Mitglied der Helmholtz-Gemeinschaft Polarized Fusion by Giuseppe Ciullo INFN and University of Ferrara for Ralf Engels JCHP / Institut für Kernphysik, FZ Jülich Nuclear Fusion with Polarized Particles

2 The first three reactor generations, organized according to relative energy (temperature) requirement for fusion. Polarized Fusion Total cross section Energy production: 1. Generation: D + T 4 He + n Highest cross section at lowest temperature 2. Generation: D + D t + p or 3 He + n Fuel everywhere available 3. Generation 3 He + D 4 He + p Neutron lean reactor if D+D suppressed (More fusion reactions are possible !) Up to now: The D + D reactions are used in scientific tokomaks (ITER is optimized for DT!)

3 Can the total cross section of the fusion reactions be increased by using polarized particles ? 3 He + d 4 He + p t + d 4 He + n J = 3/2 + / s-wave dominated (~96%) H. Paetz gen. Schieck, Eur. Phys. J. A 44, (2010) Polarized Fusion More details in A. Sandorfi’s talk and Factor: ~1.5 at 107 keV Factor: ~1.5 at 430 keV [Ch. Leemann et al., Helv. Phys. Acta 44, 141 (1971)]

4 What is the advantage for fusion reactors ? Polarized Fusion Laser Pellet target (DT pellets) (Berkeley, Orsay, Darmstadt, …) 1.) Inertial Fusion (Laser induced fusion)

5 What is the advantage for fusion reactors ? Calculation by M. Temporal et al. for the „Megajoule“ Project Polarized Fusion M. Temporal et al.; “Ignition conditions for inertial confinement fusion targets with polarized DT fuel” Nucl. Fusion 52 (2012)  DT pol =  DT unpol

6 Can the trajectories of the ejectiles be controlled by using polarized particles ? Polarized Fusion Total cross section Unpolarized differential cross section

7 1 st generation reactor: polarized fuel helps to optimize fusion reactors D + T ( 3 He + D) polarized fuel 1 st * * * D and T spin || to the confinement field:  and n emitted as sin 2  respect to B * D spin ┴ to the confinement field and T unpolarized: no influence on cross section, but the reaction products follow (1+3cos 2  ). Confirmed on mirror reaction 3 He(d,p) 4 He [Ch. Leeman et al Helv. Phys. Acta 44 (1971) 141]

8 D + D reactors D + D → T + p 50% (no n) → 3 He + n 50%(*) D + T can fuses (n) 3 He does not contribute at the ignition energy of D-D D ↑ + D ↑ spin dependent cross section (data set very poor), at low energy (electron screening ?). 2 nd D + 3 He → 4 He +p ? Can we have neutron free reactor? 3 rd If we suppress or reduce D-D fusion, we could have neutron free or lean reactors?

9 Spin allows to enhance or suppress reaction channels Neutron lean fusion reactor D - 3 He D ↑ (d ↑ p) T and D ↑ (d ↑ n) 3 He suppressed by choosing deuteron spin parallel each others S S 2 Quintet State Suppressed S S 0 Singlet state allowed D↑D↑ D↑D↑ 4 He*

10 Polarized Fusion Deltuva in Nuclear fusion with polarized nucleons Trento Nov 2013

11 Which questions must be solved ? 1.) Dependence of the total cross section from the polarization for all fusion reactions. Polarized Fusion d + d t + p 3 He + n Can cross sections be increased ? Can neutrons be suppressed ? Can the trajectories of the neutrons be controlled? Reaction is not s-wave dominated !

