Supercritical Density Modifications of a Laser-Produced Plasma Due to Resonant Cavity Fields

A laser plasma is produced at the center of a cylindrical cavity while radio-frequency excitation of moderate power is supplied near the TM011 and TE111 vacuum-mode frequencies. Probe and particle collector measurements show density modification of the plasma during its decay due to resonances excited by the RF source. The magnitudes of these density changes are found to be near and exceeding critical (ωp = ωRF) density.