Transient Filamentation of a Laser Beam in a Thermal Force Dominated Plasma

Abstract

Experimental evidence for the transient phase of the filamentation instability of a laser beam in a thermal force dominated plasma is presented. When the laser beam is crossed with a weaker degenerate probe beam at a small angle, the interference of the two beams drives a thermally enhanced ion grating which during its transient phase acts to seed the filamentation/forward Brillouin instability. [S0031-9007(96)02241-7]

Observation of Energy Transfer between Identical-Frequency Laser Beams in a Flowing Plasma

“…More recently, Lal et al have observed energy transfer between two l 10.6 mm wavelength laser beams [8], but this was during a transient period on the order of a few acoustic periods, during which energy transfer may occur between identical frequency beams [9,10]. These previous experiments were performed in subsonic plasmas.…”

High Power Dynamic Polarization Control Using Plasma Photonics

“…While the steady-state response of the system in this frequency-degenerate case involves a phase delay without any energy transfer, the beat wave initially drives a transient grating [13] that can transfer energy, which would violate an assumption built into the polarimetry data analysis. The system should reach steady-state in a time τ sat ≈ ∆φ/(2ν 2 ω IAW ) , where ν is the ion acoustic damping rate (normalized to the ion acoustic frequency); this becomes comparable to the probe pulse duration as the pump intensity is increased in these weakly-damped plasmas.…”

Laser-plasma interactions relevant to Inertial Confinement Fusion

“…Lal et al have observed energy transfer between two λ = 10.6µm wavelength laser beams [31], but this was during a transient period on the order of a few acoustic periods, during which energy transfer may occur between identical frequency beams [32,33].…”