  Charged particle motion in axisymmetric toroidal magnetic fields is analyzed
within the context of the canonical Hamiltonian Guiding Center theory. A
canonical transformation to variables measuring the drift orbit deviation from
a magnetic field line is introduced and an analytical transformation to
Action-Angle variables is obtained, under a zero drift width approximation. The
latter is used to provide compact formulas for the orbital spectrum of the
drift motion, namely the bounce/transit frequencies as well as the
bounce/transit averaged toroidal precession and gyration frequencies. These
formulas are shown to have a remarkable agreement with numerically calculated
full drift width frequencies and significant differences with standard
analytical formulas based on a pendulum-like Hamiltonian description. The
analytical knowledge of the orbital spectrum is crucial for the formulation of
particle resonance conditions with symmetry breaking perturbations and the
study of the resulting particle, energy and momentum transport.
