ABSTRACT
This chapter explains that the ballooning representation is formally different from the Fourier representation by the fact that the radial wave number is dependent on the ballooning variable. It provides the perturbed current density in terms of the transverse and the longitudinal parts, which is convenient in the problems of small-scale perturbations. The chapter explains the flute and the oscillating parts of the perturbation assuming the oscillating part to be related to the metric oscillations. It deals with the current closure equation. The chapter discusses the ballooning variable and the ballooning representation. The ballooning modes occupy a region with a large number of resonant surfaces and in this sense are non-local.
