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)
