the reaction products direction of emission. The cost of a polarization station (106 €) is negligible compared to the cost of a reactor (5 109 € for ITER).

A question remains: D and T relaxation time during fusion process ?Kulsrud argued that the depolarization mechanisms are weak in the plasma.

We propose “simple” experiments (using existing equipments) to try to answer this fundamental question,at least for the inertial confinement, but reliable theoretical predictions at low energies are needed.

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

Mass Sectrometer

Sample Tanks

Distillator

Extraction Valves