Parametric channeling and collapse of beams of charged particles with internal structure in crystals: 1. Features of parametric channeling of molecular ions in crystal channels

A new type of self-organized orientational motion of charged particles with internal energy structure (molecules, atoms, and in some cases nuclei and electrons) in crystals, i.e., parametric channeling, is proposed and studied in detail. A feature of this mode of motion is associated with the strong parametric coupling of orientational oscillations controlled by the interaction of the moving particle charge with averaged fields of crystal plane axes and vibrations caused by intraparticle processes. The features of parametric processes during channeling of molecular diatomic ions are studied. It is shown that this effect can cause “parametric collapse,” i.e., beam self-cooling, compression, and a decrease in its phase-space volume. For molecules whose axis is perpendicular to the channel axes, periodic parametric collapse occurs. For molecules oriented along the channel, beam self-cooling is an asymptotic, aperiodic, and irreversible process.