ENERGY-ABSORPTION IN A CONICAL CAVITY TRUNCATED BY SPHERICAL CAP SUBJECT TO A FOCUSED HIGH-INTENSITY BEAM

Energy absorption of a conical cavity truncated by a spherical cap sub ject to a focused beam is systematically and quantitatively investigat ed. The incident flux on any transverse cross-section has a Gaussian d istribution, which is specified by the convergence angle, energy distr ibution parameter at the focal spot, and focal spot location relative to the workpiece surface. Absorption and scattering within the plasma in the cavity are assumed to be negligible. By accounting for specular and diffuse reflections the results show the effects of the spherical cap and cone angles of the cavity, locations and sizes of the focal s pot, and convergence angles of the energy-beam on absorption. Asymptot ic results agree with available solutions of simple models. An explana tion for the occurrence of spiking in welding is also proposed. (C) 19 97 Elsevier Science Ltd.