Stochastic ion heating in a field-reversed configuration geometry by rotating magnetic fields

Abstract

Ion heating by application of rotating magnetic fields (RMFs) to a prolate field-reversed configuration (FRC) is explored by analytical and numerical techniques. For odd-parity RMFs (RMFo), perturbation analysis shows ions in figure-8 orbits gain energy at resonances of the RMFo frequency ωR, with the figure-8 orbital frequency ω. Since figure-8 orbits tend to gain the most energy from the RMF and are unlikely to escape in the cusp region (where most losses occur), they are optimal candidates for rapid stochastic heating, as compared to cyclotron and betatron orbits. Comparisons are made between heating caused by even- and odd-parity RMFs and between heating in currently operating and in reactor-scale FRC devices.