IPN Orsay

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

2. 95% – 99% S = ½ S = 1 S = 3/2 S = ½ D + T → He5 (3/2+) → He4 + n 1% – 4% 3/2 1/2 S = 3/2 4 states -1/2 2/3 of the interactions contribute to the reaction rate -3/2 1/2 2 states S = 1/2 -1/2 50 % Increase in released energy If D and T are polarized then - all interactions contribute - n have preferential directions Sin2(θ) DT polarization and Fusion Process (Kulsrud, 1982) D + T → 4He + n + 17.6 MeV (3.37 1011 J/g) The question is to know if the polarization will persist in a fusion process ?

3. Fusion by Magnetic Confinement – (ITER) Plasma Density n = 1014 (cm-3) ; Confinement Time τ = 10 (sec) Lawson Criterion (n τ > 1015 (sec/cm3) ITER Plasma Volume = 873 m3 τ = 300 (sec) Power = 500 MW (input 50 MW)

4. 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 radius Carbone & 4 mg cryogenic DT 2000 times compressed 300 g/cm3 5 keV 825 MJ within 100 ps

5. Persistence of the Polarization Fusion by Magnetic Confinement – (ITER) - 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

6. Tentative Set-Up Polarized HD Target 25 cm3 H (p) polarization > 60% D (d) vect. polar. > 14% 5.5 MeV γ ray from p + d → 3He + γ 2.45 MeV n from d + d → 3He + n Powerful Laser (Petawatt) creates a local plasma of p and d ions (5 KeV) 20 mJ, 160 fs, 4.5 µm FWHM, 2.1018 W/cm3

7. The “Few-Body” Problem 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 »? σn++ /σ0 = 0.08 ? Questions for the Few-Body specialists: - Is it really true ? (10 Yes: Part. W. A. & DWBA;2 No: Reson. Group. Theor.) γ d d p 1 3He 1/2 HD Plasma 5 keV n 3He d d * Eduard KURAEV (BFKL, Dubna), ** G. J. Schmid PR C52, R1732 (1995)

8. Conclusions Fusion is a MUST for future power plants. We have in Europe (and in France): ITER to study the magnetic confinement and 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.

10. HD Target: NMR Measurements 0.85 T – 1.8 K Back conversion at room temp. for 5 hours is 30%

11. Step I: HD purity monitoring – Quadrupole Mass Spectrometer HD quality on the market ? Step II: HD production – Distillation apparatus in Orsay HD Target: Production Over 3 month of ageing necessary

12. Distillation apparatus in Orsay Heater 1 To mass spectrometer 3 extraction point 3 temperature probe Stainless Steel column filled with Stedman Packing: Heater 2

13. Extraction Valves Distillator Mass Sectrometer Sample Tanks