Laser interaction with some Bi-ferrites

摘要

The three dimensional thermal equation is not solved generally even for "classical" problems [1-4], so the thermal modeling of the laser-material interaction is usually beyond the scope of classical models. Many complex physical and chemical processes accompany the laser-material interaction. Besides, the relations between the heat (low and temperature gradient, e.g., dependencies of thermal and temperature conductivity coefficients of structure, state of matter, temperature, external fields, atmosphere and other parameters are not well known [5-10]. Various methods of thermal conductivity measurements give differing results [5]. Experimental errors could be 10-20%, depending on the method, sample geometry and material. It is apparent that over limited temperature ranges, appropriate empirical laws could be as useful as complicated "exact" theoretical treatments [1-3, 10]. Resistivity measurements are reliable and simple and their temperature dependence could give a hint to the thermal conductivity behavior considerations [5, 11]. Another important parameter of laser-material interaction, coefficient of reflection, i.e., absorption, depends on electron plasma frequency and the mean collision time, also available from electrical conductivity measurements [12].