Precession of toroidally passing particles in tokamaks and spherical tori

The toroidal precession of the circulating particles and semitrapped particles (toroidally passing but poloidally trapped particles) is studied. Expressions for the precession frequency, which are convenient for practical use, are obtained and analyzed. It is found that the key parameters that determine the magnitude and the direction of the precession velocity are the plasma elongation, the magnitudes and profiles of the safety factor and β defined as the ratio of the local plasma pressure to the magnetic field pressure at the magnetic axis. An important role of the “paramagnetic” precession in highly elongated plasmas is revealed. The analysis carried out is based on the obtained expressions for the equilibrium magnetic field strength and the field line curvature.