ABSTRACT
This chapter focuses on the guiding-center method. Various types of codes have been developed in an attempt to convey the pertinent physics, while overlooking less important phenomena. This method exhibits a partially fluid-like behavior in the direction perpendicular to the ambient magnetic field. A guiding-center model may be profitably used when the motion consists of a fast oscillatory motion plus another slower motion. A similar effect may be seen in meteorological and geophysical settings. The role of the magnetic field is played by the angular momentum vector and the role of the electric field by the pressure gradient. Electrostatic perturbations completely normal to the field line lose the property. The disadvantage of this algorithm is the computational expense associated with the operations equations. Two major effects which are omitted in the guiding-center description are polarization drift effects and finite Larmor radius effects.
