Experimental study of the transmission of breakdown plasma generated during laser shock processing

Centre Laser Franco-Allemand (CLFA), Laboratoire pour l'Application des Lasers de Puissance (LALP), 16 bis, avenue Prieur de la Côte d'Or, 94114 Arcueil Cedex, France

Corresponding authors: berthe@etca.fr fabbro@etca.fr

Received: 6 January 1998
Revised: 16 April 1998
Accepted: 30 April 1998
Published online: 15 August 1998

Abstract

Shock wave generation from laser-produced plasma in water confinement regime for an incident 25–30 ns / 40 J / λ = 1.064 µm laser beam has been studied. Transmitivity measurement of the parasitic plasma breakdown at the surface of water confinement has been performed with a continuous laser probe. Above 6 GW/cm² incident laser intensity, the critical electronic density for the laser wavelength is achieved inside the plasma by cascade ionization during the pulse duration. Above 10 GW/cm², peak power density transmitted through the plasma saturates. The laser pulse transmitted through the breakdown plasma corresponds to the part of incident laser pulse preceding the transmission cut-off.