Non-standard particle orbits in a thermonuclear tokamak plasma

The problem of determining the orbits of energetic ions in the confining ma gnetic field of a tokamak plasma and their phase space characteristics is c onsidered analytically. First, starting from the orbit invariants in the si mplified magnetic field of a tokamak plasma, a quartic equation describing the trajectories in configuration space is derived. Then from an examinatio n of the coefficients of the orbit equation, the orbit types and their clas sification are deduced. Analytic solutions of the orbit equation are given and the partition of phase space into regions of trapped (passing) particle s and loss cones is determined. Finally, as a specific application, the tra jectories and phase space characteristics of 3.5 MeV alpha particles in the magnetic field of the JET tokamak are calculated.