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DT polarization and Fusion Process Magnetic Confinement Inertial Confinement

DT Polarization for ICF. DT polarization and Fusion Process Magnetic Confinement Inertial Confinement Persistence of the Polarization - Polarized D and 3 He in a Tokamak - DD Fusion induced by Laser on polarized HD The “Few-Body” Problems Static Polarization of HD

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DT polarization and Fusion Process Magnetic Confinement Inertial Confinement

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  1. DT Polarization for ICF • 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 J.- P. Didelez

  2. 95% – 99% S = ½ S = 1 S = 3/2 S = ½ D + T → 5He (3/2+) → 4He + 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 and αhave preferential directions Sin2(θ) • n from DD fusion are suppressed QSF (Jülich – Gatchina) DT polarization and Fusion Process (Kulsrud, 1982) (More, 1983) D + T → 4He (3.5 Mev) + n (14.1 MeV) + 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 J. MEYER-TER-VEHN, Nucl. Phys. News, Vol 2 N° 3 (1992) 15

  5. 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 A:unpolarized DT B:polarized DT

  6. DD D2T2 ? DT D2 T2

  7. 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

  8. 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

  9. 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 , FB Bonn (2009)

  10. POLAF proposal (RCNP, ILE and ORSAY) with themulti-detector “MANDALA” at ILE - Osaka . ΔE ΔE f10 cm Count Count BC-408 scintillator t10 cm PMT ×422 ch DD neutron energy [MeV] DD neutron energy [MeV] Target Chamber Target Chamber 13.42 m 13.42 m D～2.2m D～2.2m neutron detector neutron detector MANDALA MANDALA 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.

  11. Static Polarization of HD B/T > 1500 Dilution Refrigerator 10 mK and 17 T (B/T = 1700)

  12. Static Polarization of HD :DR 10 mK, 17 T solenoid 1K Pot 1220mm 538mm Mixing Chamber Null Coil 170mm 70mm Correction Coil 550mm Main Coil NbTi joints & Switch Nb3Sn joints & Protection Circuit 600mm Rough dimensions of the magnet 400mm

  13. Dynamic Polarization of HD or DT ~50% Transitions made possible through microwave excitation: ~70GHz ~50% Adding free electrons. For B=2.5 T and T = 1 K, e- polarization = 92% B ~50% 92% Solem et al. in 1974 reach 4% H polarization with HD containing 4 - 5 % H2 D2 e- ~50% e- Proton or Triton Initial concentration Needed o-H2: < 0.02 % p-D2: < 0.1% Protonrelaxation time >> electron

  14. Extraction Valves Mass Spectrometer Distillator Sampler Tanks

  15. Conclusions Polarization looks like 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 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.

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

  17. TNSA on « thick » Targets

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

  19. 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

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

  21. 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??)

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

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