Mitglied der Helmholtz-Gemeinschaft on the LEAP conference Polarized Fusion by Ralf Engels JCHP / Institut für Kernphysik, FZ Jülich Nuclear Fusion with Polarized Particles

2 Can the total cross section of the fusion reactions be increased by using polarized particles ? Polarized Fusion Total cross section

3 Can the trajectories of the ejectiles be controlled by use of polarized particles ? Polarized Fusion Total cross section Differential cross section

4 Can the total cross section of the fusion reactions be increased by using polarized particles ? 3 He + d 4 He + p Factor: ~1.5 at 430 keV [Ch. Leemann et al., Helv. Phys. Acta 44, 141 (1971)] t + d 4 He + n Factor: ~1.5 at 107 keV J = 3/2 + / s-wave dominated (~96%) H. Paetz gen. Schieck, Eur. Phys. J. A 44, (2010) Polarized Fusion

5 Measurements in Basel 1971 An increased total cross section is possible !!! Depending on the spin combinations the differentiell cross sections can be optimized !!!

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

7 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)

8 What is the advantage for fusion reactors ? Calculation by M. Temporal et al. for the „Megajoule“ Project Polarized Fusion No optimization of the laser power: Gain increased by factor 4 with use of polarized fuel

9 What is the advantage for fusion reactors ? 2.) Magnetic Confinement (Tokomak): Collaboration between Jlab (A. Sandorfi et al.), University of Virgina, Oak Ridge Lab. and the DIII-Tokomak in San Diego Polarized Fusion Idea: Feed DIII tokomak with polarized 3 He and D produced with the methods of frozen spin targets like at Jlab.

10 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 !

11 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

12 Deltuva and Fonseca, Phys. Rev. C 81 (2010) 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

14 PNPI

15 The Electron Screening Effect Distance Coulomb Potential Astrophysical S-Factor: F. Raiola et al.; Eur. Phys. J. A 13, 377 (2002) Nuclear Potential

16 The Electron Screening Effect Distance Coulomb Potential ?

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 ? a.) Magnetic confinement: - R.M. Kulsrud et al.; Phys. Rev. Lett. 49, 1248 (1982) - Experiment by Sandorfi et al. b.) Inertial Fusion: - J.P. Didelez and C. Deutsch; 2011 Laser and Particle Beams M. Büscher (FZJ / Uni. Düsseldorf) „Laser Acceleration“ Polarized Fusion

18 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 targets JUSPARC Project in FZJ

19 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 ? - inertial fusion: - HD targets are available (10 mK, ~15 T) (relatively small polarization ~ 40%) - frozen spin DT targets possible - magnetic confinement: a.) pol. 3 He is available („Laser-pumping“) b.) pol. T will be possible with a similar method c.) pol. D ??? Polarized Fusion

20 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

21 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)?

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

23 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 H 2 - Ions: + T Cell = 100 K

24 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 ? - inertial fusion: - frozen spin DT targets possible (relatively small polarization ~ 40%) - HD targets are available - magnetic confinement: a.) pol. 3 He is available („Laser-pumping“) b.) pol. T will be possible with a similar method c.) pol. D ??? => new ideas are wellcome !!!! Polarized Fusion