Fast processes of cluster excitation under the action of an ultrashort superpower laser pulse or as a result of cluster collisions are considered. Processes are studied for cluster absorption of a laser pulse and the subsequent evolution of a forming cluster plasma, as well as the evolution of a cluster plasma initiated by cluster collisions. The properties of this plasma as a source of X-ray emission are analyzed. The generation of neutrons results from the excitation of a deuterium cluster beam by a laser pulse and from the collision of an accelerated beam of deuterium clusters with a deuterium target, including a dense beam of deuterium clusters.