In this contribution, we report on the results of analytical approaches and computer simulations of laser beam self- defocusing in laser induced plasma and gas oncoming flow above a cavity in deep penetration welding at atmospheric conditions. Nonlinear lens-like processes in oncoming jet flow ensure the feedback loop between the evaporation, penetration and laser beam intensity distribution in a workpiece. The processes are self-consistent with the conditions of the stable cavity existence. It is shown that the oncoming hot air jet flow above the plume brings the main contribution in the steady state and instability of the nonlinear beam broadening, which may reach 300%.

Date Published: 1 February 2001
PDF: 10 pages
Proc. SPIE 4348, Fourth International Workshop on Nondestructive Testing and Computer Simulations in Science and Engineering, (1 February 2001);

Published in SPIE Proceedings Vol. 4348:
Fourth International Workshop on Nondestructive Testing and Computer Simulations in Science and Engineering
Alexander I. Melker, Editor(s)