Evidence in the second-harmonic emission for self-focusing of a laser pulse in a plasma

Journal Article · Thu Aug 01 00:00:00 EDT 1985 · Phys. Fluids; (United States)

DOI:https://doi.org/10.1063/1.865264· OSTI ID:5398737

Stamper, J A; Lehmberg, R H; Schmitt, A; Herbst, M J; Young, F C; Gardner, J H; Obenschain, S P

Short-pulse (300 psec), high-intensity (10/sup 14/-10/sup 15/ W/cm/sup 2/) Nd-laser light was propagated into variable scale length plasmas (L/sub n/equivalentn/deln = 200--400 ..mu..m at 0.1 critical density)= preformed by long-pulse (4 nsec), low-intensity (approx. =6 x 10/sup 12/ W/cm/sup 2/) irradiation of planar targets. For high short-pulse intensities (> or =5 x 10/sup 14/ W/cm/sup 2/), time-integrated images show filament-shaped regions of second-harmonic (2..omega../sub 0/) emission from the low density (0.01< or =n/sub e//n/sub c/< or =0.2) region of the ablation plasma. Two-dimensional computer calculations of the hyrodynamics and laser beam propagation indicate that these filaments are consistent with ponderomotive self-focusing of the short pulse. A theoretical model that explains the 2..omega../sub 0/ generation mechanism within low-density filaments is also presented.

• Research Organization: U. S. Naval Research Laboratory, Washington, DC 20375-5000
• OSTI ID: 5398737
• Journal Information: Phys. Fluids; (United States), Vol. 28:8
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
LASER-PRODUCED PLASMA
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PHOTON EMISSION
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PULSE RISE TIME
PULSES
TWO-DIMENSIONAL CALCULATIONS
EMISSION
FLUID MECHANICS
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700108* - Fusion Energy- Plasma Research- Wave Phenomena