Influence of the focal point position on the properties of a laser-produced plasma

Journal Article · Mon Oct 15 04:00:00 EDT 2007 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2795629· OSTI ID:21057461

Kasperczuk, A; Pisarczyk, T; Badziak, J; Miklaszewski, R; Parys, P; Rosinski, M; Wolowski, J; Stenz, CH; Ullschmied, J; Krousky, E; Masek, K; Pfeifer, M; Rohlena, K; Skala, J; Pisarczyk, P ^[1]

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1. Institute of Plasma Physics and Laser Microfusion, 23 Hery St., 00-908 Warsaw (Poland)

This paper deals with investigations of the influence of the focusing lens focal point position on the properties of a plasma produced by a defocused laser beam. The experiment was carried out at the Prague Asterix Laser System iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikova, J. Krasa, E. Krousky, P. Krupickova, L. Laska, K. Masek, T. Mocek, M. Pfeifer, A. Prag, O. Renner, K. Rohlena, B. Rus, J. Skala, P. Straka, and J. Ullschmied, Phys. Plasmas 8, 2495 (2001)] by using the third harmonic of laser radiation ({lambda}=0.438 {mu}m), laser energy of 70 J, pulse duration of 250 ps (full width at half-maximum), and beam spot radii of 250 and 400 {mu}m. Cu and Ta were chosen as target materials. The experimental data were obtained by means of a three-frame interferometric system, ion collectors, and crater replica techniques. The reported results allow formulating an important hypothesis that the laser-produced plasma modifies strongly the laser intensity distribution. It is shown how such a modification depends on the relative position and distance of the focal point to the target surface. Of particular importance is whether the focal point is located inside or in front of the target. The irradiation geometry is crucial for the possibility of generating plasma jets by laser radiation. Well-formed jet-like plasma structures can be created if an initially homogeneous laser intensity distribution is transformed in the plasma to an annular one.

• OSTI ID: 21057461
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 10 Vol. 14; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
FOCUSING
GEOMETRY
IODINE LASERS
IONS
LASER RADIATION
LASER-PRODUCED PLASMA
LIGHT TRANSMISSION
PLASMA HEATING
PLASMA JETS
REPLICA TECHNIQUES
VISIBLE RADIATION