The purpose of this paper is to continue our investigation into period
ic solutions of strongly non-linear Mathieu oscillators. The modified
version of the generalized averaging method which we developed recentl
y is applied to derive highly accurate analytical expressions for thes
e periodic solutions. These analytical results are used, together with
the perturbation methods of multiple time scaling, to obtain second o
rder expressions for the stability regions of these periodic solutions
. The analytical research results are verified with numerical computat
ions. Very good agreement is found, which shows the applicability of t
he modified version of the generalized averaging method to this kind o
f strongly non-linear oscillators. These oscillators may be used to mo
del the beam-beam interaction in particle accelerators. (C) 1997 Elsev
ier Science Ltd.