Polarized Fusion. Can Polarization Help to Increase the Energy Output of Fusion Reactors?

Abstract

Since more than 60 years scientists are working on the idea to produce energy from nuclear fusion of light particles like the Hydrogen isotopes. In the meantime, the energy output of e.g. tokamak reactors was increased by five orders and modern experiments like JET are approaching the border for energy production. The international ITER collaboration is preparing the first fusion reactor that will produce about ten times more energy, compared to the energy that is needed to run the experiment. Today, the laser-induced inertial fusion reached the same level and experiments at the National Ignition Facility (NIF) in California, USA, demonstrate a ratio between produced and induced energy about one at the end of 2013.1 In parallel, it is discussed since 1970 to use nuclear polarized fuel to increase the total cross sections of the different fusion reactions.2 The energy gain of fusion reactors does not depend linearly on the total cross section. Depending on the different concepts for nuclear fusion, magnetic confinement or inertial fusion, the energy gain This is an Open Access article published by World Scientific Publishing Company. It is distributed under the terms of the Creative Commons Attribution 3.0 (CC-BY) License. Further distribution of this work is permitted, provided the original work is properly cited. 1660112-1 Int. J. Mod. Phys. Conf. Ser. 2016.40. Downloaded from www.worldscientific.com by UNIVERSITY OF FERRARA on 04/19/16. For personal use only. R. Engels & G. Ciullo is improved above average. M. Temporal et al. have shown, e.g., that the energy gain of laser-induced inertial fusion might be increased by a factor four, or that the necessary laser power can be reduced by 20 %, if the nuclear fuel was polarized before.3 The downsized laser power will reduce the costs of the corresponding project by a reasonable amount. In addition, the differential cross sections can be modified so that it will be possible to focus the ejectiles, e.g. the neutrons, on special wall areas. In a tokamak this can be used to concentrate the neutron flux to special outer parts of the blanket, where the cooling can be improved and the neutrons be used for Tritium production via the exothermic reaction 6Li+n → 4He+t.4 At the same time, less cooling is needed for the inner parts of the blanket that allows to bring the magnetic field coils closer to the fusion plasma. The increased magnetic field in the plasma will increase the energy gain additionally. Another option of polarized fuel is a new kind of plasma diagnostic inside a tokamak. In combination with modern Nuclear Magnetic Resonance technologies (NMR) anisotropies in the plasma can be measured to learn more about the different plasma mode