Laser heating and combustion of materials by obliquely incident radiation

An analysis is made of laser heating of a bulk metal sample when an exothermal reaction takes place on its surface. The limit of stability is found in the form of a critical curve P=P_cr(r₀), where P is the power and r₀ is the radius of the radiation beam, such that for P>P_cr (r₀) the combustion affects the whole surface of the sample. It is shown that in the case of oblique incidence of laser radiation on the surface the ignition threshold P_cr(r₀) of a sample depends on the polarization of the radiation and can be much lower than in the case of normal incidence. The theory developed in the present paper is in agreement with experimental results.