Sources of intense tunable vacuum ultraviolet radiation, obtained using non-linear mixing of visible laser radiation, will be used for non-linear excitations in atoms . One application will involve ultra-high resolution studies of atomic helium for basic standards work and tests of quantum electrodynamics in two electron atoms. A second application involves use of a source of multiple pulses of transform-limited radiation to cool atomic hydrogen, which will be used to study many-body processes. A third program involves study of core excitations and multi- electrons excitations of atoms in intense radiation fields.