  The stability theory of the skin layer plasma of the inductive discharge is
developed for the case when the electron quiver velocity in RF wave is of the
order of or is larger than the electron thermal velocity. This theory is
grounded on the methodology of the oscillating modes, which accounts for the
oscillation motion of the electron component relative to the unmovable ions in
the spatially inhomogeneous RF field of the skin layer. The theory predicts the
existence the instability of the parametric type in a skin layer with the
growth rate comparable with frequency. This instability stems from the coupled
action of two effects caused by the electron-ion relative motion in RF field:
occurrence of harmonics of the perturbed potential and their coupling due to
the ponderomotive current. The instability exists in the finite interval of the
ponderomotive current velocity and is absent in the uniform boundless plasma.
