Abstract: An apparatus and a method for generating repetitive planar detonation waves at varying and controllable frequencies are provided. The apparatus utilizes the over-pressure associated with each detonation wave to interrupt the ambient pressure, post-injection mixing of the reactant gases between the detonation cycles. In-line mechanical valves can be used to positively interrupt one or both reactant gases if the reaction within the detonation tube degrades to deflagrative burning. The detonation system can be optimized during operation by monitoring either the detonation wave pressure or velocity and adjusting the reactant gas mixture accordingly.