9-14 September 2018
University of Ferrara
Europe/Rome timezone
23RD INTERNATIONAL SPIN SYMPOSIUM

Optical excitation of molecules for Spin-Polarized Nuclear Fusion

12 Sep 2018, 16:40
25m
A11 (Polo degli Adelardi - Via Adelardi, 33)

A11

Polo degli Adelardi - Via Adelardi, 33

Parallel Sessions Application of Nuclear Polarization Techniques to Other Fields Application of Nuclear Polarization Techniques to Other Fields

Speaker

Prof. T. Peter Rakitzis (IESL-FORTH)

Description

It is known theoretically and from scattering experiments that nuclear spin polarization increases the cross sections of the D-T and D-3He reactions by 50%, while also spatially aligning the recoil directions of the reactions products, which can be used to improve the efficiency of reactors [1]. However, the lack of a sufficiently intense source of spin-polarized deuterium (SPD) has not yet allowed the observation of spin-polarized fusion in a plasma, which has left three important questions unanswered [1]: (1) Does nuclear spin-polarization survive long enough in the plasma to benefit fusion? (2) What is the effect of spin-polarization on the D-D reaction (which occurs as a side reaction in both D-T and D-3He), as numerous theoretical predictions range from prediction of enhancement to suppression? (3) Can a source of SPD be found with a production rate of 10^22 SPD/s, necessary for a nuclear reactor, such as ITER (as traditional methods, e.g. Stern-Gerlach spin separation or spin-exchange optical pumping, have production rates about 4-5 orders lower)? We describe two novel methods that we have developed, for the production of spin-polarized hydrogen isotopes through the UV and IR optical excitation of molecules [2-6]. We describe how the UV photodissociation method gives spin-polarized D nuclei at densities of at least 10^19 SPD/cm3, which is sufficient for the observation of inertial-confinement polarized fusion using kJ-MJ pulsed lasers [3]. In addition, we discuss some details of how the IR excitation method may be able to produce beams of 10^22 SPD/s, needed for polarized magnetic-confinement fusion, and, therefore, how the three fundamental questions of polarized fusion may be answered. References [1] R. Engels et al., “Polarized fusion” Phys. Part. Nucl. 45, 341 (2014). [2] D. Sofikitis et al., “Ultrahigh-density spin-polarized H and D observed via magnetization quantum beats” (submitted). [3] D. Sofikitis et al., “Highly nuclear-spin-polarized deuterium atoms from the UV dissociation of Deuterium Iodide” Phys. Rev. Lett. 118, 233401 (2017). [4] T.P. Rakitzis et al., “Spin Polarized Hydrogen Atoms from Molecular Photodissociation,” Science 300, 1936 (2003). [5] T.P. Rakitzis, “Highly spin-polarized atoms and molecules from rotationally state-selected molecules” Phys. Rev. Lett. 94, 83005 (2005). [6] L. Rubio-Lago et al., “Time-dependent polarization transfer from molecular rotation to nuclear spin” Phys. Rev. A 74, 042503 (2006).

Primary author

Prof. T. Peter Rakitzis (IESL-FORTH)

Co-authors

Mr Chrysovalantis Kannis (IESL-FORTH) Dr Dimitris Sofikitis (IESL FORTH) Mr Gregoris Boulogiannis (IESL-FORTH)

Presentation Materials