Relevant Spatial and Time Scales in Tokamaks

Abstract

Nuclear fusion with polarized fuel looks especially attractive in the perspective of increasing the reaction rates or providing a preferential direction to the emission of the fusion products. Considering the difficulties encountered in reaching the necessary plasma conditions, however, the problem of producing and maintaining a polarized plasma may appear as an additional, and unwarranted, complication. Nevertheless, it can be observed that since most of the fusion reactions take place in the very central part of the plasma column in a tokamak, it may not be impossible to sustain long enough the fuel polarization in that region, where both particle and energy confinement are higher, and instabilities are lower. The possibility of utilizing standard auxiliary heating systems at the ion cyclotron range of frequency to interact with the nuclear magnetic moments of deuterium or tritium is considered, with some preliminary results from a radiofrequency propagation code showing the polarization states of two waves, resonating respectively with the D and T precession frequency.