Ion polarization in magnetic fields

Abstract

The use of polarized ions for fuelling fusion reactors was proposed more than 30 years ago as a tool to increase both reactivity and background control. This idea was received with some skepticism by the relevant scientific community, due to some uncertainty in the physics of the process, the low efficiency in the production of polarized beams for injection into plasma and the apparent difficulty of preserving the ion polarization for a time long compared with nuclear burning time. But more recently, as a consequence of significant progress in the field of atomic beam sources and polarized targets, the interest in this matter has been refreshed for both inertially and magnetically confined plasmas. In this paper, after a general introduction to the problem, we present some remarks on the interaction between polarized ions and magnetic fields, both static and varying at radiofrequencies, also in view of a possible implementation of a large RF power system such as it is typically used in tokamaks for plasma heating via ion cyclotron resonance. Some numerical examples are given with reference to the IGNITOR project.