12 Spins of both deuterons are aligned: Only p z (q z ) and p zz (q zz ) ≠ 0 Only beam is polarized: (p i,j ≠ 0, q i,j = 0) σ(,Φ) = σ 0 () · {1 + 3/2 A y () p y + 1/2 A xz () p xz + 1/6 A xx-yy () p xx-zz + 2/3 A zz () p zz } Polarized Fusion

13 The Experimental Setup at PNPI ABS from the SAPIS project: (after upgrade) ~ 4 ∙ a/s → ~ 2 ∙ a/cm 2 POLIS (KVI, Groningen) Ion beam: I ≤ 20 μA → 1.5 ∙ d/s ( E beam ≤ 32 keV ) dd-fusion polarimeter LSP from POLIS LSP from the SAPIS project Luminosity: 3 ∙ /cm 2 s → count rate: ~ 40 /h → 2 month of beam time Detector Setup: 4π covered by - large pos. sens. Detectors - (~ 500 single PIN diodes ?) ABS from Ferrara: ~ 6 ∙ a/s → ~ 3 ∙ a/cm 2 Luminosity: 4.5 ∙ /cm 2 s → count rate: ~ 60 /h → 1 month of beam time P. Kravtsov in Nuclear fusion with polarized nucleons Trento Nov 2013

14 POLIS and Ferrara PNPI ← POLIS → ← ABS from Fe

15 Which questions must be solved ? 1.) Dependence of the total cross section from the polarization for all fusion reactions. (d+d is underway) 2.) Polarization conservation in the different plasmas ? a.) Magnetic confinement: Details in the next talk by Andrew Sandorfi (US-Patent by H. Greenside, R. Budny and D. Post on a special surface for polarization conservation on the wall !) b.) Inertial Fusion (Laser induced): - J.P. Didelez and C. Deutsch; 2011 Laser and Particle Beams M. Büscher (FZJ / Uni. Düsseldorf) „Laser Acceleration“ Polarized Fusion

16 Laser Acceleration ~ 100 GV/m Proton rich dot 20x20x0.5 μm 10 8 protons at 1.5 MeV protons up to 10 MeV Laser Acceleration of pol. 3 He 2+ ions from pol. 3 He gas jets A.Holler in Nuclear fusion with polarized nucleons Trento Nov 2013

17 Which questions must be solved ? 1.) Dependence of the total cross section from the polarization for all fusion reactions. 2.) Polarization conservation in the different plasmas ? 3.) How to produce polarized fuel ? - HD targets are available (10 mK, ~15 T -> see next talk ) -> frozen spin DT targets possible ?? Gaseous fuel a.) pol. 3 He is available („Laser-pumping“) b.) pol. T will be possible with a similar method c.) pol. D ??? Polarized Fusion

18 ANKE/COSY Main parts of a PIT: Atomic Beam Source Target gas hydrogen or deuterium H/D beam intensity (2 hyperfine states) / atoms/s Beam size at the interaction point σ = 2.85 ± 0.42 mm Polarization for hydrogen/deuterium P Z = 0.89 ± 0.01 P Z = ± 0.01 P z = ± 0.01 / ± 0.01 P zz = ± 0.03 / ± 0.01 Lamb-Shift Polarimeter Storage Cell

19 Polarized H 2 /D 2 Molecules Nuclear Polarization of Hydrogen Molecules from Recombination of Polarized Atoms T.Wise et al., Phys. Rev. Lett. 87, (2001). Measurements from NIKHEF, IUCF, HERMES show that recombined molecules retain fraction of initial nuclear polarization of atoms! polarized unpolarized P m = 0.5 Naïve model Is there a way to increase P m (surface material, T, B etc)?

20 The Setup ISTC Project # 1861 PNPI, FZJ, Uni. Cologne DFG Project: 436 RUS 113/977/0-1

21 Polarized H 2 Molecules P m = ± 0.02 n = 277 ± 31 Protons: P m = ± 0.02 n = 174 ± 19 c = ± Measurements on Fomblin Oil (Perfluorpolyether PFPE) HFS 3 (P a = ) H 2 - Ions: + T Cell = 100 K Expected max. molecular polarizaton P m = ) R. Engels et al. RSI 85 (2014)

22 Which questions must be solved ? 1.) Dependence of the total cross section from the polarization for all fusion reactions. 2.) Polarization conservation in the different plasmas ? 3.) How to produce polarized fuel ? - HD targets are available (10 mK, ~15 T -> see next talk ) -> frozen spin DT targets possible ?? Gaseous fuel a.) pol. 3 He is available („Laser-pumping“) b.) pol. T will be possible with a similar method c.) pol. D ??? => new ideas are welcome !!!! Polarized Fusion