  A new analytic expression is derived for the resonant drive of high n
Alfvenic modes by particles accelerated to high energy by Ion Cyclotron
Resonance Heating. This derivation includes finite orbit effects, and the
formalism is completely non-perturbative. The high-n limit is used to calculate
the complex particle response integrals along the orbits explicitly. This new
theory is applied to downward sweeping Alfven Cascade quasimodes completing the
theory of these modes, and making testable predictions. These predictions are
found to be consistent with experiments carried out on the Joint European Torus
[P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)].
