  The presence of non-axisymmetric perturbations in an axisymmetric magnetic
field equilibrium renders the Guiding Center (GC) particle motion
non-integrable and may result in particle, energy and momentum redistribution,
due to resonance mechanisms. We analyse these perturbations in terms of their
spectrum, as observed by the particles in the frame of unperturbed GC motion.
We calculate semi-analytically the exact locations and strength of resonant
spectral components of multiple perturbations. The presented Orbital Spectrum
Analysis (OSA) method is based on an exact Action-Angle transform that fully
takes into account Finite Orbit Width (FOW) effects. The method provides
insight into the particle dynamics and enables the prediction of the effect of
any perturbation to all different types of particles and orbits in a given,
analytically or numerically calculated, axisymmetric equilibrium.
