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« Polarization and Fusion » SPIN 2010 (FZ Jülich, September 27 – October 2, 2010 )

« Polarization and Fusion » SPIN 2010 (FZ Jülich, September 27 – October 2, 2010 ). 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

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« Polarization and Fusion » SPIN 2010 (FZ Jülich, September 27 – October 2, 2010 )

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  1. « Polarization and Fusion » SPIN 2010 (FZ Jülich, September 27 – October 2, 2010 ) 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 - 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) • n from DD fusion are suppressed (previous talk by Kirill GRIGORYEV ) 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 ? Depolarization mechanisms are small: 1) Inhomogeneous static magnetic fields, 2) Binary collisions, 3) Magnetic fluctuations , 4) Atomic effects

  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

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

  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 (Terawatt) creates a local plasma of p and d ions (5 KeV) 200 mJ, 160 fs 4.5 µm FWHM 970 nm, ~ 1018 W/cm2

  7. The “Few-Body” Problem 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) σn5 /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 possibleby AFP. γ d d p 3He 1 1/2 HD Plasma 5 keV 3He n d d *M. Viviani ** G. J. Schmid PR C52, R1732 (1995) *** A. Deltuva

  8. Persistence of the Polarization in a Fusion Process What to do ? • 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??)

  9. 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 ? We propose “simple” experiments (using existing equipments) to try to answer this fundamental question, at least for the inertial confinement. Feasibility of the experiment confirmed for outgoing neutrons: - significant fusion rate observed at Garching - predictions for angular distributions of the neutrons - QSF small in DD Polarized Fusion (Kirill’s talk).

  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

  14. Mais que diable font les chercheurs émérites dans ce laboratoire ?

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