This project will formulate a comprehensive and self-consistent theory of electron and ion acceleration in impulsive solar flares, and specifically to account for the near simultaneous acceleration of electrons and ions as manifested by the approximately coincident observed time profiles of X-ray and nucleation de-excitation line emission. The PIs will investigate in detail the evolution of an initially Maxwellian electron distribution in response to an applied DC electric field, taking into account wave generation and the resulting feedback of the waves on the electrons. They will also investigate the parametric decay of these waves into lower hybrid sidebands and low-frequency electrostatic waves. Theoretical results will be compared with observations of solar flares whenever possible to guide subsequent work and progressively constrain model parameters. This research aims to explain near simultaneous acceleration of electrons and ions, as well as the high electron/proton ratio in impulsive solar flares.